&EPA
United States
Environmental Protection
Agency
Office of
Toxic Substances
Washington DC 20460
EPA 560/6-78-005
August 1978
Toxic Substances
Chemical Market
Input/Output
Analysis of
Selected
Chemical Substances to
Assess Sources of
Environmental
Contamination
Task III Asbestos
-------
EPA 560/6-78-005 TR 77-515
CHEMICAL MARKET INPUT/OUTPUT
ANALYSIS OF SELECTED CHEMICAL SUBSTANCES TO ASSESS
SOURCES OF ENVIRONMENTAL CONTAMINATION:
TASK III. ASBESTOS
William M. Meylan
Philip H. Howard
Sheldon S. Lande
Arnold Hanchett
Contract No. 68-01-3224 - Task III
SRC No. L1273-08
August 1978
Project Officer - Joseph J. Breen
Prepared for:
Office of Toxic Substances
U.S. Environmental Protection Agency
Washington, D.C. 20460
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NOTICE
This report has been reviewed by the Office of Toxic Substances, EPA,
and approved for publication. Approval does not signify that the contents
necessarily reflect the views and policies of the Environmental Protection
Agency, nor does mention of trade names or commercial products constitute
endorsement or recommendation for use.
ii
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TABLE OF CONTENTS
1.0 INTRODUCTION 1
2.0 DESCRIPTION OF ASBESTOS 2
2.1 Composition and Properties of Asbestos 2
2.2 Asbestos Grading 12
2.3 Major Uses of the Asbestoses 15
2.3.1 Chrysotile 15
2.3.2 Crocidolite 18
2.3.3 Amosite 18
2.3.4 Tremolite and Actinolite 18
2.3.5 Anthophyllite 19
3.0 DESCRIPTION OF THE ASBESTOS INDUSTRY 20
3.1 Industry Structure 20
3.2 Types of Plants 25
3.3 Numerical and Percentage Distribution of Plants, Employees, 27
and Production
4.0 MARKET INPUT/OUTPUT DATA 30
4.1 Mine Production 30
4.2 Exports 33
4.3 Imports 41
4.4 Supply-Demand-Use 42
4.5 Asbestos Fiber Prices 42
4.6 Future Outlook 49
5.0 MINING AND MILLING 53
5.1 U.S. Mines and Mills 53
5.1.1 Ore Characteristics 57
6.0 FRICTION MATERIALS 60
6.1 Statistics 60
6.1.1 Use Quantity and Shipment Values 60
6.1.2 Industrial Firms 62
6.1.3 Plants 66
6.1.4 Future Projections for Asbestos (Clifton, 1975) 68
iii
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Table of Contents (Cont'd)
Page
6.2 Manufacturing Process Technology 69
6.2.1 Molded Products 69
6.2.1.1 Dry-Mix Process 69
6.2.1.2 Wet-Mix Process 69
6.2.2 Woven Products 71
6.3 Composition of Friction Materials 74
6.3.1 Binders 76
6.3.2 Property Modifiers 76
6.3.2.1 Non-Abrasive Modifiers 76
6.3.2.2 Abrasive Modifiers 78
6.3.3 Composition 79
6.3.4 Summary 79
6.4 Asbestos Emissions from Brake Lining Use 81
6.4.1 Published Literature 82
6.4.1.1 Discrepancies in Asbestos Content of 82
Emissions or Debris
6.4.1.2 Collection Methodologies and Particle Size 86
Distribution
6.4,1.3 Analysis Techniques 87
6.4.1.4 Other Considerations 89
6.4.2 Emission Quantities 91
6.4.2.1 A Hypothetical Calculation 94
6.4.3 Human Exposure to Asbestos Emissions During Brake 96
Lining Maintenance and Repair
6.5 Alternatives to Asbestos as a Friction Material 99
6.5.1 The Role of Asbestos in Friction Linings 99
6.5.2 Alternatives in Brake Linings 99
6.5.3 Alternatives in Disc Brake Pads 101
6,5.4 Alternatives In Clutches 102
Iv
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Table of Contents (Cont'd)
Pa
6.6 Quantities of Asbestos Released to the Environment from 102
Manufacture
6.6.1 Release from Baghoujes and Product Scrap* 103
6.6.2 Release from Wet Dust Collection 105
7.0 ASBESTOS-CEMENT PIPE 107
7.1 Use Quantity, Shipment Values, and Industrial Firms 108
7.2 Manufacturing Process Technology 111
7.3 Quantities of Asbestos Released to the Environment from 114
Manufacture
7.3.1 Release from Baghouses and Rejected Pipe and Scrap 115
7.3.2 Release from Process Wastevaters 120
7.4 Asbestos Release from the Use of A-C Pipe 123
7.5 Alternatives to A-C Pipe 129
7.5.1 Fiber Replacement in Cement 131
8.0 ASBESTOS-CEMENT SHEET 133
8.1 Use Quantities, Shipment Values, and Industrial Firms 133
8.2 Manufacturing Process Technology 134
8.3 Quantities of Asbestos Released to the Environment from 137
Manufacture
8.3.1 Release from Baghouses and Rejected Sheet and Scrap 138
8.3.2 Release from Process Wastewaters 139
8.4 Asbestos Release from Use of A-C Sheet 141
8.5 Alternative Products to A-C Sheet 142
9.0 ASBESTOS IN THE ROOFING INDUSTRY 144
9.1 Asbestos Roofing Products 145
9.2 Manufacturing Technology 147
9.3 Quantities of Asbestos Released to the Environment from 155
Manufacture
9.3.1 Release from A-C Sheet and Shingle Production 155
9.3.2 Release from Asbestos Paper Production 155
9.3.3 Release from Asphalt and Paper Coating Operations 157
9.3.4 Release from Mastic Asphalt Mix Production 159
9.3.5 Overall Considerations 160
9.4 Release of Asbestos from Installed Roofing Products 160
9.5 Alternatives to Asbestos Roofing Products 163
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Table of Contents (Cont'd)
Page
10.0 ASBESTOS PAPER 164
10.1 Use Quantities and Industrial Firms 165
10.2 Manufacturing Process Technology 166
10.3 Quantities of Asbestos Released to the Environment from 169
Manufacture
10.3.1 Release from Process Wastewaters 169
10.3.2 Release from Process Scraps and Baghouses 174
10.4 Release of Asbestos from Use of Paper Products 175
10.4.1 Floor Underlayments and Pipe Wraps 175
10.4.2 Diaphragms for Brine Cells 176
10.4.3 Beverage and Drug Filters 177
10.5 Alternatives to Asbestos in Paper 180
11.0 ASBESTOS FLOORING 182
11.1 Use Quantity, Shipment Values, and Industrial Firms 182
11.2 Manufacturing Process Technology 184
11.3 Quantities of Asbestos Released to the Environment from 188
Manufacture
11.4 Release of Asbestos from Asbestos Flooring Use 189
11.5 Alternative Products to Asbestos Flooring 191
12.0 ASBESTOS INSULATION 193
12.1 Asbestos Insulation Products, Uses, and Economic Trends 193
12.2 Manufacturing Technology 199
12.3 Asbestos Released to the Environment During Manufacture 203
12.4 Asbestos Released to the Environment from Installed 208
Insulation
12.5 Alternative Materials to Asbestos for Insulation 211
13.0 PACKING AND GASKETS 213
13.1 Asbestos Packing and Gasket Products, Uses and Economic 213
Factors
13.2 Manufacturing Technology 216
13.2.1 Gaskets 216
13.2.2 Dynamic Packing 218
13.3 Asbestos Released to the Environment During Manufacture 219
13.4 Asbestos Released to Environment After Insulation 222
13.5 Alternative Materials to Asbestos for Gaskets and Packing 223
vi
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Table of Contents (Cont'd)
14.0 TEXTILES 225
14.1 Uses and Economic Factors 225
14.2 Manufacturing Technology 232
14.3 Asbestos Release to the Environment from Textile Manufacture 234
14.4 Release of Asbestos Textile Products to the Environment 237
During Use
14.5 Alternatives to Asbestos Textiles 237
15.0 ASBESTOS COATING AND PAINT COMPOUNDS 239
15.1 Uses of Asbestos in Coatings, Paints, and Sealants 239
15.2 Manufacturing Technology 244
15.3 Asbestos Released to the Environment During Manufacture 245
15.4 Asbestos Released to the Environment During Uses 246
15.5 Alternative Materials to Asbestos for Protective Coatings 248
and Paints
16.0 ASBESTOS-REINFORCED PLASTICS 252
16.1 Use Quantity and Economic Data 253
16.2 Manufacturing Process Technology 255
16.3 Release of Asbestos to the Environment from Manufacture 258
16.4 Fiber Release from Product Use 260
16.5 Alternatives 261
17.0 MISCELLANEOUS ASBESTOS USES 262
17.1 Patching Compounds 264
17.1.1 Application and Manufacture of Patching Compounds 265
17.1.2 Environmental Asbestos Release from Manufacture 267
17.1.3 Environmental Asbestos Release from Use 267
17.1.4 Alternatives 270
17.2 Drilling Muds 271
17.2.1 Environmental Emissions 272
17.2.2 Alternatives 273
17.3 Asphalt-Asbestos Concrete 275
17.3.1 Manufacturing and Emissions 276
17.3.2 Emissions from Product Use 276
vii
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Table of Contents (Cont'd)
Page
17.4 Shotgun Shell Base Wads 276
17.4.1 Manufacturing Emissions 277
17.4.2 Use Emissions 278
17.4.3 Alternatives 278
17.5 Artificial Fireplace Ashes 278
17.6 Other Uses 279
18.0 SUMMARY OF ASBESTOS END-USES AND EMISSIONS FROM MANUFACTURE AND 280
PRODUCT USE
18.1 Asbestos Emissions from Manufacturing 280
18.2 Asbestos Emissions from Product Use 287
18.3 Asbestos Emissions from Product Disposal 288
19.0 SOURCES OF ASBESTOS OTHER THAN FROM ITS COMMERCIAL PRODUCTION 291
AND USE
19.1 Talc 291
19.2 Taconite Wastes 295
19.3 Rock Quarries 296
19.4 Summary 297
20.0 SUMMARY ASSESSMENT 298
REFERENCES 304
viii
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LIST OF TABLES
Number Page
2.1 Approximate Chemical Formula of the Asbestoses 6
2.2 Chemical Composition of Common Fibrous Silicate Minerals 7
2.3 Chemical Composition of Asbestoses from Different Geographic 8
Locations
2.4 Physical, Chemical, and Mineralogical Properties of Varieties 9
of Asbestos
2.5 Chrysotile Grades by the Quebec Standard Test 13
2.6 Modifications in Grading American Mined Asbestos 16
3.1 Captive Fiber Sources for the Major American Asbestos 23
Product Manufacturing Firms
3.2 Twenty of the Largest U.S. Asbestos Product Manufacturers 24
3.3 Asbestos-Based Activity of Some Major Asbestos-Manufacturing 25
Companies
3.4 Industry Specialization and Primary Product Class 26
Specialization for Asbestos Product Producing
Establishments: 1972
3.5 Asbestos Products Manufacture: Distribution of Plant Sizes 28
3.6 Asbestos Products Manufacturing: Total Employment as a 29
Function of Size of Facilities
4.1 Mine Production of Asbestos 32
4.2 U.S. Export of Asbestos (Unmanufactured) for 1965 - 1975 33
4.3a U.S. Export — By Country — of Asbestos (Unmanufactured) 34
in 1975
4.3b U.S. Export — By Country — of Asbestos (Unmanufactured) 35
from January, 1976, to June, 1976
4.4 U.S. Exports — By Country ~ of Asbestos Manufactured 36
Products in 1975
ix
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List of Tables (Cont'd)
Number Page
4.5 U.S. Imports of Asbestos (Unmanufactured) for 1965 - 1975 41
4.6a U.S. Imports — By Country — of Unmanufactured Asbestos 43
in 1975
4.6b U.S. Imports — By Country — of Unmanufactured Asbestos, 44
January to June, 1976
4.7 U.S. Imports for Consumption of Asbestos 45
4.8 U.S. Imports — By Country — of Unmanufactured Asbestos 46
Products in 1975
4.9 Asbestos Supply-Demand Relationships, 1965-75 (Thousand 47
short tons)
4.10 Asbestos Distribution by End Use, Grade, and Type, 1974 47
(Short tons)
4.11 Buyers of Asbestos and Asbestos Ore 48
4.12 Time-Price Relationship for Asbestos 50
4.13 Recent Prices of Various Asbestoses 51
4.14 Projections and Forecasts for U.S. Asbestos Demand by End 52
Use, 1973 and 2000 (Thousand short tons)
5.1 American Asbestos Mines and Mills 56
6.1 Value of Shipments of Asbestos Friction Materials 61
6.2 U.S. Manufacturers of Asbestos-Bearing Friction Materials 63
6.3 Binders and Property Modifiers in Automotive Brake Linings 77
6.4a Average Brake Lining Composition 79
6.4b Brake Lining Compositions from Patent Literature 80
6.5 Summary of Published Data - Asbestos Emissions from Brake 83
Lining Use
6.6 Estimated Asbestos Emissions by Jacko and DuCharme (1973) 92
from Vehicles
x
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List of Tables (Cont'd)
Number Page
6.7 Estimated Asbestos Emissions from Vehicles Using Rohl et_ al. 93
(1976) Figures for Asbestos Content cf Wear Debris
6.8 Asbestos Concentration During Automobile and Truck Brake 98
Service
6.9 Asbestos-Free Composition of a Disc Brake Pad 102
6.10 Estimated Annual Environmental Release of Asbestos from 103
Friction Material Manufacture
7.1 Shipment Value and Quantity of Asbestos-Cement Pipe 109
7.2 Major U.S. Manufacturers of Asbestos-Cement Pipe 110
t
7.3 Estimated Annual Environmental Release of Asbestos from 114
A-C Pipe Manufacture
8.1 Shipment Values of Asbestos-Cement Sheets 135
8.2 Major Manufacturers of A-C Sheet 136
8.3 Estimated Annual Environmental Releases of Asbestos from 137
A-C Sheet Manufacture
9.1 Major U.S. Manufacturers of Asbestos Roofing 146
r
9.2 Shipment Values and Quantities of Asbestos Roofing Materials 148
9.3 Estimated Environmental Release of Asbestos from Asbestos 156
Roofing Production
10.1 1976 Asbestos Consumption in Paper Products 165
i
10.2 Quantity and Cost of Asbestos Used in Paper and Millboard 167
Products
10.3 Major Manufacturers of Asbestos Paper 168
10.4 Estimated Annual Environmental Releases of Asbestos from 171
Paper Manufacture
10.5 Asbestos Fibers in Beverages and Water 178
11.1 Shipment Values and Quantities of Asbestos Floor Products 183
11.2 Major U.S. Manufacturers of Asbestos Flooring 185
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List of Tables (Cont'd)
Number Page
12.1 Distribution of Asbestos Minerals Used for Insulation 196
12.2 U.S. Manufacturers of Asbestos Paper, Millboard, and Spun 197
Fiber Adaptable for Insulation
12.3 Value of Asbestos Insulation Products 198
12.4 Environmental Release of Asbestos from the Manufacture and 205
Installation of Insulating Materials
12.5 Comparison of Asbestos with Other Insulating Material 212
13.1 Major U.S. Manufacturers of Asbestos Gaskets, Packings 215
13.2 Distribution of Asbestos Mineral Used for Packing and Gaskets 214
13.3 Shipment Values of Asbestos Gaskets and Packing 217
13.4 Environmental Release of Asbestos from Manufacture of Gasket 221
and Packing Materials
14.1 Percentage of Asbestos Content by Weight in Asbestos Textile 229
Products
14.2 Distribution of Asbestos by Grade and Type 1976 230
14.3 Distribution of Quantity and Values of Textile Uses 231
14.4 Approximation of Release of Asbestos to the Environment 236
During Textile Manufacture
15.1 Distribution of Asbestos Minerals Used for Coatings, Paints, 242
and Sealants
15.2 Approximation of Asbestos Released to Environment from Coating 249
and Painting Compound Applications
15.3 Comparisons of Various Asbestos with Other Material 250
17.1 Asbestos Consumption of Specific Miscellaneous End-Uses 263
17.2 Types of "Patching Compound" by Application 266
17.3 Asbestos Fiber Concentrations During Use of Patching, Joint, 269
and Tape Compounds
xii
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List of Tables (Cont'd)
Number Page
18.1 Asbestos Fiber Usage for Each Industry Segment in 1976 281
18.2 Environmental Disposals and Releases of Asbestos from 282
Manufacturing
19.1 Results of Screen Sample Analysis of Total Fiber and Chryso- 292
tile Asbestos
19.2 Results of Screen Sample Analysis of Total Fiber and Chryso- 293
tile Asbestos
19.3 Results of Screen Sample Analysis of Total Fiber and Chryso- 29A
tile Asbestos in Coal Mining
xiii
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LIST OF FIGURES
Number
2.1
2.2
3.1
3.2
4.1
4.2
5.1
5.2
5.3
6.1
6.2
6.3
6.4
6.5
7.1
9.1
9.2
9.3
9,4
10.1
11.1
12.1
14.1
Schematic Diagram of the Structure of a Chrysotlle Fibre
Formed of Several Scrolls of Individual Crystallites
Schematic Diagram of the Crystal Structure of an Amphlbole
Fiber, Indicating the Unit Cell Based on X^igO^ (OH)2
Asbestos Industry Structures
Asbestos Products Industry
Asbestos - Salient Statistics
U.S. Asbestos Demand and Projected Trends to 2000
Possible Areas of Asbestlform Minerals
Asbestos Mines in the United States
Quebec Production Trends, From Analysis of 1951 - 1970 Data
Geographical Dispersion of U.S. Friction Materials Plants
Dry-Mixed Brake Lining Manufacturing Operations
Wet-Mixed Molded Brake Lining Manufacturing Operations
Molded Clutch Facings Manufacturing Operations
Woven Clutch Facings Manufacturing Operations
Asbestos-Cement Pipe Manufacturing Operations, Wet Mechanical
Process
Asbestos Roofing Manufacturing Operations
Asbestos-Cement Sheet Manufacturing Operations, Dry Process
Asbestos-Cement Sheet Manufacturing Operations, Wet Process
Asbestos-Cement Sheet Manufacturing Operations, Wet
Mechanical Process
Asbestos Paper Manufacturing Operations
Asbestos Floor Tile Manufacturing Operations
Asbestos Millboard Manufacturing Operations
Flowsheet of a Typical Asbestos Textile Plant
Page
4
5
20
21
31
49
54
55
58
67
70
72
73
75
112
150
152
153
154
170
187
201
227
xiv
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LUt of Figure* (Cont'd)
Muaber
14.2 Strength Retention of Plain (Man-Metallic) Aabeatoe Textile* 228
After 24-Hour Exposure to Teaperaturea of 400*9 600*9 end
800*7
14.3 Aebeetoe Textile Operation 233
16.1 General Procees Flow for Manufacture of Aebeetoe-Reinforced 256
Plaetice
17.1 A Circulatory Syatea for a Rotary Drilling Rig 274
xv
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1.0 INTRODUCTION
This study on the commercial market and environmental sources of asbestos
was undertaken for the following reasons: (a) to consolidate the large volume
of published literature in an attempt to describe the asbestos industry and the
uses of asbestos in terms of marketing data and statistics, (b) to examine the
potential for asbestos emissions from product manufacturing and product use, and
(c) to quantitatively estimate asbestos emissions to the environment where
possible. To date, no comprehensive attempt has been made to examine the sources
and quantities of asbestos which may be released to the environment from asbestos-
containing products as they relate to both their manufacture and use. Emission
estimates are projected from available monitoring data and engineering assump-
tions.
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2.0 DESCRIPTION OF ASBESTOS
2.1 Composition and Properties of Asbestos
"Asbestos" is not the name of a distinct mineral species but is a
commercial term applied to fibrous varieties of several minerals differing
widely in chemical composition, the fibers being diverse in length, strength,
flexibility, and consequent usefulness (The Asbestos Factbook, 1970). Gary
et al. (1972) define asbestos as:
11 (1) A commercial term applied to a group of highly fibrous
silicate minerals that readily separate into long, thin,
strong fibers of sufficient flexibility to be woven, are
heat resistant and chemically inert, and possess a high
electric insulation, and therefore are suitable for uses
(as in yarn, cloth, paper, paint, brake linings, tiles,
insulation, cement, fillers, and filters) where incombusti-
ble, nonconducting, or chemically resistant material is
required; (2) A mineral of the asbestos group, principally
chrysotile (best adapted for spinning) and certain fibrous
varieties of amphibole (esp. tremolite, actinolite, and
crocidolite); (3) A term strictly applied to the fibrous
variety of actinolite."
The American Society for Testing and Materials (ASTM) has provided
the following definition:
"Asbestos is a generic term for a number of naturally
occurring hydrated silicate fibers that, when crushed
or processed, separate into flexible fibers made up
of fibrils. Such materials are asbestiform. Minerals
included in this definition of asbestos are the asbesti-
form varieties of serpentine (chrysotile), riebeckite
(crocidolite), cummingtonite (amosite), anthophyllite,
tremolite, and actinolite."
Another definition of asbestos was established by the Occupational
Safety and Health Administration (OSHA) and appeared in the Federal Register
(10/9/75, p. 47652, 47660). In this regulatory statement, the naturally
occurring minerals chrysotile, amosite, tremolite, crocidolite, actinolite, and
-------
anthophyllite are specifically mentioned. These minerals are classified as
"asbestos" if the individual crystallites have the following size character-
istics: length - greater than 5 ym; maximum diameter - less than 5 ym; and a
length-to-width diameter ratio of three or greater. Material containing any of
the above minerals with the listed size characteristics will be defined as
"asbestos." Sometimes the literature refers to the common asbestoses with
jargon names: "white asbestos" for chrysotile and "blue asbestos" for crocldo-
lite (Berger and Oesper, 1963).
While the asbestoses differ in chemical composition, they share
similar polymeric silicate structure. The flbrlle-like structures of the
asbestoses result from linear chains of silicate tetrahedra. Chrysotile and
amphibole asbestoses fundamentally differ by the number and shape of the sili-
cate units. These differences can be visually identified from Figures 2.1 and
2.2, which are structure schematics of chrysotile and amphibole, respectively.
Chrysotile consists of Si.O. silicate units arranged in double layers and formed
into a laminar structure. The chrysotile SijO, layers are joined by brucite
(magnesium hydroxide) layers. This double layered structure is contorted in
tubes in which the brucite forms the outer fiber layer. The amphlboles contain
silicate as Si.O.. double chains in a banded structure. The chains are united
by Intercalated cations and form as solid fibers (Berger and Oesper, 1963;
Badolette, 1963; Kover, 1976).
Unlike the synthetic chemicals which usually exhibit unique chemical
compositions, the asbestoses are composed of mixed inorganic oxides. The vari-
ous asbestoses are characterized by ranges of these oxides rather than precise
molecular formulas. Table 2.1 below gives the approximate chemical formula for
-------
Plgur* 2.1, 8ch«ro«tlf Diagram of the Struct urn of a ChrynolJlu fll/ro Kor/mul
of Several Scroll a of Individual Cryatallltaa (Bach acroll in
formad from a cloatly connnctud doubla layar having magnaaium
hydroxide unita on ita axturnal faca and alliea unita on ita
innar faca. Tha dataila of a amall aaction of tha acroll ahow
tha atructura of tha doubla layar and of tha unit call baaad on
Mg3(8i205) (OH)4.) (Kovar, 1976)
-------
I OMVfttN
4 111 ICON
4
CATION
4 OdVOIN TMVBWDW
4 IK: (COM
/ OMVOIN
Fifurt 2,2, fehniAtic DUfriffl of th« Cryital »tructur« of *n Aophlbola Plt»«r,
Indicttini th« Unit C«ll l*Md on X7fi|022 (OM>2 (Th» line A-A
r«pr«itflti th« «dg» of th« pr«f§rr«d C!MV«M pl«n« Along which
tha fibril will iplit to form «v«n tmalUr fibr«§.) (Kov«r, 1976)
-------
each of the varieties of asbestos, while Table 2.2 lists the typical ranges of
mixed oxide compositions for the asbestoses.
Table 2.1. Approximate Chemical Formula of the Asbestoses
(The Asbestos Factbook, 1970)
Chrysotile 3MgO 2810, 2H20
Crocidolite Na20 Fe^ 3FeO 8Si02
Amosite l.SMgO 5.5FeO 8Si02 H
Anthophyllite TMgO 8S102 H_0
Tremolite 2CaO 5MgO
Actinolite 2CaO 4MgO FeO 8S102
Since asbestos is a metamorphic mineral, its composition reflects the composi-
tion of the surrounding minerals and its formation conditions. Therefore, the
oxide composition range differs for asbestoses of different geographical origin,
as evident from Table 2.3. The asbestoses contain relatively few elements. In
addition to silicate and water, they generally contain the oxides of magnesium,
calcium, iron, and/or sodium. Aluminum and potassium oxides are sometimes
present as trace "impurities." The "impurities" are defined as the oxides which
are not accounted in the approximate chemical composition. They can either form
part of the polymeric structure or occur as occlusions within the fibers (Berger
and Oesper, 1963).
Table 2.4 describes some of the properties Important in the commercial
uses of asbestos. The properties of asbestos that give it commercial value are
-------
Table 2.2. Chemical Composition of Common Fibrous Silicate Minerals (Rover, 1976)
Typical ranges,
Chrysotile
Crocidolite
Amosite
Anthophyllite
Actinolite
Tremolite
Si02
38-44
49-53
49-53
56-58
51-56
55-60
MgO
40-43
0-3
1-7
28-34
15-20
21-26
FeO Fe2°3
0-0.8 0.5-4
13-20 17-20
• OA_A A _____
3—17 _____
5-15 0-3
0-4 0-0.5
A1203
0.3-0.9
0-0.2
—
0.5-1.5
1.5-3
0-2.5
wt-%
CaO
0-1.0
0.3-2.7
10-12
11-13
K2°
Trace
0-0.4
0-0.4
0-0.5
0-0.6
Na2°
Trace
4-8.5
Trace
0.5-1.5
0-1.5
H20
13-14
2.5-4.5
2.5-4.5
1-6
1.5-2.5
0.5-2.5
-------
00
Tablo 2.3. Chemical Composition of Asbestoses from Different Geographic Locations
(The Asbestos Factbook, 1970)
Vi"'';lv FeO Fe,0,
, ""•' S102 (Ferrous (Ferric Al,0-
LorMll..,i (Silica) Oxide) Oxide) (Alu.lfia)
Chry«,,l < u
(Quebrt-1 A0 2 j „ 0 5 2 9
ChryKoitl,.
(So. Rh,M*«i«) 59. 7 0.7 0 3 3 2
Chrysot \\f
(Ural N:,O 38 j l 3 1>4 5 „
(Capo V-.-vtncc) 50.9 20.5 16.9 nil
Croc • „'.••. .;,.
(Ausir^.-.s> 5, e 14 , 18 6 0 2
CrociJo: -.;<.
(Bolivia • 55 7 3g n 0 AQ
Anoslte
(Transvja'.' 49-4 40 6 „ j ni]
(Flnlj:;v. S9 , 6 ? 10 Q9
Tre«c-l : . .
(PakU-.j. s^x 2 Q Q 3 j ^
Actlnoi • • .
(Cap. »:w .^ 53 „ 25 3 2() 12
HnO Na20 KjO H,0- H20+
MgO CaP (Manganese (Sodium (Potassium (Combined (Combined
(Magnesia) (Lime) Oxide) Oxld<0 Oxide) Water) Water)
39.9 1.1 0.1 0.1 0.1 O.B 13.4
40.3 1.1 0.3 0.1 0.1 0.6 12.2
37.7 2.2 0.1 0.1 0.1 0.8 11.1
1.1 1.5 0.1 6.2 0.2 0.2 2.2
4.6 1.1 Trace 6.0 0.1 0.2 2.8
13.1 1.5 Trace 6.9 0.4 Trace 1.8
6.7 0.7 0.7 0.1 0.2 0.1 1.9
29.7 0.1 0.2 0.1 0.1 0.5 2.4
25.7 11.5 0.1 0.3 0.2 3.5 0.2
4.3 10.2 0.4 0.4 0.1 0.2 2.6
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Table 2.4. Physical, Chemical, and Mineralogical Properties of Varieties of
Asbestos (Kover, 1976)
Property
CfMfninl
formula
pM
Reshnnrato
acids
VVIIMAf
Color
Ttxtun
Luster
Hardness*
Flexibility
Spinnibility
Tensile
• J !• II Mill
IUWIU.UI.
Ib. in.2
,-^** i
Fusion
pohtt'F
Specific heat.
Btu/lb.°F
ChryietUi
Mg,Si20B(OH)4
9.2 to 9.8
FOOT
Crass and
ilip titan
Green, o/ey.
jnbfr to
white
Soft to harsh.
also silky
Slkv
2.5lo 4.0
H*
V.rvBOOd
824.000 m»«.
2.770
0.266
CroddoMw
Ni2F*,a,02j(OH)2
—
Good
CrOHlHMr
Btut
Soft to harsh
Silky to duN
4
Good
Fair
876.000 max.
2.180
0.201
Amotttt
(FtMg)7Slg022(OH)2
—
—
CroalitMT
Gray, ytllaw
to dark
L.
Uf UHII
Coarwbut
tonwwhat
pliaW*
Vitrtoui.
Mmcwhit
Pt«rty
5.5 to 6.0
Good
Fair
16.000 to
90.000
2.560
0.193
Anthoptiyllte
|FtMo)7Si,022«OH)a
Ntutral
—
Sip. mi*
fiber unoritnttd
and intarlacing
Villowilh
brown, grtyiin
• whiM
Hanh
Vitrtouito
ptarty
6.510 6.0
Poor
Poor
4.000
and Ins
2.675
0.210
T«A«BMll4lB
iMnnm*
C^zMg,8i|022(OH)t
—
Good
Slip or
m*u fibir
Gray-whin.
ontnish. ytllowish,
Wuiih
Centrally
harsh.
somttimes
•oft
Silky
5.5
Poor
Poor
1.000W
8,000
2,400
0.212
Actinolit*
(CaMaF«)sSit022(OH)2
•-
Good
Slip or
mtu fiber
Greenish
Harsh
Silky
6±
Poor
Poor
1.000
ano lest
2£AQ
0.217
forking Scale of Hardness: 1 - very easily scratched by fingernail, and has
greasy feel to the hand; 2 - easily scratched by fingernail; 3 - scratch by
brass pin or copper coin; 4 - easily scratched by knife; 5 - scratch with
difficulty with knife; 6 - easily scratched by file; 7 - little touched by
file, but will scratch window glass. All harder than 7 will scratch window
glass.
-------
Table 2.4. Physical, Chemical, and Mineralogical Properties of Varieties of
Asbestos (Cont'd)
Property
Electric
charge
Filtration
properties
Specific
gravity
Cleavage
Optical
properties
Refractive
index
Resistance to
destruction
by heat
Temperature
at ignition
loss.°F
Magnetic
content.%
Crystal
structure
Crystal
system
Mineralogical
structure
Mineral
association
Chrvtotito
Positive
Stow
2.4 TO 2.6
010 perfect
Biaxial positive.
extinction
parallel
1.50 to 1.55
Good, brittle
at high
temperatures
1.800
00 to 50
Fibrous and
asbestiform
Monoclinic and
orthorhombic
In veins of
serpentine, etc.
In altered
peridotitt
. adjacent to
serpentine
and limestone
near contact
with basic
igneous rocks
Crocidolita
Negative
FM
3.2to 3J
110 perfect
Biaxial ±
extinction
inclined
1.7
pttochroic
Poor, fuses
1,200
3.0 to 5.9
Fibrous
Monoclinic
Fibrous in
iron stones
Iron rich
silicious
argillite
in quartzote
schists
Amosite
Negative
Fast
3.1 to 3.25
110 perfect
Biaxial positive.
extinction
parallel
1.641
Good, bum*
•thigh
tint pern unit
1.800 to 1. BOO
0
Prismatic,
lamellar to
fibrous
Monoclinic
Lamellar,
come to
fine fibrous
and asbestiform
in crystalline
schists, etc.
Anthophyllite
Negative
Medium
2.86 to 3.1
110 perfect
Biaxial positive.
extinction
parallel
1.6U
Very good
1.600
0
Prnmatic,
limcllir to
fibrous
Orthorhombic
Lamellar,
fibrous
asbestiform
In crystalline
schists and
gneisses
Tremolite
Negative
Medium
2.9to 3.2
110 perfect
Biaxial negative.
extinction
inclined
i
1.61t
Fair to good
1.800
0
Long and thin
columnar to
, fibrous
Monoclinic
Long, prismatic
and fibrous
aggregates
In Mg limestones
as alteration
product of
magnasian
rocks, metamorphic
and igneous
rwfcl
Actirtolite
Negative
Medium
3.010 12
110 perfect
Biaxial negative.
extinction
inclined
1.63*
weakly plcochroic
i.
i '
-.4 -
Long and thin
columnir to
fibrous
Monoclinic
Reticycted
long prismatic
crystals and
fibers
In limestones and
in crystalline
schists
10
-------
its fibrous structure, the great strength of its fibers, and its resistance to
high temperatures and to certain types of chemical attack.
Chrysotile asbestos excels commercially due to its fineness of fiber,
high flexibility, good heat resistance, general workability, and ample supply.
The longer fibers can be spun easily into textile materials. However, chryso-
tile degrades faster than the amphlboles in water, acids, or alkalis. This
results from the solubility and reactivity of the brucite. While amphiboles
lose only ca. 9% of their weight in 4N HCl after eight hours at 100°C, chryso-
tile looses all magnesium hydroxide (60% of its weight) after only one hour in
1 N HCl at 95°C (Berger and Oesper, 1963). When chrysotile is extracted by the
Soxhlet procedure for four hours with aqueous alkali (pH 10.33), it loses a high
percentage of magnesium ion and yields magnesium silicate. Crocidolite, when
treated by the same conditions, will leach only 4% silica and 6% sodium (Berger
and Oesper, 1963). Because crocidolite and amosite fibers are highly acid-
resistant, they are particularly valuable for use in chemical plant applica-
tions. Anthophyllite asbestos and tremolite asbestos fibers are too brittle to
be spun or used as fibrous reinforcements but, because of their resistance to
attack by certain chemicals, are used for filtering purposes in chemical process-
ing plants and in laboratories.
Since asbestos is often used in the manufacture of insulation for
electrical equipment, its electrical conductance is an important property. Its
•
conductance is related to the magnetite (Fe.O.) content. As the content of
this impurity increases, the asbestos-conductance also increases (Berger and
Oesper, 1963).
11
-------
The thermal stability is limited by asbestos metamorphosis to other
mineral forms. The fusion points listed in Table 2.4 are not melting points
for the asbestoses, but correspond to the fusion temperature of the metamorphic
products. Chrysotile, for example, is thermally transformed to the minerals
olivine or enstatite at a rate dependent upon time and temperature. The trans-
formation may be important to assess some environmental losses for certain
uses, such as in brake linings (Berger and Oesper, 1963).
2.2 Asbestos Grading
Asbestos is graded by fiber length. It is not commonly graded by
tnineralogical content or other properties. The Quebec Standard for chrysotile
is the most important, because most asbestos consumed in the U.S. is graded
by this system. The Quebec Standard measures the distribution of fibers after
sieving a 16 ounce sample through a system constructed of four boxes: three
screens and a "pan" for fines:
Box Number Screen Opening Diameter ofWire
1 0.500" 0.105"
2 0.187" 0.063" (4 mesh)
3 0.053" 0.047" (10 mesh)
Asbestos fibers are graded in nine groups: Groups No. 1 and 2 are hand-cobbled
crudes and the remainder are milled fibers. Group No. 1 is basically 3/4" staple
and longer fibers, which makes the best spinning grade. Group No. 2 includes
spinning fibers of lower quality. The milled fibers are grouped according to
the box distributions listed in Table 2.5 (Berger and Oesper, 1963; The Asbestos
Factbook, 1970).
Other grading systems are also used for chrysotile and the amphlbole
asbestoses. They also grade fibers by length. U.S. mined asbestos basically
12
-------
Table 2.5. Chrysotile Grades by the Quebec Standard Test
(The Asbestos Factbook, 1970)
Standard Grade Designation
Fiber Description
Group No. 1, Crude No. 1
Group No. 2, Crude No. 2
Group No. 2, Crude run-of-mine
Group No. 2, Crudes sundry
Groups No. 3 through No. 9
- consists basically of crude 3/4"
staple and longer
- consists basically of crude 3/8"
staple up to 3/4"
- consists basically of unsorted
crudes
- consists of crudes other than
above specified
- are "Milled Asbestos"
Guaranteed Minimum Shipping Test
(Distribution of 16 oz. of Fibers)
Box 1 Box 2
Box 3
Pan (fines)
Group No. 3:
Group No. 4:
Group No. 5
3F
3K
3R
3T
3Z
4A
4D"
4H
4J
4K
4M
4R
4T
4Z
5D
5K
5M
5R
5Z
10.5
7.0
4.0
2.0
1.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
3.9
7.0
7.0
8.0
9.0
8.0
7.0
5.0
5.0
4.0
4.0
3.0
2.0
1.5
0.5
0.0
0.0
0.0
0.0
1.3
1.5
4.0
4.0
4.0
6.0
6.0
8.0
7.0
9.0
8.0
9.0
10.0
9.5
10.5
12.0
11.0
10.0
8.6
0.
0.
1,
2.
2.0
2.0
3.0
3.0
4.0
3.0
4.0
4.0
4.0
5.0
5.0
4.0
5.0
6.0
7.4
13
-------
Table 2.5. Chrysotile Grades by the Quebec Standard Test (Cont'd)
Group No. 6
Group No. 7
Group No. 8
6D
7D
7F
7H
7K
7M
7R
7T
7W
8S
8T
Box 1
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
under 50
under 76
Box 2 Box 3 Pan (fines)
0.0 7.0
0.0 5.0
0.0 4.0
0.0 3.0
0.0 2.0
0.0 1.0
0.0 0.0
0.0 0.0
0.0 0.0
Ibs/cubic foot
Ibs /cubic foot
9.0
11.0
12.0
13.0
14.0
15.0
16.0
16.0
16.0
loose measure
loose measure
Group No. 9
9T
over 75 Ibs/cubic foot loose measure
14
-------
follows the Quebec Standard. Table 2.6 describes the modifications used for
Arizona mined asbestos.
2.3 Major Uses of the Asbestoses
The following discussion briefly describes the major uses for the
asbestoses and the reasons why they are used. Market input/output data con-
cerning the quantities consumed according to use and grade are given in Sec-
tion 4.0.
2.3.1 Chrysotile
Chrysotile dominates the asbestos consumed in total quantity,
value, and number of products. It accounts for about 95% of all the asbestos
commercially consumed.
(a) Asbestos Textiles
The long Chrysotile fibers (Grades No. 1, 2, and 3) are pre-
dominantly used for textile manufacture. The textile products can eventually
be marketed as textiles such as safety clothing, drapes and curtains, wicks,
etc. or they can be further processed with resins and other additives in the
manufacture of friction materials, gaskets, laminated plastics, etc. (Kover,
1976; Hendry, 1965; The Asbestos Factbook, 1970; Clifton, 1975).
(b) Asbestos Cement
Medium sized Chrysotile fiber (Groups No. 4 to 7) dominate
in production of asbestos cement products (pipe and sheet). Asbestos cement
products account for the major portion of the asbestos consumption, both in
tonnage of fiber and market value. The properties which contribute to its
commercial position include fiber length and tensile strength (Kover, 1976;
Carton, 1974; Berger and Oesper, 1963; Clifton, 1976).
15
-------
Table 2.6. Modifications in Grading American Mined Asbestos
(The Asbestos Factbook, 1970)
ASBESTOS GRADES IN ARIZONA
Source: Metate Asbestos Corporation, Globe, Arizona
Fhc same "Guaranteed Minimum Shipping Tests" arc used in Arizona as arc used
in ("anada. with the following exceptions
3Z (Soft I iller Grade) is held to 01042
Special Sugar Grade LX-222-NAW is
held to about Canadian Grade 3T 2842
All other Ari/.ona Grades follow Canadian grading procedures but add the
following designations:
S Soft
H - Harsh
AW - Acid Washed
NAW Non-Acid Washed
16
-------
(c) Asbestos Paper and Felt
Properties for which chrysotile is used in this product segment
include its capacity for heat and electrical insulation, its chemical and
thermal stability, its strength and flexibility (Kover, 1975; Carton, 1974;
Hendry, 1965). Chrysotile grades from 3 to 7 are predominantly used (Berger and
Oesper, 1963; Clifton, 1975).
(d) Composition Materials
The composition materials include plastics, asbestos-vinyl and
asbestos-asphalt products, coatings, and compounds. Chrysotile is added to
these products generally as a filler and reinforcement medium (Modic and Barsness,
1965; Seymour, 1968; Grove and Rosato, 1967). The longer fibers (including
Grades No. 1 and 2) are used in the production of high grade laminated plastics.
The short fibers (Grades No. 4 and shorter) dominate in the manufacture of most
other composition materials (Clifton, 1975; Berger and Oesper, 1963). Although
the quantity of fibers used in these products is large (the second largest
consumption of fibers), the low value of the short fibers results in a low
comme'rcial value for asbestos used in this market segment.
(e) Friction Materials
The properties for which asbestos is used.in friction materials
include its capacity for thermal stability, its ability to act as a reinforcing
agent, as a filler, for the regulation or inhibition of resin flow, its lower
abrasion than other fillers of its price range, and its dispersion of metal
chips and other particulates (Hendry, 1965). While the fiber lengths of Grades
No. 4 to 7 dominate the friction materials, some longer fibers are also used
(Clifton, 1975).
17
-------
(f) Packing and Gaskets
Chrysotile use in packings and gaskets is accounted for by its
strength, resiliency, durability, toughness, and thermal stability (Hendry,
1965; Kover, 1976). Fiber length predominantly ranges from Grades No. 4 to 7,
although some Grades 1 through 3 are also consumed (Clifton, 1975; Berger and
Oesper, 1963; SRI, 1974).
2.3.2 Crocidolite
Crocidolite fibers are shorter and more brittle than chrysotile
but have a slightly higher tensile strength. Crocidolite is principally con-
sumed for the manufacture of asbestos cement products (Kover, 1976; Clifton,
1976). While it can be spun into fibers, its spinnability is not equivalent to
chrysotile. Longer Crocidolite fibers are sometimes mixed with chrysotile for
textile production (Berger aud Oesper, 1963). It is used as replacement for
chrysotile fibers in some laggings, insulations, filter media, and packings
exposed to corrosive (acid or alkali) substances (Fisher, 1967; Hendry, 1965;
Kover, 1976). Long Crocidolite fibers are also consumed in asbestos boards and
papers (Berger and Oesper, 1963).
2.3.3 Amosite
Amosite has lower tensile strength than chrysotile or crocidolite
by more than an order of magnitude. It is consumed mainly in asbestos cement
products. Other major uses are in various thermal insulations, including pipe
and boiler coverings, bulkhead linings in ships, and 85% magnesia insulation
(Hendry, 1965; Kover, 1976).
2.3.4 Tremolite and Actinolite
Both tremolite and actinolite asbestoses are of low tensile
strength and are brittle. They have only minor commercial use. They are
18
-------
primarily consumed as cheap fillers and as filtering mediums. Tremolite is
sometimes purified by acid treatment for special filtering purposes (Kover,
1976; Hendry, 1965).
2.3.5 Anthophyllite
Anthophyllite asbestos is also of minor commercial value. It is
mainly used as a filler in rubber, plastics, adhesives, and asbestos cement
products (Kover, 1976; Hendry, 1965; Clifton, 1975).
19
-------
3.0 DESCRIPTION OF THE ASBESTOS INDUSTRY
3.1 Industry Structure
Figure 3.1 below is a simple illustration showing the movement of
asbestos within the asbestos industry.
Mining » Milling ^Primary >Secondary ^Consumer
Industries Industries Industries
-^Consumer
Industries
Figure 3.1. Asbestos Industry Structure
The following definitions have been adopted (Daly et al., 1976):
Primary Industries; those industries that start the manufacturing process with
raw asbestos fiber and modify the fiber to produce an intermediate product (to
be further processed or fabricated) or a finished product.
Secondary Industries; those industries that continue the manufacturing process
with an intermediate asbestos product (one in which the fiber has previously
been modified in a primary industry), and further process, modify, or fabricate
it to produce either another intermediate product (to be further processed or
fabricated) or a finished product.
Consumer Industries: those industries that purchase a finished asbestos-
containing product (from a primary or secondary industry), and apply, install,
erect, or consume the asbestos-containing product without further physical
modification of the product.
This classification is depicted in Figure 3.2, which categorizes the
various end uses by products.
20
-------
Primary Industries
Secondary Industries
FLOOR TILE
GASKETS ft PACKINGS
FRICTION PRODUCTS
PAINTS. COATINGS & SEALANTS
ASBESTOS REINFORCED PLASTICS
ASBESTOS CEMENT PIPE
ASBESTOS TEXTILES
OFFICE. HOME. COMMERCIAL FLOORS
VALVt. FLANGE. PUMP. TANK SEALING COMPONENTS
ClUTCH/TRANSMISSraM. BRAKE COMPONENTS
INDUSTRIAL FRICTION MATERIALS
AUTOMOTIVE/TRUCK BODY COATINGS
ROOF COATINGS AND PATCHING COMPOUNDS
ELECTRIC MOTOR COMPONENTS
MOLDED PRODUCT COMPOUNDS FOR NIGH STRENGTH/WEIGHT USES
CHEMICAL PROCESS PIPING
WATER SUPPLY PIPING
CONDUITS FOR ELECTRICAL WIRES
ASBESTOS PAPER
ASBESTOS CEMENT SHEET
PACKING COMPONENTS
GASKET COMPONENTS
ROOFING MATERIALS
COMMERCIAL INDUSTRIAL DRYING FELTS
HEATfFIRE PROTECTIVE CLOTHING
CLUTCH/TRANSMISSION COMPONENTS
ELECTRICAL WIRE AND PIPE INSULATION
THEATER CURTAINS AND FIREPROOF DRAPERIES
GAS/VAPOR DUCTS FOR CORROSIVE COMPOUNDS
FIREPROOF ABSORBENT PAPERS
TABLE PADS AND HEAT PROTECTIVE MATS
HEAT/FIRE PROTECTION COMPONENTS
MOLTEN GLASS HANDLING EQUIPMENT
INSULATION PRODUCTS
GASKET COMPONENTS
UNOERLAVMENT FOR SHEf T FLOORING
ElCCIRICWIRE INSULATION
FILTERS FOR BEVERAGES
APPLIANCE INSULATION
ROOFING MATERIALS
HOODS VENTS FOR CORROSIVE CHEMICALS
CHEMICAL TANKS AND VESSEL MANUFACTURING
PORTABLE CONSTRUCTION BUUOINOS
ELECTRICAL SWITCHBOARDS AND COMPONENTS
RESIDENTIAL BUILDING MATERIALS
MOLTEN METAL HANDLING EQUIPMENT
INDUSTRIAL BUILDING MATERIALS
FIRE PROTECTION
INSULATION PRODUCTS *
SMALL APPLIANCE COMPONENTS
ELECTRICAL MOTOR COMPONENTS
LABORATORY FURNITURE
COOLING TOWER COMPONENTS
MISCELLANEOUS
WHOLESALERS
Consumer Industries
ARC DEFLECTORS. ELECTRICAL-RESISTANCE SUPPORTS. WATER
SUPPLY AND SEWAGE PIPING. DECORATIVE BUILDING PANELS,
PLASTER AND STUCCO. MOLDED PLASTICS. ACOUSTICAL PRODUCTS.
SAPHALT PAVING. CAULKING. MOTOR ARMATURES. PAINTS.
AMMUNITION WADDING. WELDING-ROD COATINGS. DRIP CLOTHS.
FIRE DOORS. AUTOMOTIVE BRAKES AND TRANSMISSIONS.
HEATER ELEMENT SUPPORTS. OVEN AND STOVE INSULATION.
SIDING SHINGLES. AUTOMOTIVE GASKETS. ELECTRIC MOTOR
CASINGS. ELECTROLYTIC CELL DIAPHRAGMS. FLOOR TILES.
SPACE-VEHICLE HEAT SHIELDS, CORROSIVE-RESISTANT PIPING
AND DUCTS.MARINE BULKHEADS. TANKS FOR CHEMICALS.
FIRE HOSES. GARMENTS. GLOVES. FILTER MEDIA.
AUTOMOTIVE UNOERCOATINGS. BOILER INSULATION, FURNITURE.
PUMP AND VALVE SEALS. MOTION PICTURE SCREENS. ROOFING
PRODUCTS. MOLTEN-METAL CONVEYORS. RUGS. WALLBOARD.
POWER-CABLE INSULATION. ELECTRICAL SWITCHES
Figure 3.2. Asbestos Products Industry (Daly jrt
1976)
-------
The first industry segment to come into contact with the asbestos is,
of course, the mining segment. As far as the United States is concerned, how-
ever, this predominately occurs in Canada. From 1971 to 1975, between 80-85% of
the asbestos consumed domestically was imported (see Sections 4.3 and 4.4); and
of the imported asbestos, nearly 96% originated in Canada (Clifton, 1975). The
milling segment of the industry is very closely connected to the mining segment
because mills are usually located in close geographical proximity to the mines
and, in general, the mines and mills are owned and operated by the same parent
corporation. American mining and milling production is discussed in Section 5.1.
The interesting relationship is, however, the relationship between the
mining segment of the industry and the primary industries, the product manu-
facturers who initially fabricate asbestos products. Table 3.1 lists the cap-
tive fiber sources in Canada and in the U.S. for the major domestic asbestos
products manufacturing firms. Twenty of the largest U.S. asbestos products
manufacturers are listed in Table 3.2. When Tables 3.1 and 3.2 are compared, it
can be seen that four corporations (Johns-Manville, Raybestos-Manhattan, Jim
Walter, and ASARCO) not only control large mining interests in Canada, but also
control nearly 35% of the American asbestos products market.
According to the 1967 U.S. Census of Manufacturers, 81 firms operating
138 establishments were involved in asbestos products manufacturing (SIC 3292;
this does not include asbestos paper-making establishments). The 1972 Census of
Manufacturers lists 142 establishments for SIC 3292. When the asbestos paper-
makers are included, it is estimated that approximately 85 firms are presently
engaged in asbestos products manufacture (SRC estimate). In evaluating the
asbestos products manufacturing industry, it is possible to arrive at the
22
-------
Table 3.1. Captive Fiber Sources for the Major American Asbestos Product
Manufacturing Firms (Igwe, 1974; Asbestos Magazine, Dec. 1975)
Company
Canadian Mines
Mine (Company)
Fiber-Producing Capacity
(short tons/year)
ASARCO
Johns-Manvilie
Products Corp.
Jim Walter Corp.
Lake Asbestos of
Quebec, Ltd.
Canadian Johns-Manville
Co., Ltd.
Carey-Canadian Mines, Ltd.
Raybestos-Manhattan, Inc. Cassiar Asbestos Corp.
(partial interest)
General Dynamics Corp. Asbestos Corp., Ltd.
(54% interest)
150,000
835,000
200,000
110,000
500,000
Atlas Asbestos Co.
Union Carbide Corp.
Johns-Manville
Products Corp.
American Mines
Atlas Asbestos Co.
Union Carbide Mines
Coalings Asbestos Co.
25,000
10,000
(closed at present)
23
-------
Table 3.2. Twenty of the Largest U.S. Asbestos Product Manufacturers
(Economic Information Systems, 1976; Igwe, 1974; SRC Estimates)
Estimated 1975
Asbestos-Product "Sales
Company ($ millions)
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
Johns-Manville Corp.
Raybestos-Manhattan, Inc.
GAF Corp.
Bendix Corp.
Jim Walter Corp.
(Celotex)
Armstrong Cork Co.
Illinois Central
Industries (Abex Corp.)
Flintkote Co.
Asten-Hill Mfg. Co.
H.K. Porter Co.
Certain-Teed Corp.
Nicolet Industries
Ken tile Floors Inc.
National Gypsum Co.
Royal Industries
Uvalde-Rock-Asphalt Co.
Sabine Industries
American Asbestos Textile
ASARCO Inc.
240
140
114
72.5
71
60
60
50
40.5
37.6
33.1
30.7
29.5
27.1
24.5
21.6
21.6
15.0
13.0
*
Approximate Percentage
of the U.S. Market
18.0
10.5
8.5
5.5
5.5
4.5
4.5
3.5
3.0
3.0
2.5
2.0
2.0
2.0
2.0
1.5
1.5
1.0
1.0
(Cement Asbestos Products)
20. Gatke Corp. 11.6 1.0
24
-------
conclusion that the industry may be dominated by several giant firms. From
t
Table 3.2 it can be seen that the six largest firms control over 50% of the
market. It should also be noted that the larger asbestos-based manufacturing
firms are generally diversified into other product lines. Table 3.3 shows the
percentage of some major manufacturers' product lines that are related to
asbestos.
Table 3.3. Asbestos-Based Activity of Some Major Asbestos-Manufacturing Companies
(Igwe, 1974; SRC Estimates)
Estimated Annual Sales Percent of Product Line
Company ($ millions) Related to Asbestos
American Biltrite Rubber Co.
The Flintkote Co.
GAP Corp.
Johns-Manville Corp.
National Gypsum Co.
•
Jim Walter Corp.
161
441
800
519
880
5
12
5
30
5
8
3.2 Types of Plants
Asbestos products manufacturing plants are characterized by a high
degree of specialization. The typical plant (especially of the minor manufac-
turers) is apt to be a single-product operation whose product is geared to
service a specific Industry. Table 3.4 lists the general statistics for
25
-------
Table 3.4. Industry Specialization and Primary Product Class Specialization for
Asbestos Product Producing Establishments: 1972 (SIC 3292) (1972
Census of Manufacturers, U.S. Bureau of the Census)
Establishments
Establishments with 75%
or More
Specialization
Entire Industry
Primary Product Class
Friction Materials
Asbestos-Cement Shingles
and Clapboard
Vinyl Asbestos
Floor Tile
Asbestos and Asbestos-Cement
Products
142
23
7
18
55
127
21
6
17
42
establishment specialization in 1972. In Table 3.4 the measures of plant
specialization are shown as: (1) industry specialization - the ratio of primary
product shipments to total product shipments (primary plus secondary) and
(2) product class specialization - the ratio of the largest primary product
class shipments to total product shipments (primary plus secondary) for the
establishment.
A survey of selected facilities shows that nearly all the large plants
employing in excess of 100 workers belong to the major firms within the industry,
such facilities also often generating relatively minor proportions of non-
asbestos products (Igwe, 1974).
26
-------
It is fair to state that the asbestos manufacturing industry in the
United States is very mature, with most of the larger plants well over 25 years
old and employing well-established technologies. For instance, asbestos-cement
pipe manufacture was introduced in the United States about 1928 by the Johns-
Manville Corporation at its Waukegan, Illinois, plant. Except for incorporation
of sophisticated controls and materials handling systems, it is doubtful whether
the technology, similar in principle to that employed in the manufacture of flat
or corrugated sheeting, has changed to any fundamental extent since then. Simi-
lar comments may be applied to the manufacture of vinyl asbestos tiles (Igwe, 1974)
3.3 Numerical and Percentage Distribution of Plants, Employees, and
Production
The numerical distribution of the establishments by size (expressed
in terms of the number of employees) as given by the 1972 Census of Manufacturers
i
is shown in Table 3.5. Total employment as a function of establishment size and
total value of shipments as a function of establishment size for asbestos products
manufacturing are given in Table 3.6.
A comparison of Tables 3.5 and 3.6 shows that whereas establishments
with less than 100 employees account for 53.4% of the number of asbestos prod-
ucts manufacturing establishments, these facilities employ only 7.8% of the
work force. The relative minor contributions of the "less-than-100-employees"
facilities are further illustrated when Table 3.5 is compared to Table 3.6.
The industry segment with less than 100 employees per establishment contributes
only 6.1% of the shipment values of asbestos products. The economic punch appears
clearly to rest with the major manufacturing units.
There is the additional consideration that, for a given asbestos
product, the manufacturing equipment tends to be of a given standard capacity.
27
-------
Table 3.5. Asbestos Products Manufacture: Distribution, of Plant Sizes
(1972 Census of Manufacturers (SIC 3292), U.S. Bureau of the
Census)
Average Number Total Number
of Employees of Establishments Percent of Total
1 to 4
5 to 9
10 to 19
20 to 49
50 to 99
100 to 249
250 to 499
500 to 999
1000 to 2499
Total
12
20
13
16
15
40
19
5
2
142
8.5
14.0
9.1
11.3
10.5
28.2
13.4
3.5
1.4
28
-------
Table 3.6. Asbestos Products Manufacturing: Total Value of Shipments as a
Function of Size of Facilities (1972 Census of Manufacturers
(SIC 3292), U.S. Bureau of the Census)
Average Number Value of Shipments Percent of Total
of Employees ($ millions)
1 to 4
5 to 9
10 to 19
20 to 49
50 to 99
100 to 249
250 to 499
500 to 999
1000 to 2499
Total
0.7
4.9
7.4
15.8
30.7
246.8
255.6
201.5
200.0*
963.4
•v^
0.5
0.8
1.6
3.2
25.6
26.5
20.9
20.8
* SRC Estimate
Differences in plant capacities are therefore determined approximately by the
number of installed machines, and capacity differences therefore occur in multi-
ples of one standard machine capacity (Igwe, 1974).
29
-------
4.0 MARKET INPUT/OUTPUT DATA
The salient statistics for asbestos are graphed in Figure 4.1, which covers
the period from 1940 to 1976. Import and export data shown in Figure 4.1 repre-
sent shipments of unmanufactured asbestos only.
4.1 Mine Production
Table 4.1 lists the domestic and world mine productions from 1965 to
1976. U.S. mines shipped only 75% as much asbestos in 1974 as in 1973 and only
66% as much in 1975 as in 1973. The exact total output of 112,533 tons in 1974
was valued at $13,759,000 (Clifton, 1975).
Only four states produce asbestos: California, with 53% of the 1974
total, was the leader, followed in order by Vermont, Arizona, and North Carolina.
The California segment of the asbestos industry has led the sharp decline in
U.S. production. The closing, in early 1974, of Johns-Manville's (Coalings
Asbestos Co.) mine was followed by the closing of H.K. Porter's (Pacific Asbestos
Corp.) mine. These mine closures led to production of only 57% of the 1973
California state total, and only 55% of the 1973 dollar value of the fiber was
realized (Clifton, 1975). The H.K. Porter mine was sold in October, 1975, to
Calaveras Asbestos Ltd. and began operation in 1976 (Clifton, 1977).
All of the American mines produce the chrysotile variety of asbestos
except the North Carolina mines which produce the anthophyllite variety. In
total, the American mines produce approximately 15% of the asbestos used in the
United States. The remainder is imported, mostly from Canada (see Section 4.3).
30
-------
THOUSANDS OF SHORT TONS
i
1000
100 -
• I I I I • • • I
APPARENT CONSUMPTION
.IMPORTS (O)
DOMESTIC PRODUCTION
I li I l l i I l I l l I > i i i I
liiiiliiiiliiiiliiii
1940 1945 1950 1955 I960 1965 1970 1975 1980 1985 1990
Figure 4.1. Asbestos - Salient Statistics (SRI, 1974; Clifton, 1977; U.S. Bureau
of the Census, 1975 a, b)
31
-------
Table 4.1. Mine Production of Asbestos (Clifton, 1977)
(Thousand short tons)
1965 1966 1967 1968 1969 1970 1971 1972 1973 1974 197S 1976
World alne production:
United States
Rest of world
Total
118 126 123 121 126 125 131 132 ISO 113 99 115
2,984 3.149 3,084 3,170 4.042 3,672 3.816 4,050 4,448 4,423 4,410 4.885
3.102 3.275 3.207 3,291 4,168 3.797 3,947 4,182 4.598 4,536 4,509 5.000
ro
-------
4.2 Exports
Table 4.2 below lists the American export of asbestos (unmanufactured)
from 1965 to 1975.
Table 4.2. U.S. Export of Asbestos (Unmanufactured) for 1965 - 1976
(Clifton, 1977; U.S. Bureau of the Census, 1975 b)
Year Asbestos Export in Thousands of Short Tons
1976 47
1975 35
1974 " 62
1973 66
1972 59
1971 54
1970 47
1969 36
1968 41
1967 47
1966 47
1965 43
Tables 4.3a and 4.3b list the countries to which the exported asbestos
(unmanufactured) was shipped in 1975 and in the first half of 1976, respective-
ly, and the amounts shipped to each country. Unmanufactured asbestos includes
asbestos fibers, not further processed than beaten, washed or graded to length
and asbestos waste and refuse. Table 4.4 lists U.S. exports, by country, of
asbestos manufactured products in 1975.
In 1975 U.S. exports of unmanufactured asbestos amounted to only 6.5%
of the quantity of U.S. imports, while in 1974 the figure was only 8.1%. On
the other hand, the dollar value of U.S. exports of manufactured asbestos prod-
ucts was nearly three times higher than the dollar value of U.S. imports of
manufactured asbestos products.
33
-------
Table 4.3a. U.S. Export — By Country — of Asbestos (Unmanufactured) in 1975
(U.S. Bureau of the Census, 1975 b)
2764015 Asbestos fibers, not further processed than beaten,
washed, or graded to length
Net Quantity Value
(Short Tons) (Dollars)
Canada
Mexico
Brazil
Belgium
France
West Germany
Rumania
Iran
Singapore
Japan
Other Countries
Total
2764030 Asbestos waste and
Canada
Mexico
Colombia
Venezuela
Brazil
United Kingdom
France
West Germany
Italy
Iran
Singapore
Japan
Egypt
Other Countries
Total
1,567
6,881
699
463
206
937
494
721
1,137
1,334
734
15,173
refuse
3,629
5,109
706
391
115
815
458
723
120
203
615
3,842
104
2.918
19,748
682,546
2,349,846
261,080
140,181
204,242
335,709
101,420
252,817
523,255
936,115
279,895
6,067,106
188,856
1,151,572
124,078
70,978
67,123
131,681
101,436
202,087
72,414
78,240
577,569
700,350
64,558
460,943
3,991,885
U. S. Bureau of the Census, 1975b
34
-------
Table 4.3b.
U.S. Export — By Country — of Asbestos (Unmanufactured) from
January, 1976, to June, 1976 (U.S. Bureau of the Census, 1976 b)
2764015 Asbestos fibers, not further processed
or graded to length
Canada
Mexico
Venezuela
Brazil
United Kingdom
The Netherlands
Belgium
East Germany
Greece
Rumania
Iran
Thailand
Indonesia
Taiwan
Japan
Algeria
Other Countries
Total
2764030 Asbestos waste and
Canada
Mexico
Colombia
Venezuela
Brazil
United Kingdom
East Germany
Spain
Italy
Rumania
United Arab Emirants
Korean Republic
Japan
Algeria
Libya
Other Countries
Total
Net Quantity
(Short Tons)
448
4,883
119
63
41
298
328
177
126
371
140
1,320
900
300
1,532
840
595
12,481
refuse
255
5,430
445
231
378
613
400
120
49
400
192
1,500
3,507
760
149
646
15,075
than beaten, washed,
Value
(Dollars)
161,298
1,283,987
40,302
41,106
32,000
63,953
76,115
130,190
33,840
101,135
39,033
527,987
284,150
116,350
631,900
292,428
104,760
3,960,534
63,389
1,113,082
80,832
36,805
77,447
114,365
209,904
57,831
54,279
76,000
125,195
348,000
546,306
57,054
101,058
158,559
3.220,106
U. S. Bureau of the Census, 1976b
35
-------
Table 4.4. U. S. Exports—By Country—of Asbestos Manufactured Products in 1975
6618310 Asbestos-cement shingles
Canada
United Kingdom
West Germany
Italy
Saudi Arabia
Japan
Other Countries
Total
and clapboard
Net Quantity
(Pounds)
669,126
589,890
17,778,767
7,205,759
228,577
234,704
1,847,108
28,553,931
Value
(Dollars)
142,466
109,149
2,977,698
943,314
78,228
66,185
331,776
4,648,816
6618320 Articles of asbestos-cement or of fiber-cement except asbestos
cement shingles and clapboard
Canada
Mexico
Salvador
Panama
Brazil
Sweden
West Germany
Iran
Saudi Arabia
Indonesia
Philipine Republic
Japan
The Pacific Islands
Algeria
Republic of South Africa
Other Countries
Total
6638105 Asbestos gaskets
1 Canada
Jamaica
Iran
Saudi Arabia
Republic of South Africa
Other Countries
Total
21,936,513
487,372
455,804
5,266,390
134,606
305,303
102,004
265,941
4,511,035
33,478
360,441
418,104
320,865
2,094,038
116,300
1,096,502
37,904,696
172,100
32,955
39,551
91,663
14,105
184.962
535,336
3,867,321
138,980
64,879
715,851
70,184
375,555
87,175
79,733
999,724
161,793
70,893
242,323
71,806
185,964
73,093
422,609
7,627,883
500,993
98,785
68,213
202,404
79,183
660,608
1,610,186
U. S. Bureau of the Census, 1975b
36
-------
Table 4.4. U. S. Exports—By Country—of Asbestos Manufactured Products in
1975* (Cont'd)
6638115 Asbestos packing
2 Canada
Mexico
Guatemala
Jamaica
Colombia
Venezuela
Surinam
Peru
Chile
Brazil
Sweden
Finland
United Kingdom
Ireland
The Netherlands
Belgium
France
West Germany
Switzerland
Spain
Italy
Greece
Iran
Israel
Kuwait
Saudi Arabia
India
Pakistan
Thailand
Singapore
Philippine Republic
Korean Republic
Taiwan
Japan
Australia
New Zealand
Nigeria
Republic of South Africa
Zambia
Other Countries
Total
Net Quantity
(Pounds)
1,042,869
393,093
25,828
49,803
320,649
37,695
42,645
151,358
123,234
114,892
15,451
30,289
264,110
81,400
15,083
20,239
41,189
76,187
17,857
30,531
86,309
25,198
46,118
9,577
16,468
466,441
145,126
13,920
42,989
153,448
229,895
27,000
52,596
57,871
28,394
25,210
33,470
35,719
11,917
346,981
4,749,049
Value
(Dollars)
1,896,802
291,741
68,294
278,425
513,348
158,526
142,790
396,141
205,258
119,524
94,047
279,984
374,256
366,739
113,214
139,314
177,591
205,023
80,840
183,812
673,373
73,157
137,128
95,091
80,943
256,331
64,691
64,832
76,663
408,972
551,008
63,030
159,405
262,573
131,979
170,069
87,997
242,818
118,528
987,008
10,791,265
U. S. Bureau of the Census, 1975b
37
-------
Table 4.4. U. S. Exports—By Country—of Asbestos Manufactured Products in
1975* (Cont'd)
Net Quantity Value
(Pounds) (Dollars)
6638117 Asbestos insulation, heat or sound
2 Canada — 729,888
Mexico — 188,096
Dominican Republic — 60,990
Venezuela — 282,149
Surinam — 282,149
Peru -- 81,658
Brazil — 214,532
United Kingdom — 130,610
The Netherlands — 102,618
Belgium — 253,755
Iran — 66,323
Pakistan — 143,518
Singapore ~ 364,906
Philippine Republic — 74,620
Mainland China — 916,153
Japan ~ 98,572
Australia — 99,706
New Zealand — 248,444
Egypt — 68,333
Ghana — 65,383
Other Countries — 812.154
Total — 5,071,672
6638120 Asbestos textiles and yarns
3 Canada
Mexico
Peru
Sweden
United Kingdom
Ireland
The Netherlands
West Germany
Italy
Japan
Australia
Other Countries
Total
.7,749,305
1,249,110
122,520
122,929
85,929
45,100
487,222
195,984
54,043
23,646
1,020,703
307,061
11,463,552
3,664,189
747,770
220,267
230,746
207,598
145,350
127,799
252,944
274,700
146,510
614,452
651,974
7,284,299
U. S. Bureau of the Census, 1975b
38
-------
Table 4.4. U. S. Exports—By Country—of Asbestos Manufactured Products in
1975* (Cont'd)
Net Quantity Value
(Pounds) (Dollars)
6638150 Asbestos protective clothing
Mexico — 76,580
Greece . — 200,311
Saudi Arabia ~ 68,643
Other Countries — 463.975
Total — 809,509
6638160 Asbestos manufactures, other than friction materials, NEC
Canada — 2,230,745
Mexico — 246,573
Panama — 74,099
Jamaica — 70,179
Venezuela -- 749,761
Peru — 305,139
Chile — 182,659
Brazil — 83,043
Sweden — 1,145,722
United Kingdom — 2,528,018
The Netherlands — 702,650
West Germany — 866,848
Switzerland — 124,542
Poland — 81,315
Lebanon — 83,372
Iran — 66,238
Saudi Arabia — 185,369
Korean Republic — 110,313
Japan -- 439,217
Australia — 92,913
New Zealand — 200,613
Republic of South Africa — 325,572
Other Countries — 845.089
Total — 11,739,989
U. S. Bureau of the Census, 1975b
39
-------
Tabla 4.4. U. S. Exports—By Country—of Asbestos Manufactured Products
in 1975* (Cont'd)
Net Quantity Value
(Pounds) (Dollars)
6638202 Asbestos clutch facings for automotive use, including linings
Canada 506,277
Chile 63,447
United Kingdom 195,978
West Germany 226,888
Other Countries 281.518
Total 1,274,108
6638206 Asbestos clutch facings, NEC, including linings
Canada 160,905
Other Countries 163.144
Total 324,049
6638215 Asbestos brake linings for automotive use
1 Canada 5,726,553 4,681,018
Guatemala 55,287 95,364
Ecuador 76,894 114,637
Chile 26,188 63,495
Belgium 83,388 133,965
Greece 426,808 177,068
Lebanon 146,100 165,735
Iran 164,803 156,894
Singapore 133,140 82,093
Indonesia 118,415 73,897
Other Countries 700.518 869.554
Total 7,658,094 6,613,702
6638225 Asbestos brake linings, NEC
6 Canada
Mexico
Brazil
The Netherlands
Japan
Australia
Other Countries
Total
1,487,000
274,572
20,913
26,700
15,909
48,975
180,307
2,054,376
1,594,737
173,896
148,892
271,849
64,690
136,347
369,465
2,759,876
U. S. Bureau of the Census, 1975b
40
-------
4.3 Imports
Table 4.5 below lists the American imports of asbestos (unmanufactured)
from 1965 to 1975.
Table 4.5. U.S. Imports of Asbestos (Unmanufactured) for 1965 - 1976
(Clifton, 1977; U.S. Bureau of the Census, 1975 a)
Year Asbestos Import in Thousands of Short Tons
1976 658
1975 539
1974 766
1973 792
1972 736
1971 682
1970 649
1969 695
1968 737
1967 646
1966 720
1965 719
In 1975, 539,000 short tons of asbestos were imported into the U.S.,
as compared to 766,000 short tons in 1974. The decrease from 1974 to 1975 was
due to a shortage of asbestos in the Canadian supply caused by: 1) a destruc-
tive fire at Thetfor.i l-'ines, Quebec, 2) a landslide at Johns-Manville' s Jeffrey
Mine, Quebec, and 3) the 7-nionth-long strike of Quebec asbestos workers (Asbestos
Magazine, December, 1975). During 1976, 658,000 short tons of asbestos were
t-nported, a rate which is approximately midway between the 1974 and 1975 figures.
41
-------
Tables 4.6a and 4.6b list U.S. imports, by country, of unmanufactured
asbestos in 1975 and the first-half of 1976, respectively. Table 4.7 gives
<
similar data for 1973 - 1974. Table 4.8 lists U.S. imports, by country, of
manufactured asbestos products in 1975. A historical breakdown for asbestos
imports of chrysotile, crocidolite, and amoslte is Included in Table 4.9,
Asbestos Supply-Demand Relationships.
During the entire history of the asbestos industry in the U.S.,
domestic sources have been able to meet only a small percentage of U.S. require-
ments. Canada furnished 96% of all the asbestos tonnage imported by the U.S.
(1969 - 1973), but only a small portion (3%) was spinning grade fibers. The
comparatively small tonnages imported from Africa are more Important than would
appear on a tonnage basis because they consist largely of special kinds and
qualities unobtainable elsewhere (Clifton, 1975).
4.4 Supply-Demand-Use
Table 4.9 gives the asbestos supply-demand relationships for
1967 - 1976. The U.S. supply is a combination of Imports, domestic mine pro-
duction, Industry stockpiles, and governmental stockpile releases. The U.S.
supply Is distributed among Industry and governmental stockpile acquisitions,
exports, and Industry demand. The relative Importance of each is apparent from
Table 4.9. The asbestos distribution by end use, grade, and type for 1976 is
shown In Table 4.10. The major buyers of asbestos and asbestos ore are listed
in Table 4.11.
4.5 Asbestos Fiber Prices
Asbestos prices are characterized by an erratic price history. Prices
for Canadian asbestos increased about 8% in 1973, 39% in 1974, and 23% in 1975.
42
-------
Table 4.6*. U.S. Imports—by Country--of Unmanufactured Asbestos in 1975
2764010
Rap SAP
Total
2764020
Motambq
Rap SAP
Total
2764030
Canada
U King
Belgium
USSR
Rap SAP
Svaflnd
Rhodaaia
Total
2764040
Canada
Rap SAP
Rhodaaia
Total
Net
Quantity
Short Tone
Value (dollara)**
Cuatoma
P. a. a.
C.i.f.
Aabeatoa, Amoaita
3,894
3,894
1,539,951
1,539,951
1,542,143
1,542,143
1,872,035
1,872,035
Aabeatoa, Crocidolite, Blue
118
11,570
11,688
16,090
4,942,886
4,958,976
16,090
4,942,181
4,958,271
29,033
6,100,733
6,129,766
Aebeetoa, Chryaotile Crudea
71
277
22
4,523
940
2,756
1,633
10,244
9,045
82,982
2,670
920,772
663,658
952,544
1,521,421
4,153,092
9,654
82,982
2,670
920,772
663,658
952,544
1,520,611
4.152,891
9,654
121,299
4,408
1,617,748
760,556
1,291,259
1,753,361
5,558,283
Aabeatoa, Chryaotile, Except Crudea and Spinning Plbara
7,637
115
382
8,134
5,772,397
99,572
368,845
6,240,814
5,879,920
99,572
368,845
6,348,337
5,893,666
109,296
414,831
6,417,793
2764030 Aabaatoa, Chryaotile, Excapt Crudaa and Spinning Pibera
Canada
Mexico
U King
USSR
Italy
Gaza St
Rap SAP
Rhodaaia
Total
490,615
73
58
86
44
152
220
32
491,280
91,014,320
14,876
11,396
38,640
12,540
25,914
68,025
22,871
91,208,582
2764060 Aabaatoa, Unmanufactured,
Canada
Finland
Belgium
USSR
Italy
Rap SAP
Rhodaaia
Total
5,222
329
48
5,768
153
1,237
576
13,333
776,931
32,841
4,599
1,321,982
23,868
391,099
357,486
2,908,806
96,411,691
14,876
11,890
39,805
12,540
25,914
68,276
22,871
96,607,863
Crudee, Pibera,
838,340
32,298
4,599
1,321,982
23,868
424,487
357,486
3,023,060
96,526,478
14,876
11,890
40,214
16,461
25,914
95,123
27,614
96,738,570
Stucco, Etc., NES
859.639
51,915
7,426
1,822,332
38,805
533,022
473,331
3,786,470
*Sourca: U.S. Bureau of the Canaua, 197Sa
**Cuatoua Valuat Value of inporta appraiaed by U.S. Cuatoma Service.
P. a. a. Value: Tranaaetlon value of importa at foreign port of exportation.
C.i.f. Valuat Value of importa at the firat port of entry in U.S.
43
-------
Table 4.6b.
U.S. Imports—by Country—of Unmanufactured Asbestos,
January to June, 1976*
2764010
Rep SAF
Oth Cty
Total
2764020
Rep SAF
Total
2764030
Canada
Mexico
U King
Rep SAF
Rhodesia
Total
2764040
Canada
Total
2764050
Canada
Fr Germ
Rep SAF
Oth Cty
Total
2764060
Canada
Fr. Germ
USSR
Rep SAF
Oth Cty
Total
Net
Quantity
Short Tons
Customs
Value (dollars)
F.a.s.
C.i.f.
Asbestos, Amosite
1,151
20
1,171
503,663
469
504,132
509,697
669
510,366
642,607
669
643,276
Asbestos, Crocidolite, Blue
4,712
4,712
2,315,466
2,315,466
2,388,971
2,388,971
2,606,013
2,606,013
Asbestos, Chrysotile Crudes
289
234
119
351
1,095
2,088
125,175
125,486
55,992
193,918
1,115,230
1,615,801
129,108
126,948
55,992
193,913
1,115,230
1,621,196
129,108
126,948
64,090
220,191
1,200,965
1,741,302
Asbestos, Chrysotile Spinning Fibers
2,394
2,394
2,053,568
2,053,568
Asbestos, Chrysotile, Except
298,988
1,086
396
17
300, 487
60,006,713
202,826
217,440
3,919
60,430,898
2,110,240
2,110,240
2,111,611
2,111,611
Crudes and Spinning Fibers
63,427,681
202,826
219,660
3,919
63,854,086
63,598,407
257,094
235,599
3,919
64,095,019
Asbestos, Unmanufactured, Crudes, Fibers, Stucco, Etc., NES
8,759
823
6,700
1,953
54
18,289
1,450,342
179,840
1,292,721
898,889
21,969
3,843,761
1,571,118
179,840
1,293,001
920,675
22,029
3,986,663
1,572,326
320,577
2,079,238
981,292
22,368
4,975,801
*Source: U.S. Bureau of the Census, 1976;i
44
-------
Table 4.7. U.S. Imports for Consumption of Asbestos (Unmanufactured)
by Class and Country (Clifton, 1974)
Crude (includ-
ing blue fiber)
Year and country Quantity
(short
tons)
1978
Canada
Finland
Germany, West ...
Guyana " ,.
Italy
Malagasy. Republic . —
Mexico
Moaambloue
Panama . ... 1Jt_,
Portugal -„ ..—___.
Rhodesia. Southern .
South Africa.
Republic of ...
Swasiland
Yemen .
Yugoslavia . - .
1,991
79
51
846
21.629
200
Tortile fiber All other
Value Quantity Value Quantity Value
(thou- (short (thou- (short (thou-
sands) tons) sands) tons) sands)
8897
21
27
428
4.510
122
15.666 86.020 746.988 186,449
1.027 98
8
180
808
I" 8
48
rr 12
i
1 8.427
78
50
8
8
1
7
1
11
(»)
788
11
8
Total
Quantity Value
(•bo rt (thou-
tons) sands)
764.644
1.027
79
808
8
8
48
66
12
846
25.064
880
50
8
892.866
98
21
8
8
7
28
11
(»)
428
5.244
196
11
Total ............ 24.795 5.600 16.808 6.094 751.876 87.820 792,478 98.914
1974
Braxil
Canada ----
Finland ----
Germany, West
Italy
Mexico .. .
Portugal ...
Rhodesia
South Africa.
Republic of
Swasiland
UJJS.R .....
_.
115
..
99
„
18
..
85
....
26.768 10.416
._ ..
....
1 4
20 2
712.228 106.085
567 74
...
— 1.717 1.010
20.807 6.167
480 861
4
66
..
56
4
2
16 8.291
..
461
..
11
2
610
..
128
20 2
789.111 118.614
557 74
100 86
14
65 U
4 I
1.721 1.01*
28,664 6.688
480 861
461 128
Total ............ 22,718 6.676 26,889 1M88 716,607 106.808 766.164 128.822
than tt unit.
45
-------
Table 4.8. U.S. Imports—by Country—of Manufactured Asbestos Products in 1975*
Net
Quantity
Pounds
6618340 Asbestos &
Canada
Mexico
Guatmal
Colomb
U King
Belgium
W Germ
Japan
Austral
Total
12,176,880
282,803
532,566
15,259,038
9,246
7,395,456
4,149,943
145,941
246,333
40,198,206
Customs
Value (dollars)
F.a.s.
C.i.f.
Hydraulic Cement Articles NES
1,700,400
73,555
43,941
1,494,207
5,350
1,858,386
377,706
30,725
56,234
5,640,504
1,773,749
73,564
43,941
1,494,215
5,368
1,858,022
377,705
30,725
59,555
5,716,844
1,773,779
73,564
60,097
1,760,082
5,995
2,168,971
564,244
36,848
70,473
6,514,053
6638000 Asbestos Articles, NES, and Asbestos Yarn, Sliver,
Canada
Mexico
Venez
Brazil
Sweden
Norway
Finland
Denmark
U King
Nethlds
Belgium
France
W Germ
Switzld
Spain
Italy
Yugoslv
Greece
India
Phil R
Kor Rep
China T
Japan
Rep SAF
Total
Rope, Etc.,
With or Without Wire
3,988,524
2,624,027
40..381
841,938
128,742
6,369
8,499
12,780
4,373,180
11,139
32,774
137,475
1,282,955
6,187
495,545
156,022
17,664
1,140
5,261
1,000
257,256
1,094,659
1,149,464
119,527
16,792,508
4,010,223
2,478,821
40,381
831,938
128,721
6,369
8,499
12,189
4,380,595
11,139
32,795
137,897
1,278,071
6,187
495,545
156,022
17,664
1,140
5,261
1,000
244,970
1,075,207
1,135,904
119,527
16,616,065
4,019,687
2,617,067
42,674
872,701
142,887
7,749
9,149
12,594
4,794,464
11,578
35,867
147,444
1,346,141
7,168
531,694
172,358
19,251
1,226
5,919
1,555
255,633
1,154,996
1,228,451
120,127
17,558,380
*Source: U.S. Bureau of the Census, 1975a
46
-------
Table 4.9. Asbestos Supply-demand Ralationships, 1967-76
(Thousand short tons) (Clifton, 1977)
Wortd mint produelon:
UntadSlalaa
Itostol world
ToUl .'
Components of US. supply:
Domestic mine*
Shipments ol Government stockpile
eicette*
Imports, chrysoMe
Imports, amosH*
Industry stocks. Jan. 1
Total US. Mpply
CHstrtbutlon of U.S. supply:
QovsnvTwrfl •cqumbon
Industry ttocfc, Dec. 31
Exports
Industry demand
U.S. demand pattern:
Asbasioa cement pipe
Rcolng product*
Friction product!
Asbestos oniMnt sheet
Parking and g«kMi
Insulation
Paper product!
Texlles
Omer • ,
1967
123
3.084
3.207
123
1
61 S
IS
13
19
769
1
20
47
721
179
134
71
65
SI
• 22
22
14
14
145
1966
121
3,170 •
3.291
121
1
703
14
20
17
676
18
41
817
204
155
82
74
57
25
25
16
16
163
1969
126
4.042
4.168
126
S
669
11
15
IB
844
24
36
784
196
149
79
71
55
24
24
16
16
154
1970
125
3.672
3.797
125
It
626
•
14
23
806
•
7
20
47
734
184
139
73
66
51
22
22
IS
IS
147
1971
131
3.816
3.947
131
8
660
7
IS
21
842
29
54
759
191
144
76
66
S3
23
23
15
IS
151
1972
132
4.050
4.182
132
16
724
S
7
30
914
46
59
809
202
154
81
73
57
24
24
16
16
162
1973
ISO
4.448
4.596
ISO
7
771
13
8
96
1.045
103
66
676
216
166
87
79
64
26
26
16
18
174
1974
113
4.423
4,536
113 '
29
747
11
• 6
103
1.011
103
62
846
153
222
76
80
BS
29
14
63
20
94
1975
99
4.410
4.509
99
7
523
12
4
103
746
104
36
606
136
153
46
66
44
17
6
66
6
68
1976
115
•4.685
•5.000
123
2
646
10
2
104
687
115
47
725
113
140
253
64
23
20
9
31
7
65
Total U.S. demand
721
617
784
734
759
809
876
846
606
.725
•EaUfliale.
Table 4.10.
Asbestos Distribution by End Use, Grade, and Type, 1976
(Short tons) (Clifton, 1977)
.Chrysolite
Asbestos cement pip*
Asbestos c*m*ni anaM
Flooring product*
Roofing product*
Picking and giiket*
Insulation, therms)
InsUabon, electrical ..
Friction products
Coalings sod compound*
Pinnies
TMUN
Paper
Omar
Sdi "'
. . 600
1.000
1.500 1.100
1,600
100
2.600
200
200 6.900
100
300
Or 4
86.300
2.100
5.900
800
i£oo
300
2.800
300
1.600
800
Or S
26.600
3.600
6400
400
"8,300
200
too
21.100
300
100
3.300
2.500
Gr.6
3.100
9.800
600
1.900
700
1.900
200
6.800
100
1.200
22.200
4.400
Total
Or. 7 Or. 8 Chryso-
200
5.900
104.000
251.300
3400
3.600
1.900
31.000
19200
15.400
3,500
14.700
. . 116.600
22.400
. . 113.500
. . 253.600
. . 20.000
6.500
2.300
200 63.400
19.900
19.700
7.400
30.700
22.700
Croctd-
ottc
20400
100
700
300
Amotrt*
2.900
200
'l"66
'ICO
....
rido
Antho-
piiylil*
"too
•306
1.100
....
Total
asbestos
140.000
22.700
113.500
253.600
20.100
6.600
2400
63400
19.900
21.500
7.400
31.000
23.900
Total 1.700 14.900 102.400 72,800 52.900 454.000 200 698.900 21.400 4.500 1.500 726300
47
-------
Table 4.11. Buyers of Asbestos and Asbestos Ore (Compiled from data furnished by
U.S. Bureau of Mines, Washington, D.C.)*
Armstrong Cork Co., West Liberty & Charlotte St., Lancaster, Pa. 17604
Asbestos Textile Co., 165 West Wacker Dr., Chicago, 111. 60601
Carlisle Corp., 621 North College, Carlisle, Pa. 17013
Celotex Corporation, L'Anse, Mich. 49946
Certain-Teed Products Corp., 120 East Lancaster Ave., Ardmore, Pa. 19003
Firestone Tire & Rubber Co., 1200 Firestone Pky., Akron, Ohio 44317
Flintkote Co., The, Inc., 400 Westchester Ave., White Plains, New York 10604
Foseco, Inc., 20200 Sheldon Rd., Brook Park, Ohio 44403
GAF Corp., 140 West 51st St., New York, N.Y. 10020
Garlock Inc., 250 Main St., Palmyra, N.Y. 14522
Gatke Corp., Box 308 East Winona, Warsaw, Ind. 46580
Hooker Chemical Corp., Kenton, Ohio 43326
International Vermiculite Co., Girard, 111. 62640
«* Johns-Manville Corp., Greenwood Plaza, Denver, Colo. 80217
00 Mead Corp., 118 West First St., Dayton, Ohio 45402
Minnesota Mining & Mfg. Co., 3M Center, St. Paul, Minn. 55101
National Gypsum Co., Inc., 325 Delaware Ave., Buffalo, N.Y. 14202
Owens-Corning Fiberglass Co., Berlin, N.J. 08009
Pittsburgh Corning Corp., No. 1 Gateway Center, Pittsburgh, Pa. 15207
H.K. Porter Co., Inc., 601 Grant St., Pittsburgh, Pa. 15219
Raybestos Manhattan, Inc., Bridgeport, Conn. 06601
Rogers Corp., Rogers, Conn. 06263
Standee Brake Lining Co., 2701 Clinton Dr., P.O. Box 93, Houston, Tex. 77020
U.S. Gypsum Co., 101 South Wacker, Chicago, 111. 60606
U.S. Plywood Corp., South River, N.J. 08882
*
List not considered complete.
-------
Table 4.12 lists the average annual asbestos price from 1956 to 1976 and com-
pares it to a figure based on constant 1975 dollars. Table 4.13 lists recent
prices for various grades and origins of asbestos. Iht remarkable disparity of
grade prices is evident from Quebec chrysotile fiber prices. Grade No. 7 (shorts)
was priced at $89 per ton, while Grade No. 1 (crudes) cos.: $3496 per ton.
4.6 Future Outlook
Projections for future use of asbestos are reported by Clifton (1977).
The information and projections contained in this subsection come directly from
Clifton (1977).
The domestic demand for asbestos is expected to increase at a slow
rate; the low rate of annual growth is expected to be 1.0%, while the high rate
is expecte tc be 3.8%. .The U.S. demand for asbestos in the year 2000 is pro-
jected to be about 1.3 times that the 20 year trend point for 1975. Projection
trends for th U.S. demand are illustrated in Figure 4.2. The forecast for U.S.
demand of asbestos by end use is given in Table 4.14.
1.000
100
100
700
eoo
1,042,
10-YEAR TREND
TREND
19SS IMS 1»7I IMS IMS 2000
Figure 4.2. U.S. Asbestos Demand and Projected Trends to 2000 (thousand short
tons) (Clifton, 1977)
49
-------
Table 4.12. Time-Price Relationship for Asbestos (Clifton, 1977)
Average Annual Price, Dollars Per Short Ton
Year
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
Actual Price
89.78
88.09
90.50
91.17
94.62
95.60
94.85
92.44
98.70
97.92
100.63
101.91
98.93
110.03
115.64
117.54
116.63
122.22
122.27
144.14
206.31
Constant 1975
Dollars
181.63
172.38
174.34
171.83
175.35
175.61
171.09
164.31
172.73
167.67
166.82
164.11
152.46
161.46
161.06
155.76
148.42
147.01
133.65
144.14
197.56
50
-------
Table 4.13. 1975 Prices of Various Asbestoses
(Asbestos Magazine, December, 1975)
ARIZONA Pei Ton at 2000 Lt>s.. F.OB GtoM. Arizona
As ol April 17. 1975 U.S. Dollars
No 1 Crude (Soft) S $2000.00
No. 2 Crude (Soft) 150000
AAA . . . . . 110000
Group No. 3—Nonferrous Filtering—Plastic 715.00— 80000
Group No. 4—Nonterrous Filtering—Plastic 700.00— 800 00
Group No 7—White Shorts 10000— 20000
QUEBEC Per Ton ol 2000 UK., f OB. Mine
As of December 1. 1975 Canadian Dollars
No 1-Crude S . $349600
No. 2—Crude . . 189900
No 3—Spinning Fiber 891.00— 1463.00
No 4 -Asbestos Cement Fiber 492.00— 82900
No. 5—Paper Fiber 278 00— 392 00
No 6—Paper and Shingle Fiber 236.00— 24400
No. 7—Shorts 8900— 19800
CASSIAR Per Ton ot 2000 Lbs . FOB. North Vancouver. B.C
As ol August 1. 1975 Canadian Dollars
Cassiar Mine
C-i $2916.00
AAA Grade—Nonferrous Spinning Fiber/Canadian Group 3 1685.00
AA Grade—Nonferrous Spinning Fiber/Canadian Group 3 1340 00
A Grade—Nonferrous Spinning Fiber/Canadian Group 3 1020 00
AC Grade—Nonferrous Spinning Fiber/Canadian Group 3 735.00
AK Grade—Asbestos Cement Fiber/Canadian Group 4 524 00
AS Grade—Asbestos Cement Fiber/Canadian Group 4 454 00
AX Grade—Asbestos Cement Fiber/Canadian Group 5 41600
AY Grace—Asbestos Cement Fiber/Canadian Group 5 .29200
AZ Grade—Asbestos Cement Fiber/Canadian Group 6 216 00
Clinton Mine
CP Grade—Asbestos Cement Fiber/Canadian Group 4 492.00
CT Grade—Asbestos Cement Fiber/Canadian Group 4 445.00
CY Grade—Asbestos Cement Fiber/Canadian Group 5 292.00
CZ Grade—Asbestos Cement Fiber/Canadian Group 6 216 00
VERMONT Per Ton ot 2000 Los., F.O.B. Morrisvilre. Vermont
As of January 1. 1976 U.S. Dollars
Grade 4T—Fiber $ —$ 418 00
Grades 50 thru 5R—Fiber 27500— 324.00
Grade 60—Waste . . .— 200 00
Grades 70 thru H—Shorts 8300- 16000
Grade 7TF—Floats (Shorts) . — 72.00
Grade 8S—Shorts — 54 00
Hooker No. 1—in 50-lb woven poly bags/eft 12/1/75 970.00
Hooker NO 2—in 100-lb woven poiy bags/eft 12/1/75 485 00
51
-------
Table 4.14.
Projections and Forecasts for U.S. Asbestos Demand By End Use,
1975 and 2000 (Thousand Short Tons) (Clifton, 1977)
2000
End Use
1975
Contingency Forecasts for United States
Total
Forecast Range
Forecast
Base
Low
High
Probable
Asbestos cement pipe
Asbestos cement sheet
Flooring products
Roofing products
Packing and gaskets
Friction products
Insulation
Paper
Textiles
Other
153
44
136
46
17
66
6
66
6
68
244
95
323
128
38
124
39
28
29
256
270
115
187
92
35
97
17
76
24
113
527
224
364
180
68
189
33
149
47
219
274
116
189
93
35
98
17
77
24
115
608
1,026
2,000 1,038
The forecast base for friction products is derived from statistical analysis
on data for 1960-75. All other 2000 forecast base figures are based on data
for 1960-73.
52
-------
5.0 MINING AND MILLING
5.1 U.S. Mines and Mills
Although mineral deposits which sometimes contain asbestos are
located throughout the United States (Figure 5.1), asbestos is mined in only a
few states. The map in Figure 5.2 designates the location of mines which are
operating or which have been closed recently. In order of decreasing annual
production, the mining states are California, Vermont, Arizona, and
North Carolina. Table 5.1 lists the American mines which are operating or
have recently closed, along with the associated mills. All of the mines
produce chrysotile asbestos with the exception of the Powhattan mine in North
Carolina which produced anthophyllite asbestos.
The largest mines are the Vermont Asbestos Group mine (formerly
owned by GAF Corp.) in Vermont and the Calaveras Asbestos Ltd. mine (formerly
controlled by H.K. Porter Co.) in Copperopolis, California (Asbestos Magazine,
December, 1975). The inactive Coalinga Asbestos Co. mine (Johns-Manville) was
the second largest mine in California and the third largest nationally. En-
vironmental regulations are cited as the prime reasons for the closing of the
Johns-Manville mine (Clifton, 1976; Harwood and Blasznak, 1974; Asbestos
Magazine, December, 1974, 1975). The Powhattan mine in North Carolina was re-
ported as inactive since 1973 (Harwood and Blasznak, 1974).
Potential mining has been discussed for Alamore, Texas (tremolite
asbestos), Sonora, California, and the Yukon region of Alaska (Asbestos
Magazine, December, 1972, 1974).
It should be noted that actual mining production data for each mine
cannot be accurately reported for proprietary reasons. Since California had,
53
-------
in
Areas of the U. S. wri'C* -
-------
ID
5
N
O Currmtlv Operating
A Recently Cloud
figure 5.2. Asbestos Mines in the United States
55
-------
Table 5.1. American Asbestos Mines and Mills (Harwood and Blasznak, 1974; Clifton, 1974, 1975;
Asbestos Magazine, December, 1972 - 1975) Note: All mines are open pit except
those in Arizona, which are underground.
1.
2.
3.
4.
S.
6.
7.
8.
9.
Operating Company
Atlas Asbestos Co.
Calaveras Asbestos Ltd.
Union Carbide
Coaling* Asbestos Co.,
dlv. of Johns-Hanville
Vermont Asbestos Group
Jacquays Mining Corp.
Asbestos Hfg. Co.
Metate Asbestos Co.
Povnattao Mining Corp.
Mine
Location
Fresno County,
Calif.
Calaveras County,
Calif.
San Benlto County,
Calif.
Fresno County,
Calif.
Hyde Park, Vt.
Gila County.
Arli.
Cila County,
Arlr.
Glla County,
Ariz.
Burns Ide. B.C.
Employees*
20
36
36
20
58
8
—
—
4
Mill
Location
Coalings,
Calif.
Copperopolls,
Calif.
King City,
Calif.
Coallnga,
Calif.
Hyde Park, Vt.
Globe, Arls.
Globe, Ariz.
Globe, Arlr.
<
Baltimore, Md.
Estimated
Production
Employees* (Short Tons)
SO 25.000/yr.
135 220/day
50 110/day
50 110/day
143 220/day
5 3.000/yr.
Closed
Closed
8 700/yr.**
Consents
Used in vinyl-floor tile
Used in asbestos-cement
pipes and sheets
Used in reinforcing
thermoplastics (Calidrla);
Japan is a major consumer
Closed in June, 1974
Used in heat-resistant
materials, Mostly by GAF;
purchased in 1975 from
GAF
Used for electrical and
filter media;' most la
exported to Japan
Closed
Closed
* 1973 figures (Harwood and BUsxnak. 1974)
•* Hill capacity figure
-------
until recently, several operating mines, the Bureau of Mines has reported
annual production for the state. But as a result of recent mine closings, the
annual California production report might be terminated (Clifton, 1976).
Table 5.1 contains estimates of Harwood and Blasznak (1974) for several indi-
vidual daily mine productions and the estimate of Asbestos Magazine for annual
production of two mines. Based upon the combined data of Harwood and Blasznak,
Clifton, and Asbestos Magazine, we estimate that at the present time about
55- 65% of the asbestos mined in the U.S. is mined in California, 35-45% comes
from Vermont, and less than 5% is mined in Arizona and North Carolina. Until
recent mine closings and sales altered the California production, California
had accounted for nearly 70% of the domestic fiber.
The lower limit for economical asbestos production is estimated at
4% asbestos containing ore (Berger and Oesper, 1963). Clifton (1975) evaluated
the effect-of continuous mine operations on the percent fiber recovery by a
linear regression analysis of Quebec mine data (see Figure 5.3). He forecasts
that as the age of a mine increases, the percent fiber recovery decreases.
This will result in an increasing fiber production cost until mining is no
longer profitable. By reason of analogy, the Quebec data should be generally
true for U.S. mines, especially the Vermont mine, which is an outcrop of the
Quebec deposits. Based on the above data, the Vermont mine could be close to
being mined out.
5.1.1 Ore Characteristics
The chrysotile asbestos content of ore varies between deposit
locations. The lowest concentration is deposited in the Vermont ore which
consists of less than 4% asbestos by weight, and the highest concentration is
57
-------
3
I
»
^
r»
*
<
200
Z
o
100
«A
Z
o
QUEBEC PRODUCTION TRENDS
20
10
1950 1960 1970 1980 1990
1 Ore and waste rock exclusive of overburden
2000
BUREAU OF MINES
U.S. DEPARTMENT OF THE INTERIOR
Figure 5.3. Quebec Production Trends, From Analysis of 1951 - 1970 Data
(Clifton, 1975)
58
-------
deposited in the Coalinga, California, district which is approximately 60% by
weight asbestos.
The Vermont ore deposit is an outcrop of the large Quebec
deposits in Canada. While the Vermont deposit contains some spinning grade
fibers (Harwood and Blasznak, 1974), most fiber is shorter grade and is con-
sumed in the manufacture of heat resistant products (Asbestos Magazine,
December, 1973).
The Calaveras Asbestos Ltd. mine in Copperopolis, California,
produces the normal long fibered form of chrysotile asbestos which is primarily
used in asbestos-cement products (Harwood and Blasznak, 1974; Asbestos Magazine,
December, 1975). Three mines, the Coalinga (Johns-Manville), Atlas, and Union
Carbide, are in close proximity to each other near Coalinga, California. They
work an ore body which is 10 miles long and 0.25 miles wide. The ore from
these mines is atypical of asbestos. Instead of a fibrous vein structure, the
asbestos is in a platy, slippery form known locally as desert leather (Harwood
and Blasznak, 1974). The fibers from this tract are short and therefore are
used in floor tile and reinforced thermoplastics (Asbestos Magazine, December,
1971, 1975). Arizona produces an exceptionally high quality, low iron content
asbestos, most of which is used for electrical insulation and for filtering
media (Asbestos Magazine, December 1975). Most of the Jacquay Mine production
is exported to Japan (Harwood and Blasznak, 1974).
59
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6.0 FRICTION MATERIALS
Friction materials are used in practically all industries as a key component
in clutches for transmitting torque, brakes for slowing down or stopping motion,
or as torque limiters. Although friction applications to automobile brakes and
clutches are the most important commercially, asbestos-friction applications are
not limited to brakes and clutches in automobiles, trucks, busses, construction
equipment, and railroad cars. Rather, these applications are found wherever
motion must be controlled. The following examples show the diversification of
friction material usage: farm tractors, presses, hoists, tensioning devices in
production of wire and plastic rope and cable, lift trucks, machine tools,
shuttlecars, specialized mining equipment, chainsaws, drilling equipment, spin-
ning and knitting equipment, x-ray machines, wheel brakes, tape recorders,
typewriters, bicycle brakes, snowblowers, and washing machines (Daly et al.,
1976). Asbestos is an important ingredient in these friction material products
because it imparts strength, good friction properties, can withstand high tem-
peratures, and is a good insulator.
•
6.1 Statistics
6.1.1 Use Quantity and Shipment Values
From Table 4.9 (p. 46), it can be seen that U.S. demand for
asbestos in friction products has ranged from sixty-five to eighty thousand
short tons annually from 1967 to 1976. This amounts to approximately 9% of the
total U.S. asbestos demand (consumption).
The trend in the value of shipments of asbestos friction materials
is shown in Table 6.1. During the five year period from 1967 to 1972, shipment
60
-------
Table 6.1. Value of Shipments of Asbestos Friction Materials (U.S. Bureau of the Census,
1972 Census of Manufacturers)
SIC
Product
Code
32922 —
32922 11
32922 15
32922 21
32922 51
32922 55
32922 00
Total Product Shipments,
including interplant transfers
(millions dollars)
Product
Asbestos Friction Materials - Total
Brake Linings:
Woven, containing asbestos yarn,
tape, or cloth
Molded, including all non-woven types
Disc Brake Pads
Clutch Facing:
Woven, containing asbestos yarn,
tape, or cloth
Molded, including all non-woven types
Asbestos Friction Materials, n.s.k.
1972
209.5
10.2
113.1
14.2
19.9
48.5
3.6
1967 1963
144.4 177.7
13.5
95.6
— —
17.2
16.1
2.0 —
-------
values increased by 45%, as compared to a 23% increase for the four-year period
from 1963 to 1967. Using an annual figure of 9% for shipment value increases,
the total product shipments of asbestos friction materials would be approxi-
mately $271.3 million in 1975 and $295.7 million in 1976.
Table 6.1 also gives a breakdown for the major asbestos friction
material products. In 1972, brake linings accounted for nearly 59% of shipment
values while clutch facings accounted for slightly over 32% of the shipment
values. If disc brake pads are included along with brake linings, then asbestos
brake-materials account for 65.6% of the total value of asbestos-friction
materials. Clearly then, "brakes" are by far the most important commercial
product in the friction material category.
6.1.2 Industrial Firms
Table 6.2 lists the U.S. manufacturers of asbestos-bearing
friction materials along with their respective sales of friction materials in
1975. The larger firms include not only the essentially captive producers, such
as the Delco-Moraine and Inland Divisions of General Motors Corporation and the
Cycleweld Division of Chrysler Corporation, but also the diversified industrial
product manufacturers, such as Raybestos-Manhattan, Bendix, Abex, and H.K.
Porter. In addition, the list includes many smaller, typically single-plant
firms, which manufacture friction products for both the original equipment and
replacement market.
The first eight firms listed on Table 6.2 account for nearly 75
to 85% of the total estimated sales of asbestos friction products in 1975. This
ratio is consistent with the historical pattern for the industry, which indi-
cates that in the 1954 to 1967 period, the eight largest firms accounted for
between 86 and 91% of the industry's value of shipments (Margolin and Igwe,
1975; U.S. Bureau of the Census, 1972).
62
-------
Table 6.2. U.S. Manufacturers of Asbestos-Bearing Friction Materials
(Economic Information Systems, Inc., 1976; Margolin and
Igwe, 1975; SRC Estimates)
Company
Plant Location
Estimated 1975
Sales of
Friction Materials
($ million)
Raybestos-Manhattan, Inc.
Bendix Corporation
Abex Corporation
General Motors Corp.
H.K. Porter Co.
Chrysler Corporation
Borg Warner Corporation
World Bestos Co.
National Friction
Products Corp.
Gatke Corporation
Carlisle Corporation
Maremont Corporation
Stratford, Conn.
Mannheim, Pa.
CraWfordsville, Ind.
Fullerton, Calif.
Troy, N.Y.
Cleveland, Tenn.
Cleveland, Ohio
Troy, Michigan
American Brakeblok Division
Winchester, Va.
Delco-Moraine Div.
Dayton, Ohio
Inland Division
Dayton, Ohio
Huntington, Indiana
Richmond, Ky.
Cycleweld Division
Trenton, Michigan
Spring Division
Bellwood, 111.
New Castle, Ind.
Logansport, Ind.
Warsaw, Ind.
Ridgeway, Pa.
Grizzly Products Division
Paulding, Ohio
110.0
72.5
60.1
30.0
26.0
18.8
10.2
10.0
9.7
8.7
63
-------
Table 6.2. U.S. Manufacturers of Asbestos-Bearing Friction Materials (Cont'd)
Company
Plant Location
Estimated 1975
Sales of
Friction Materials
($ million)
Scandura, Inc.
Mar Pro Corporation
Standee Industries
Forcee Mfg. Corporation
Royal Ind. Brake
Products, Inc.
Auto Friction Corp.
L.J. Miley Co.
Friction Products Co.
United States Brake
Lining Corp.
Brassbestos Mfg. Corp.
Southern Friction
Material Co.
Reddaway Mfg. Co.
Molded Ind. Friction Corp.
Auto Specialties Mfg. Co.
Lasco Brake Products Co.
California Blok Co.
M6M Brakes, Inc.
Wheeling Brake Block
Mfg. Co.
Charlotte, N.C.
Grizzly Brake Division
Chicago, 111.
Houston, Texas
Tappahannock, Va.
Danville, Ky.
Lawrence, Ma.
Chicago, 111.
Medina, Oh.
Miami, Fla.
Patterson, N.J.
Charlotte, N.C.
Newark, N.J.
Prattvilie, Ala.
St. Joseph, Mich.
Oakland, Calif.
Gardena, Calif.
Cloverdale, Calif.
Wheeling, W.Va.
Bridgeport, Ohio
8.7
5.7
5.7
5.5
4.0
2.9
1.7
1.7
64
-------
Table 6.2. U.S. Manufacturers of Asbestos-Bearing Friction Materials (Cont'd)
Company
Plant Location
Estimated 1975
Sales of
Friction Materials
($ million)
Baldwin-Ehnet Hill, Inc.
Thiokol Chemical Corp.
P.T. Brake Lining Co.
Trenton, N.J.
Trenton, N.J.
Lawrence, Mass.
Hunt/Airheart Products, Inc. Chatsvorth, Cal.
Re-Bilt Auto Products Corp. Brooklyn, N.Y.
65
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One Important discrepancy in figures should be explained. For
1972, the U.S. Bureau of the Census listed the total value of shipments of as-
bestos friction products as $209.5 million which was projected as $271.3 million
for 1975 in Section 6.1.1. From Table 6.2, the estimated sales of asbestos
friction materials in 1975 total nearly $370 million for the listed figures; the
companies with no listed figures may total another $50 million. The difference
from the value of shipments as reported by the Bureau of the Census and the
estimates given in Table 6.2 are due to variations in definition and reporting
coverage. Shipment value does not include freight charges and excise taxes
which are included in the actual sale cost. Also, the Bureau of the Census
figures are based upon surveys at 23 asbestos-friction material establishments.
Table 6.2 contains 44 establishments. Although the Bureau of the Census survey
probably includes most of the larger establishments, the ones which were not
surveyed are not available.
6.1.3 Plants
Figure 6.1 shows the geographical dispersion of friction materials
plants in the U.S. Not surprisingly, they tend to be concentrated in and around
the major metropolitan centers of the Northeast and Midwest, with a few plants
located in California to primarily cater to the needs of the automobile assembly
plants in that part of the country.
As would be expected of a mature industry, most of the plants and
equipments are old, usually over forty years of age, with the possible exception
of newer captive facilities belonging to the automobile manufacturers. Pro-
duction processes have changed only marginally over the years, and labor rather
than capital intensity appears to be the norm in most of the older plants
(Margolin and Igwe, 1975).
66
-------
Figure 6.1 Geographical Dispersion of U.S. Friction Materials Plants (Modified from Margolin and
Igwe, 1975)
-------
6.1.4 Future Projections for Asbestos Use (Clifton, 1975)
Asbestos demand for friction products was projected to the year
2000 at an annual growth rate of 1.50 percent. This figure was based on a
formula derived from least-squares regression analysis of total asbestos demand
modified by the estimated growth in the automobile industry and economic indi-
cators, which showed the best correlation.
Asbestos is an important part of many types of friction materials
for use in automobiles, trucks, and other transportation equipment. Modern
industry could scarcely function without asbestos friction materials. In addi-
tion to using asbestos in brake linings, today's motor cars, equipped with
automatic transmissions, get their drive from metal transmission disks, which
are covered with a super-tough paper containing crocidolite asbestos. The
average automobile with power shift contains from 8 to 12 of the paper lined
disks. Although the quantity of asbestos in each transmission is small, the
output of more than 8 million automatic transmissions annually requires disk
paper production in hundreds of tons.
A new composition disk-brake-shoe unit containing asbestos,
designed to meet the critical braking requirements for the new 150-mile-per-hour
passenger train systems, has been developed.
Based on an estimated forecast of the number of motor vehicles
produced in the year 2000 (approximately double 1973 production) and on the
assumption that the use of asbestos per vehicle will remain at present levels,
the forecast for asbestos demand in user-operated vehicles is projected to
118,000 tons. An increased number of public transportation vehicles and equip-
ment using parts made of asbestos or maintaining the present quantity used per
vehicle could result in a demand as high as 144,000 tons.
68
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6.2 Manufacturing Process Technology
Several different processes are used to manufacture asbestos brake
linings and clutch facings. Manufacture can be accomplished by a molding proc-
ess, in a dry or wet-mixed state, or by a woven process; these processes, which
are described below, are taken from Gregg (1974). The raw materials used for
forming asbestos-friction materials are discussed in Section 6.3.
6.2.1 Molded Products
6.2.1.1 Dry-Mix Process
The manufacturing steps typically used in dry-mix molded
brake lining manufacture are shown in Figure 6.2. The bonding agents, metallic
constituents, asbestos fibers, and additives are weighed and mixed in a two-
stage mixer. The mix is then hand-tamped into a metal mold. The mold is placed
in a preforming press which partially cures the molded asbestos sheet. The
asbestos sheet is taken from the preforming press and put in a steam preheating
mold to soften the resin in the molded sheet. The molded sheet is formed to the
proper arc by a steam-heated arc former, which resets the resin. The arc-formed
sheets are then cut to the proper size. The lining is then baked in compression
molds to retain the arc shape and convert the resin to a thermoset or permanent
condition. The lining is then finished and, after inspection, is packaged. The
finishing steps include sanding and grinding of both sides to correct the thick-
ness, edge grinding, and drilling of holes for rivets. Following drilling, the
lining is vacuum-cleaned, inspected, branded, and packaged (Gregg, 1974).
6.2.1.2 Wet-Mix Process
Figure 6.3 shows the major steps in the manufacture of wet-
mixed molded brake linings. The name "wet mix" process is a misnomer and refers
69
-------
RAW MATERIAL*
STORAGE
PROPORTIONING
COOLING WATER 8
PREFORMING
PRESS
TEAM
++
PREHEAT
COOLING WATER STEAM
COOLING WATER
^COMPENSATE
COMPRESSION MOLD
BAKING OVEN
FINISHING
INSPECTION
PACKAGING
STORAGE
1
CONSUMER
Figure 6.2. Dry-Mixed Brake Lining Manufacturing Operations
(Gregg, 1974)
70
-------
to the use of a solvent. The ingredients of the molded lining are actually
relatively dry. After weighing, they are mixed in a sigma blade mixer. The
mixed ingredients are then sent to grinding screens where the particle size of
the mixture is corrected. The mixture is conveyed to a hopper and is forced
from the hopper into the nip of two form rollers which compress the mixture into
a continuous strip of friction material. The strip is cut into the proper
lengths and then arc-formed on a round press bar. The cutting and arc forming
operations are done by separate units. The linings are then placed in racks and
either air-dried or oven-dried to remove the solvent. An alternative process is
to place the arc-formed linings in metal molds for baking in an oven. From the
ovens, the linings are finished, inspected, and packaged (Gregg, 1974).
Molded clutch facings are produced in a manner similar to
the wet-mixed process. The rubber friction compound, solvent, and asbestos
fibers are introduced into a mixer churn. After the churn mixes the ingredi-
ents, the mixture is conveyed to a sheeter mill which forms a sheet or slab of
the materials. The sheet is then diced into small pieces by a rotary cutter.
The pieces are placed in an extrusion machine which forms sheets of the diced
material. The sheets are cut into the proper size and then punch-pressed into
doughnut-shaped sheets. The scraps from the punch press are returned to the
extrusion machine. The punched sheets are placed on racks and sent to a drying
oven and then a baking oven for final curing and solvent evaporation. The oven-
dried sheets are finally sent to the finishing operations. Figure 6.4 illu-
strates the steps in the manufacture of molded clutch facings (Gregg, 1974).
6.2.2 Woven Products
Woven clutch facings and brake linings are manufactured of high
strength asbestos fabric that is frequently reinforced with wire. The fabric is
71
-------
RAW MATERIALS
STORAGE
PROPORTION***
MIXING
GRINDING
SCREENS
TWO-ROLL
FORMNQ
ARC FORMING
AIR DRYING
DRYING OVEN
SOLVENT
SOLVENT
A
FINISHING L«»«fe> DUST
INSPECTION
PACKAGING
STORAGE
CONSUMER
Figure 6.3.
Wet-Mixed Molded Brake Lining Manufacturing Operations
(Gregg, 1974)
72
-------
COOLING WATER
RAW MATERIALS
STORAGE
PROPORTIONING
STEAM
TWO-ROLL FORMING
(SHEETER MILL)
COOLING WATER
CONDENSATE
[ROTARY CUTTER |
[EXTRUSION MACHINE]
I CUTTINQI
(RECYCLED SOUD8)
I PUNCH PRESS H••
SOLVENT
[DRYING OVEN|
c ^
SOLVENT
OUST
INSPECTION
PACKAGING
STORAGE
CONOUMCR
Figure 6.4. Molded Clutch Facings Manufacturing Operations
(Gregg, 1974)
73
-------
predried in an oven or by an autoclave to prepare it to be impregnated with
resin. The fabric can be impregnated with resin by several techniques: 1) immer-
sion in a bath of resin, 2) introducing the binder in an autoclave under pressure,
3) introducing dry impregnating material into carded fiber before producing
yarn, and 4) imparting binder into the fabric from the surface of a roll. After
the solvents are evaporated from the fabric, it is made into brake linings or
clutch facings. Brake linings are made by calendering or hot pressing the
fabric in molds. The linings are then cut, rough ground, placed in molds, and
placed in a baking oven for final curing. Following curing, the lining is
finished, inspected, and packaged (Gregg, 1974).
Figure 6.5 illustrates the manufacture of woven clutch facings.
The treated fabric is cut into tape-width strips by a slitting machine. The
strips are wound around a mandrel to form a roll of the fabric. The roll is
i
pressed in a steam-heated press and then baked in an oven to cure the resin in
the clutch facing. Following curing, the clutch facing is finished, inspected,
and packaged (Gregg, 1974).
6.3 Composition of Friction Materials
i
Many raw materials, including some whose exact roles are regarded as
proprietary knowledge, are used in varying quantities in the manufacutre of
friction materials. The major, or foundation constituent, of practically all
organic friction materials is asbestos fiber. The asbestos usually used in
friction materials is chrysotile from Quebec or Vermont (Jacko and DuCharme,
1973); grades 3-7 are used; however, grades 5 and 7 account for nearly 82% of
the total (Clifton, 1977). Asbestos is used because of its thermal stability,
relatively high friction level, and reinforcing properties.
74
-------
I TREATED FABRIC |
| SLITTING |
PREFORM
WINDING
COOLING WATER 8TEA
I BAKING OVEN j
FINISHING
INSPECTION
PACKAGING
STORAGE .
COOLING WA1CM
OUST
CONSUMER
Figure 6.5. Woven Clutch Facings Manufacturing Operations
(Gregg, 1974;
75
-------
Asbestos alone does not offer all of the desired friction properties.
Therefore, other materials, known as property modifiers, are added to the asbes-
tos fibers. Modifiers are varied in type and content to provide desired levels
of effectiveness, wear, fade, recovery, and noise. A binder is also added to
hold the other materials together with adequate strength.
6.3.1 Binders
Table 6.3 lists binders and property modifiers which are used in
automotive brake linings. The binders used in the automotive industry today are
primarily phenolic-type resins which are noted for high binding efficiency and
ability to withstand pyrolytic breakdown (Rohl £t_ al., 1976). They are prepared
as the condensation product between the appropriate phenol (sometimes modified)
and formaldehyde in the presence of an acidic catalyst to yield the novolak.
When mixed with an appropriate curing agent, they polymerize at elevated tem-
peratures to an insoluble, infusible mass (Jacko and DuCharme, 1973). Other
resin systems in wide use are based on elastomers, drying oils, or combinations.
6.3'.2 Property Modifiers
Perhaps the widest range of materials used in friction products
are the property modifiers. Table 6.3 indicates the range and diversity of
these modifiers. In general, property modifiers can be divided into two classes:
non-abrasive modifiers and abrasive modifiers (Jacko and DuCharme, 1973).
6.3.2.1 Non-Abrasive Modifiers
Non-abrasive friction modifiers can be classified further as
low friction and high friction. The most common and best known of the high
friction materials is known as friction dust. This is a cured resinous materi-
al. The most frequently used variety is derived from cured or polymerized
76
-------
Table 6.3. Binders and Property Modifiers In Automotive Brake Linings
(Rohl et al., 1976; Jacko and DuCharme, 1973; various patent
literature; Bark e£ al., 1975)
Binders
Phenolic-type resins
Natural rubber
Buna N rubber
Nitrile rubber
Tire scrap
Pitch
Cork
Gilsonite
Elastomers
Drying oils
Property Modifiers
Graphite
Coke
Coal
Carbon black
Gilsonite
Rottenstone (SiCO
Quartz (SiCO
Wollastonite (CaSiCL)
Brass Chips
Zinc and compounds
Alluminum
Limestone (CaCO,)
Clays
Silicas
Barite
Lead and compounds
Friction dusts
Antimony compounds
Calcium compounds
Copper and compounds
Barium hydroxide
Potassium dichromate
Magnesium carbonate
Iron oxide
Cryolite
Fluorspar
Cardolite
Nickel
Sulfur
Use Function
Lower friction coefficient and noise
Remove decomposition deposits
it
it
it
it
Improve wear resistance
it
it
Lubricant to prevent grabbing
See discussion in Section 6.3.2.1
Not available
it
it
it
n
Molybdenum disulfide
Calcium fluoride
Lubricant
Lubricant
77
-------
cashew-nut-shell liquid, chemically a phenolic compound. When heated with
hardening agents, such as hexamethylenetetramine or formaldehyde, it becomes
sufficiently hard or polymerized to be granulated. Many other cured resinous or
polymeric materials, some with fillers, are also used. Certain friction dusts
are combinations of these materials and cashew resin. Ground rubber is normally
used in particle sizes similar to, or slightly coarser than, those of the cashew
friction dusts for noise, wear, and abrasion control (Jacko and DuChanne, 1973).
Carbon black, graphite, petroleum coke flour, or other
carbonaceous materials may also be added as friction modifiers to lower the
friction coefficient or to reduce noise. These materials are normally used in
the form of fine powders or particles, although graphite is sometimes used in
coarse particles or pellets. The amount of friction modifier added is dependent
upon the properties desired in the final composite (Jacko and DuCharme, 1973).
6.3.2.2 Abrasive Modifiers
Abrasive modifiers, such as alumina and the silicas, are
usually used in relatively small amounts and only in very fine particle sizes
(generally 100 mesh or finer). Particle size is limited by the fact that large
particles of such hard materials would groove and wear the mating surfaces.
Minerals are generally added to improve wear resistance at minimum cost. Those
most commonly used are ground limestone (whiting) and barytes (barium sulphate),
though various types of clay, finely divided silicas, and other inexpensive or
abundant inorganic powders may also perform this function. Such materials are
inorganic in nature and tend to detract from noise properties and mating surface
compatibility (Jacko and DuCharme, 1973).
Metals or metal oxides may also be added to perform specific
functions. Brass chips are frequently found in heavy-duty friction materials
78
-------
where, as scavengers, they break up undesirable surface films. Zinc and alumi-
num are also used. Zinc chips, in relatively small amounts, can contribute
significantly to recovery of normal performance following fade (Jacko and
DuCharme, 1973).
6.3.3 Composition
The average composition of a typical automobile and truck brake
lining is shown in Table 6.4a. Individual mixes may vary considerably from these
averages.
Table 6.4a. Average Brake Lining Composition (Lunch, 1968)
(wt %)
Ingredient
Asbestos
Resins and Polymers
Oxides and Pigments
Metals
Carbon, Graphite, etc.
Automobile
55
28
9
3
5
100%
Truck
33
48
16
2
1
100%
Manufacturers are very reluctant to release their exact composi-
tions due to proprietary considerations. A search of patent literature reveals
limited information, although several examples from the patent literature are
given in Table 6.4b.
6.3.4 Summary
The tables and examples given in Section 6.3 have been included
to illustrate the wide variety of compositions which are possible for fabrica-
tion of automotive and truck brake linings. Brake linings have been singled out
79
-------
Table 6.4b. Brake Lining Compositions from Patent Literature
(wt %)
Example No. 1*
Asbestos
Barite
Phenolic resin binder
Brass
Magnesium carbonate
Limestone
Organic calcium powder
55
10
20
5
8
8
10
Example No. 2**
Asbestos
Phenolic resin
Nitrile rubber
Cashew dusts
Calcium fluoride
Copper iodide
60
15
3
12
7
3
Example No. 3***
Asbestos
Barite
Graphite
Brass
Phenolic resin
Lead oxide
Buna N rubber
Naphtha
Copper sulfide
Methyl ethyl ketone
35
2.5
7
13
7
11.5
8
7
12.5
4
Example No. 4****
Asbestos
Tarry residue
Barite
Phenolic resin
Graphite
50
12
20
20
2
* Sakata e£ al., 1974 (Hitachi)
** Toyota Central Research and Development Labs, 1971
*** Keller, 1969 (Abex)
**** Mitchell, 1974 (duPont)
80
-------
from the asbestos-friction products for examination because of their dominance
of the asbestos-friction products market as shown in Table 6.1. When the varia-
tions of compositions are coupled with the variations of manufacturing process
methods (as described in Section 6.2), it is possible to view a brake lining
made by company A as substantially different from a brake lining made by com-
pany B, although the intended use applications may be the same. From this
standpoint, it is entirely reasonable to speculate that asbestos emissions
during automotive brake use may vary in concentration, depending upon composi-
tion and process manufacture of the individual linings.
6.4 Asbestos Emissions from Brake Lining Use
Asbestos has been identified in over 200 air samples taken from the
atmosphere of 49 cities in the United States (Nicholson et al., 1973); asbestos
was present in every sample taken. Asbestos has also been found in air samples
from European cities (Holt and Young, 1973) and from air samples collected in
Australia (Alste et al., 1976). The asbestos manufacturing industry may not be
the source of the asbestos emissions found in urban air samples cited above.
According to Holt and Young (1973), "the object of our investigations was only
to determine whether asbestos fibres are present in the atmosphere of towns
where there is no asbestos industry. The result was positive in every case."
The source of asbestos emissions, in the absence of asbestos mining
and industry, is a matter of speculation. Holt and Young (1973) and
Selikoff et al. (1972) suggest that the asbestos source may be construction
which uses building materials made from asbestos. Alste eit al. (1976) consider,
as a source, that asbestos emitted from automobile brake linings is a "strong
possibility." Alste et al^. (1976) found that the air concentration of asbestos
81
-------
was much higher at points where considerable braking occurred, as compared to
points of virtually no braking. This result is apparently in agreement with
measurements made in New York City which found that the asbestos air concen-
trations contiguous to a toll booth were three to five times higher than back-
ground levels (Bruckman and Rubino, 1977; Nicholson et. al., 1971). This sub-
section will consider the possibility of asbestos emissions from brake lining
use.
6.4.1 Published Literature
A number of articles and publications (Rohl e£al., 1976, 1977;
Alste ejt al^., 1976; Jacko and DuCharme, 1973; Jacko e£ al., 1973; Bush et al..
1972; Hatch, 1970; Hickish and Knight, 1970; Lynch, 1968) have discussed the
asbestos emissions from the use of brake linings. Table 6.5 gives a brief
summary of this published data in terms of methodologies and results. As can be
seen from Table 6.5, there are important discrepancies in the results obtained.
6.4.1.1 Discrepancies in Asbestos Content of Emissions or Debris
Lynch (1968), Hatch (1970), Hickish and Knight (1970),
Jacko and DuCharme (1973), and Anderson eit al. (1973) reported figures in the
range of 1% or less for the asbestos content of emissions or debris resulting
from brake lining use. Bush e_t al. (1972) and Rohl ejt al. (1976, 1977) arrived
at figures which are substantially higher, 44% and 2-15% asbestos content,
respectively. While Alste ejt al. (1976) did not arrive at a percent figure,
they did conclude that the major effect of braking appears to be separation of
bunches of fibres and reduction of their average length, but not alteration of
their crystal structure. This conclusion may certainly result in a relatively
high asbestos content for wear debris.
82
-------
Table 6.5. Summary of Published Data - Asbestos Emissions from Brake Lining Use
Publication
Source
oo
u>
Method Used to Collect
Emission or Debris Samples
Lynch. 1968
Hatch. 1970
HlcklKh and Knight.
1970
Bush et_ al., 1972
Anderson e^ al., 1973
Laboratory simulations utilizing brake-testing
machines or dynamometers. Samples collected
on 0.8 u pore size membrane filters.
A dust cloud was generated by using compressed
air jets to remove duat from brake linings
in an auto repair garage. Samples were
collected by means of a hand pump located
in center of dust cloud.
Samples were collected directly from debris
remaining as brake dust and from membrane
filters exposed during brake cleaning
operations utilizing compressed air.
Filter pore size Is not given.
Laboratory simulations utilizing a disc brake
assembly mounted on an Inertlal dynamometer.
Samples were collected on suitable filter
paper.
Laboratory simulations utilising a dine brake
assembly mounted on a dynamometer. Air
samples of wear debris collected down wind
of disc brake.
Method Used •
to Determine
Asbestos Content
of Emission
Debris Samples
Not stated
Not stated
Neutron activation
Transmission electron
microscopy
Asbestos
Particle Size
Distribution
Asbestos Content of
Emission or Debris
Electron micrographs Not discussed
941 of fibers
fell in 2-5 urn
length category.
Only 61 were
longer than 5 urn
Not discussed
Not discussed
Test results
and procedures
precluded a size
distribution esti-
mate
<1Z, except under
severe-stress conditions
1.6X and less
(this figure is not
accurate; see discussion
In Section 6.4.1.1)
"-0.02Z
Jacko and DuCharme,
1973 vcontalns
same data as
Jacko et aJL., 1973)
Samples were generated by operating a standard
American car under typical driving conditions
In Detroit. Michigan. More abusive conditions,
such as fade tests, were also Included.
Brake and rluth assemblies were enclosed by
specially designed collectors. Samples were
collected from 1) dropouts during use, 2) dust
retained In lining assemblies, and -3) airborne
samples collected on membrane filters.
Optical and electron
microscopy
30Z of fibers
were from
0.25-0.50 urn
In length; 60Z
were longer
than 0.5 urn
0.2SZ overall average
(an Independent check
done by Batelle Labs
gave a figure of 0.171Z)
-------
Table 6.5. Summary of Published Data - Asbestos Emissions fro» Brake Lining Use (Cont'd)
to Collet
Eaiasiov or >br;- Saaalc
•ohl et al.. 1976
lee saaBles of aatoaohile brake Jrua dust*
«ere collected fro* aaJntfanare thop* ic
the »ew Tork area.
Method
to Drl< rai-*
Asbestos Conerat
•f
I-r*y
Acbestos
farticl* Size
IHstribotion
Asb«-«t(>« Coateat of
fiBts«ioa er Drt-ris
area electro*
41ffrartim. aW
elertroa •drrofroke
2-1 SI; average of >-*•
MR of fibers Mere Coasts teat with. bc.t
shorter than lover than,
0.4 _a leagth aaaatitalive
deteraiaatloa airlf
by X-ray
diflractoaetry;
ao pereeatages are
OD
fcaaples «ane take* froo fresh aad won brake El
lialags aad froai the ataua.iht.ie aear » aad elertroa
freeway. diffrarttoa
Itojority «ere
^2 .at ia aaxl
llaear dtaeacloa
Bo percent ffgnre
•ohl et al.
1«77
thla i« ba»iraMy a reprlal off tbe Bobl et al..
197b staaj o
-------
The 44X figure computtd by Buah at. al. (1972) la baaed
upon a nautron activation analyaia, which ia a tachniqua for finding tha
elamantal composition of a aampla by Irradiating tha sample with neutrona,
tharaby cauaing tha elements to bacoma radioactiva. Buah alt al. ia caraful to
point out that chryaotila aabaatoa ia a magneelum ailicata and naithar magne-
sium or ailicon are abla to ba determined utilising tha particular technique.
Therefore, aabaatoa content of tha wear dabria waa determined by maana of a
acandium concentration. Scandium waa a trace element (*v< A ppm) praaant in
tha chryaotila uaad in tha experiment. Nautron activation can ba a vary
praciaa and uaaful tachniqua for determining elamantal compoeition; unfortun-
ately, tha aabaatoa content of any particular wear dabria aampla cannot ba
computed by an elemental analyaia. Chryaotila aabaatoa ia a unique cryatal
atructure of a magnaaium ailicata (aaa Section 2.1); heat or othar phyaical
maana can daatroy thia unique structure, tharaby creating a different compound
with different properties. However, the elemental compoaition of tha different
compound will be identical with chryaotila. Rohl et_ al,. (1976) determined
that tha magnaaium:ailicon ratio of an aabeatoa friction material la the same
bafora uaa and after uaa (aa determined from wear dabria via chemical analyaea).
Therefore, the 44X aabaatoa content figura computed by Buah at, al. (1972) does
not rapraaent tha aabaatoa content, but rather it rapraaanta the magneaium
ailicata content. When conaidering wear debria from friction materials,
neithar nautron activation nor chemical analyaea are uaeable techniquea for
analyaia of aabaatoa concentration.
The major conflict to ba raaolvad ia tha high aabaatoa
content auggaatad by Alata (1976) coupled with tha 2-15X aabaatoa content figura
85
-------
obtained by Rohl et al. (1976, 1977) versus the 1% and less figures obtained by
the remaining publication sources listed in Table 6.5. The difference of re-
sults appears to be based upon collection methodologies, analysis techniques,
and interpretations.
6.4.1.2 Collection Methodologies and Particle Size Distribution
The first major consideration of methodology is the type of
samples which were collected. Lynch (1968), Bush e* al. (1972), and Anderson
et al. (1973) collected laboratory samples produced by simulations, while other
researchers listed in Table 6.5 collected samples from automobiles which were
undergoing or had undergone actual driving conditions. Conditions encountered
during actual use may not be totally reproducible in the laboratory; hence, the
asbestos emission factors may be somewhat different. It would seem probable
that samples collected from actual auto use may be more relevant to airborne
emission potential than laboratory simulations.
Jacko and DuCharme (1973) used specially designed collectors
which enclosed brake and clutch assemblies which allowed wear debris samples to
be collected while the test car was being driven on the street. Rohl et al.
(1976, 1977), Alste et^ a!,. (1976), Hickish and Knight (1970), and Hatch (1970)
collected wear debris samples from automobiles in repair shops which perform
brake maintenance.
Another area of consideration is the asbestos particle size
distribution in the wear debris. Rohl et. al. (1976) determined that approxi-
mately four-fifths of the wear debris fibers are shorter than 0.4 ym in length
while Jacko and DuCharme (1973) found that 30% of the fibers were from 0.25-0.50
in length. According to Rohl et al., some of the discrepancies between their
data and those of Jacko and DuCharme may be attributed to Jacko and DuCharme's
86
-------
use of lower magnification (22.000X vs. 42,OOOX), at which fibers shorter than
0.20 ym may not be easily seen or identified on the electron microscopic
screen. Jacko (1978b) attributes the particle size distribution differences
to a mechanical degradation technique utilized by Rohl et al. (1976) but not by
Jacko and DuCharme (1973). Hatch (1970) also produced size distribution
figures, finding that 94% of the fibers fell in a 2-5 ym length range; how-
ever, there is no indication that Hatch attempted to look for fibers shorter
than 2 ym. Alste et al. (1976) found that the majority of particles, which
consisted of small bundles of fibers, had a maximum dimension of £ 2 inn.
The best available data (Rohl e£ al., 1976; Jacko and
DuCharme, 1973; Alste £t al., 1976) indicates that a very high percentage of
the number of fibers, but a small weight fraction, of asbestos present in
brake lining wear debris is shorter in length than 2 ym, with a substantial
portion shorter than 0.5 ym.
6.4.1.3 Analysis Techniques
Hickish and Knight (1970) fail to discuss analysis techniques
used to determine the asbestos content in their wear debris and, also, do not
fully describe collection methods. Under these circumstances, it is difficult
to accept their results at face values. Hatch (1970) is deficient in analysis
methodology also, although it appears that he used electron microscopy in sizing
particles down to 2 ym. Since the Rohl et_ al.. (1976), Jacko and DuCharme (1973),
and Alste et al. (1976) studies are the best studies yet conducted on brake
lining asbestos emissions, a closer examination of the three is warranted.
As seen from Table 6.5, Rohl e± al^. determined their 2-15%
asbestos content from X-ray diffractometry (both continuous and step-scan modes
were used). According to Jacko and DuCharme, asbestos is readily identified
87
-------
when alone or in simple mixtures at high concentrations by the following ana-
lytical methods: X-ray diffraction, thermal methods, microscopy, and infrared
analysis. However, in complex mixtures, or at very low concentrations, the
analysis for asbestos is very difficult. In brake wear debris, the problem is
compounded because the reaction products of asbestos (forsterite, olivine, and
dehydroxylated serpentine) have similar elemental ratios, and several non-
fibrous minerals have similar X-ray diffraction patterns. The only sensitive
method which can be used is microscopy. The accuracy of X-ray diffraction to
determine the asbestos concentration of brake wear debris is beyond the scope
of this report.
Rohl ejt al. further verified chrysotile presence by
transmission electron microscopy and selected area electron diffraction.
"Chrysotile was found, both in fiber and fibril form, with unaltered structure
and chemical composition. Its frequency of occurrence was consistent with, but
lower than, the quantitative determination made by X-ray diffraction analysis.
However, it should be noted that X-ray diffraction analysis is based on both
free fibers and fibers present in clumps; the latter would obscure the presence
of discreet fibers on electron microscopy study."
Alste e_t al. (1976) determined the presence of chrysotile
asbestos by electron microscopy and electron diffraction and concluded that
the major effect of braking appears to be in separating bunches of fibers and
reducing their average length but not in altering their crystal structure. This
is an important result in terms of the following consideration: If only 15%, or
downwards to less than 1%, of wear debris is asbestos, what happens to the major
portions of the asbestos originally present in the brake lining? Lynch (1968),
-------
Hatch (1970), and Hickish and Knight (1970) present a prevalent theory that
"hot spots" created during braking cause the local asbestos fibers to undergo
thermal degradation which results in thermal metamorphosis of the asbestos
into a different mineral, such as forsterite (olivine). Jacko and DuCharme
(1973) found that 20-40% of the wear debris composition was olivine. However,
according to Alste ejt al. (1976) concerning wear debris from brake linings,
"there was no indication from the diffraction pattern of the presence of
forsterite;" this result was in agreement with Rohl ejt al. (1976) who also
could not verify the presence of forsterite. Jacko (19780) did find a reduc-
tion of asbestos and the formation of olivine (a form of forsterite) on fric-
tional heat-affected layers using a combination of X-ray diffraction and
thermogravimetric analysis. Rohl et al. (1976) and Jacko and DuCharme (1973)
discussed other forms of brake lining wear, in addition to thermal wear, such
as abrasive wear and macroshear wear. However, the end result is probably
this: the asbestos present in the original brake lining, excluding the asbes-
tos which is emitted in the wear debris, is converted by thermal or other
physical processes into magnesium silicates or other recrystallized magnesium
silicate structures different from asbestos. In addition to unaltered chryso-
tile fiber in the wear debris, Rohl ejt al. (1976) observed partially altered
and completely recrystallized fibers. Holt and Young (1973) reported that
some of the asbestos fibrils collected in European city air appeared to have
been heated.
6.4.1.4 Other Considerations
The Rohl e£ al. (1976, 1977) studies are based upon a
wider and more random sampling than that of Jacko and DuCharme (1973).
89
-------
Rohl et al. selected wear debris samples from ten random automobiles under-
going brake maintenance in New York and 29 samples from Australia and Europe,
while Jacko and DuCharme!s wear debris samples came only from original auto
equipment, a partial relining, and a relining for the car tested. Alste
et al. (1976) also collected random samples of wear debris from an auto
repair shop, but apparently from only a few cars at most (a much smaller
sampling than Rohl et al.).
Neither Rohl ejt alL (1976), Jacko and DuCharme (1973), nor
Alste et al. (1976) considered, or tested, brake linings manufactured by dif-
ferent companies, different technical processes, or different compositions in
any systematic manner which would be representative of the entire brake lining
industry. Jacko and DuCharme (1973) did use brake linings manufactured by
five different manufacturers, including original and replacement equipment;
however, only "class A" friction materials were used. Class A materials refer
to the better quality, longer wearing friction materials, as opposed to class
B materials, which have inferior wear characteristics. Jacko (1978b) suspects
that the wear debris collected by Alste et al. (1976) may have resulted from
wear of class B brake linings; however, there is no confirmation of this
supposition.
There has been no experimental study conducted which can
confirm or refute the supposition that brake linings made by different com-
panies, processes, and compositions may contribute varying amounts of asbestos
emissions into the environment.
It has been suggested by several Industry spokesmen that
class A material would contribute a smaller asbestos emission to the environ-
ment than class B material. This has not been confirmed experimentally.
90
-------
Industry spokesmen also believe that a larger percentage of foreign cars
imported into the U.S. are equipped with class B brake linings than cars
manufactured domestically.
A recent study by Seshan and Smith (1977) has supported
the work of Rohl e£ al^. (1976) and Alste e£ al. (1976) and contradicts the
work of Jacko and DuCharme (1973). Seshan and Smith (1977) examined automo-
bile brake drum dust using transmission electron microscopy. They found un-
altered chrysotile fibre fondles with some phenolic binder and deformed chryso-
tile which were difficult to determine by selected area electron diffraction.
However, they were able to study the deformations in detail using high resolu-
tion dark-field microscopy and suggested that dark-field microscopy be used to
identify the sources of asbestos fibres found in air pollution samples. These
investigators also examined the brake drum dust with light optical microscopy
*
(LOM) and X-ray diffraction (XRD) and found little (less than IX) chrysotile
and ho forsterite which they concluded was due to the fact that the fibre sizes
and concentrations were below the limits of detection for LOM and XRD.
6.4.2 Emission Quantities
Table 6.6 gives the estimated annual asbestos emissions for
vehicles as computed by Jacko and Du Charme (1973). These figures are based,
in part, upon Jacko and DuCharme's figure of less than 1% (^0.2%) asbestos
content of emission debris. They also made the following estimations:
(1) The total amount of asbestos contained in all of the
automotive brake friction materials sold each year is
about 103 million pounds which corresponds to VL18 million
pounds prior to grinding and drilling.
(2) The total amount of asbestos contained in all automotive
clutch friction materials sold each year is about
4.5 million pounds.
91
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Table 6.6. Estimated Asbestos Emissions* by Jacko and DuCharme (1973) from Vehicles
NO
to
Total Distribution of Total
Number of Annual Asbestos — ~ •• •
Vehicles Emissions (Ib) Drop-Out Airborne
Passenger Cars 96,400,000 60,400 49,470 2,230
Light Trucks 17,100,000 32,300 28,420 940
Medium Trucks 2,600,000 16,300 14,330 470
and Buses
Heavy Trucks 1,200,000 32,900 28,920 950
Miscellaneous 6,615,000 16,300 14,330 470
(motorcycles,
trailers, etc.)
Totals 158,200 135,470 5,060
Percent of Total 85.6 3.2
(Ib)
Retention
8,700
2,940
1,500
3,030
1,500
17,670
11.2
* Includes both brake linings and clutches
-------
Table 6.7. Estimated Asbestos Emissions from Vehicles Using Rohl e£ al. (1976) Figures for Asbestos
Content of Wear Debris
VD
Asbestos Content
of Wear Debris
2% (low)
15% (high)
4.5% (median
Total
Annual Asbestos
Emissions (Ib)
1,520,000
11,400,000
3,420,000
Distribution of Total (Ib)
Drop-Out
1,300,000
9,800,000
2,930,000
Airborne
49,000
360,000
110,000
Retention
171,000
1,280,000
380,000
of average
3-6%)
-------
(3) The combined total of brake and clutch friction material
worn away annually is 123.6 million pounds (117 (brakes) +
6.6 (clutches) - 123.6). Assuming an average asbestos
content of 60%, the amount of asbestos worn away as
friction material wear debris is ^74 million pounds.
Based upon available data from other sources (Clifton, 1977;
U.S. Bureau of the Census, 1972, 1975), the estimations made above are quite
reasonable and are probably good figures to use in emission computations.
Table 6.7 lists the estimated asbestos emissions using the
Rohl e_£ al. (1976) figure for the asbestos content of wear debris. Computations were
made using the same assumptions and method as Jacko and DuCharme (1973); the
only variation is the use of different asbestos content percentages. Rohl et al.
(1976) arrived at an average asbestos content figure of 3-6% (therefore, a
median of 4.5% is listed in Table 6.7) and high-low values of 2-15%.
A comparison of Table 6.6 and 6.7 reveals that the total annual
asbestos emissions reported in Table 6.7 (4.5% median) is nearly 22 times
higher than the total reported in Table 6.6. The focal point of the difference
is the percentage of asbestos which survives in the wear debris.
Jacko and DuCharme (1973) determined that approximately 3% of
the asbestos emission become airborne. Based upon sample concentrations
collected at freeway exits, Alste e£ al. (1976) concluded that only a small
fraction of the total dust formed becomes airborne, which is consistent with
Jacko and DuCharme (1973) and Anderson e£ a.1. (1973).
6.4.2.1 A Hypothetical Calculation
As mentioned earlier in Section 6.4, asbestos fibers have
been monitored in ambient air samples by Holt and Young (1973), Alste et al.
(1976), and Nicholson et_ al. (1973). Selikoff et. al. (1972) monitored ambient
94
-------
concentrations of asbestos in the New York City area and determined the follow-
ing concentrations:
2
Site Concentrations (ng/m )
Manhattan 25-60
Bronx 25-28
Brooklyn 19-22
Queens 18-29
Staten Island 11-21
Philadelphia 45-100
Ridgewood, N.J. 20
Port Allegany, Pa. 10-30
Bruckman and Rubino (1975) reported that asbestos levels in
non-urban and remote non-urban air are typically less than 1 ng/m , while urban
air usually has levels below 30 ng/m . From thirty selected monitoring sites
in Connecticut, Bruckman and Rubino (1977) found the following concentrations:
3
1) less than 10 ng/m in areas removed from emission sources
3
2) above 30 ng/m near each of four industrial users
3 3
3) 10 ng/m to 25 ng/m adjacent to toll plazas where autos commonly
apply brakes
The above data gives a general idea of the magnitudes of
various background levels of ambient air concentrations of asbestos. The fol-
lowing hypothetical case is intended to project a theoretical magnitude of
contamination from friction material use.
Hypothetical Case; This calculation attempts to estimate
the levels of asbestos which may be added to urban environments as a result of
wear from automobile brake linings. As noted in Tables 6.6 and 6.7, the amount
of asbestos emitted by brake linings has been estimated to range from 2.5 to
55 tons airborne per year. The calculation below will assume a nationwide
emission average of 10 tons per year. New York City will be considered because
95
-------
of available air monitoring data. New York City has a population of approxi-
mately 7.9 million people and an area of roughly 300 sq. miles. It is assumed
that friction material use follows population; therefore, of the estimated
10 tons of emissions from brake linings, NYC would be responsible for:
7.9 million (NYC pop.) 14 ng
210 million (US pop.) X 10 tOns " °-376 tOns " 3'4 X 10 £
14
This value of 3.4 X 10 ng/yr translates into an emission of roughly
9.34 X 10 ng/day. The volume of air 1000 ft. above street level over NYC is
11 3
about 2.5 X 10 m . It is assumed that the daily emissions of asbestos
become equally distributed throughout the air 1000 ft. above street level.
Therefore, the ambient air concentration of asbestos which results from daily
brake emissions would be:
9.34 X 1011 ng/day _ ,3
,, ,—*- • 3.7 ng/m
2.4 X 10-1 in
The resulting estimate is on the same order of magnitude as
available monitoring data. It should be remembered that this calculation is
totally theoretical and is not intended as proof that brake emissions are re-
sponsible for all asbestos emissions monitored in ambient air. Many other
factors need consideration in terms of brake emissions to air, such as weather
effects upon airborne fibers and actual distribution patterns from emission
sources. The potential for the sizes of particles emitted to remain airborne is
a major consideration.
6.4.3 Human Exposure to Asbestos Emissions During Brake Lining
Maintenance and Repair
In the United States, an estimated work force of at least
900,000 auto mechanics and garage workers is potentially exposed to asbestos
in the servicing of both brake and clutch linings (Rohl e£ al., 1976).
96
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Measurable concentrations of asbestos fiber have been observed and reported in
the work environment of workmen involved with brake and clutch linings main-
tenance and repair (Hickish and Knight, 1970; Hatch, 1970; Boillat and Lob,
1973; Rohl et.al., 1976).
When a vehicle is brought into a repair shop for brake lining
inspection or replacement, the wheel is removed and the loose dust is removed
from the drums and back plates, generally by means of a compressed air jet. A
cloud of dust is produced by this air jet which is visible for several minutes.
Table 6.8 lists the fiber concentrations which were measured as a result of the
dust cloud by the most relevant study (Rohl et al., 1976) to American standards
of exposure; also given are concentrations measured for common truck servicing
ope'rations.
The result of the Rohl et_ al. (1976) study indicates that it is
common for OSHA asbestos-fiber concentration standards to be exceeded during
brake cleaning operations. It should be noted that fiber counts made during
this study were in accordance with procedures adopted by OSHA. Essentially, the
analysis consists of counting fibers 5 to 100 ym using phase contrast microscopy
at a magnification of 400X.
Section 6.4.1.2 revealed that most of asbestos present in wear
debris is much smaller than 5 ym. Rohl et al. (1976) estimated that 80% of
the fibers present are shorter than 0.4 ym. Accepting these results, it is
obvious that the asbestos exposure during brake servicing may be a great deal
higher than is indicated by OSHA test standards.
97
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Table 6.8. Asbestos Concentration During Automobile and Truck Brake Service*
(Rohl e^ al., 1976)
Fiber Concentration
Auto -
Truck
Truck
Operation
Blowing dust out of
brake drums with
compressed air
- Renewing used
linings by grinding
- Beveling new linings
Distance
(ft)
3-5
5-10
10-20
3-5
3-5
Number
of
Samples
4
3
2
10
5
(fibers/ml)
Mean
16.0
3.3
2.6
3.8
37.3
Range
6.6-29.8
2.0-4.2
0.4-4.8
1.7-7.0
23.7-72.0
* Fibers 5-100 \m in length, counted by optical microscopy.
98
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6.5 Alternatives to Asbestos as a Friction Material
6.5.1 The Role of Asbestos in Friction Linings
Originally, automotive brake linings were made from a cotton
textile material which was Impregnated with drying oils and cured to form a
strip of material which was flexible, conformable, and mechanically very strong.
The main purpose of the drying oil was to protect the cotton from attack by
atmospheric oxygen, which, even at the temperatures reached by early brakes,
would have resulted in burned cotton had its surface been exposed to the air.
As brake operating temperatures increased, it was found that cotton started
to degrade and lose its strength even though still protected from oxygen
attack. In other words, the cotton suffered thermal degradation instead of
oxidative degradation (Hatch, 1970).
Around 1910, a technological breakthrough was achieved when it
was discovered that asbestos could be woven and used to replace cotton because
asbestos neither burns nor loses its strength below about 500°C. When braking
operations became more severe, in the 1940*s, brake linings began to be manu-
factured by moulding powdered resins with short asbestos fibers. This made
possible the inclusion of various property modifiers to aid in the braking
operations (Hatch, 1970). As described in Section 6.2, this is the current
method of brake lining manufacture.
Any alternative material to asbestos in brake linings has to
compete with asbestos's properties of strength, high temperature protection,
insulation, and good frictional properties.
6.5.2 Alternatives in Brake Linings
At this time, there are no commercially available, asbestos-free
brake linings intended for use in automobiles with drum brakes (Aldrich, 1977;
99
-------
Rosenburg, 1977). This is not the case when considering disc brake pads, as
will be explained later. Currently, nearly all of the major brake lining
manufacturers are engaged in research and testing programs to develop asbestos-
free drum brake linings for automobiles; limited commercial success has been
achieved only with semimetallic friction material. It should be noted that,
if by "alternative" we mean a new or better fiber which might shortly be
available as a replacement for asbestos in conventional brake linings, the
chances are actually quite remote.
The possible asbestos alternatives which are being tested and
considered are discussed below (Hatch, 1970; Aldrich, 1977; Rosenburg, 1977):
(1) Glass Fiber - overall strength is lower than that of
asbestos, but strong enough for friction material
applications. Unfortunately, at the temperatures
reached by braking operations, glass fiber melts,
even in depth below the operating surface.
(2) Steel Wool - compared to asbestos, the overall strength
is lower and the cost is much higher. In addition, the
material hardness of steel wool damages the brake drums.
(3) Mineral Wools - overall strength is very low and brittle
to the extent of limiting mixing processes.
(4) Carbon Fiber - the main properties of carbon fibers are
generally good, but still somewhat inferior to asbestos.
A major consideration is the cost, which is a great deal
more than asbestos.
(5) Sintered Metals and Cermets - these materials are now
being used to manufacture brake linings for railroad
cars and airplanes. Eventually, these materials may
be developed into practical applications for automo-
biles. At this time, the wear-resistance is not good
enough for automotive uses and the cost is too high.
There are two good reasons why the industry is attempting to
develop asbestos-free products. First, there is the possibility of a govern-
mental ban on asbestos applications which emit asbestos fibers into the
100
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atmosphere. And secondly, asbestos-free manufacture would eliminate the need
for asbestos-environmental control devices in the workplace and would elimin-
ate a health hazard to employees, thereby eliminating a substantial expense.
6.5.3 Alternatives in Disc Brake Pads
It is purely fortuitous that the friction materials used in
disc brakes are designed to a stronger shape than in drum linings; that is,
more or less square or circular pads of considerable thickness are supported
by a metal plate of adequate thickness. Therefore, the friction material does
not have to stand up to handling during assembly, does not have to withstand
riveting, and could, from the point of view of bulk mechanical strength alone,
be made without a high loading of fibrous reinforcement of any kind. There
remains, however, thermal shrinkage and thermal shock, and in order to prevent
the formation of tensile cracks normal to the operating surface, a percentage
of asbestos fibre is still retained (Hatch, 1970).
Nevertheless, it cannot be said that the use of asbestos in
disc brake pads remains a technical necessity (Hatch, 1970); in fact, commer-
cially available disc pads have been developed for automotive uses which do
not use asbestos (Aldrich, 1977). Table 6.9 lists a typical composition for
this asbestos-free disc pad. Cost of the asbestos-free pad is somewhat higher
than the asbestos pad.
101
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Table 6.9. Asbestos-Free Composition of a Disc Brake Pad (Aidrich, 1973)
(vol. %)
Carbon 45
Iron Powder 25
Steel Fiber 10
Phenolic Resin 20
(manufactured by common methods)
6.5.4 Alternatives in Clutches
Borg-Warner Corporation, a major manufacturer of clutches, is
currently engaged in the testing of asbestos-free friction materials intended
for use in clutches (Rosenburg, 1977). The asbestos-free materials being tested
have been developed by the major friction-material producers such as Raybestos-
Manhattan and Abex. To date, none of the alternatives tested have been as good
as asbestos.
6.6 Quantities of Asbestos Released to the Environment from Manufacture
Listed below in Table 6.10 are the estimated quantities of asbestos
released to the environment from asbestos friction products manufacture. The
estimates in Table 6.10 are not intended to be considered precise quantities.
The estimates are based upon available data and engineering assumptions and are
intended only to project a general magnitude of release.
102
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Table 6.10. Estimated Annual Environmental Release of Asbestos from Friction
Material Manufacture (SRC estimate)
(short tons) Comment
To waste dump or landfill:
Baghouse fine and product scraps 8,130 Mostly free-fibers*
Wastewater solids from air
scrubbers 6.7 Wet free-fibers*
To water:
Wastewaters from air scrubbers 0.3 Free-fibers*
To air:
Baghouse emissions 0.61-6.0 Free-fibers*
Air scrubber emissions 0.14 Free-fibers*
* These "free-fibers" may be coated with resin, however, by "free" the intention
is to Indicate a potentially respirable fiber.
The estimates in Table 6.10 were derived by methods which are explained in the
following subsections.
6.6.1 Release from Baghouses and Product Scraps
Jacko and DuCharme (1973) have reported that the amount of
asbestos contained in all of the automotive brake friction materials sold each
year is about 103 million Ibs., which corresponds to about 118 million Ibs.
prior to grinding and drilling. This indicates that approximately 12.7% of the
asbestos is lost to product scraps. The grinding and drilling of brake linings
during manufacture can release as much as 30% of the lining material as waste
(EPA, 1974). Even with the relatively high price of asbestos fiber, the asbes-
tos contained in product scraps is not recovered for reuse (Gregg, 1974). Once
the resin has set up, it is not regarded as economical to break it down to
salvage the fiber. These wastes are normally disposed to landfills or waste
piles.
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In most cases, the emissions from grinding and drilling opera-
tions are collected in baghouses (EPA, 1974). These baghouse wastes can
amount to as much as 13.5 tons per month for a plant producing 40,000 shoes
per day (EPA, 1974). To determine the industry-wide quantity of asbestos
disposed from baghouses and product scraps, the following assumptions are
made: 1) about 12.7% of the total asbestos consumed in friction materials is
lost to scraps and. 2) about three-fourths of this total is collected in
baghouses and the remaining one-fourth is collected by vacuum cleaning opera-
tions or as damaged product. Based upon a total asbestos consumption of
64,000 tons for all friction materials in 1976 (Clifton, 1977), the amount of
asbestos lost to product scraps would be about 8,130 tons. Baghouse collec-
tions would roughly amount to 6,100 tons and the other scraps would amount to
roughly 2,030 tons. Virtually all of the asbestos collected in baghouses is
in a potentially respirable form. Disposal operations of these baghouse
wastes can potentially release fibers into the atmosphere (EPA, 1974). It is
virtually impossible to quantify the amount of asbestos fibers released during
disposal operations without monitoring data, of which there are none.
In most of the plants making friction materials, air emissions
are controlled by baghouses; however, in a few plants, wet dust collectors are
used and a wastewater results (Gregg, 1974). Asbestos releases from wet dust
collection are discussed in the next subsection.
The efficiency of an asbestos baghouse collector, in terms of
atmospheric emissions, has been monitored to have an efficiency of nearly 99.991
(Siebert e_t al., 1976). Applying this efficiency to the estimated quantity of
6,100 tons of asbestos collected by baghouses indicates that the asbestos fiber
104
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emissions to the atmosphere would be 0.61 tons annually. However, in Section 7.3.1,
a baghouse emission factor has been developed which estimates that 1.34 Ibs. of
asbestos fibers are emitted per year per each 100 CFM rating. The exhaust air
flow of a medium size friction material plant has been estimated to be in the
neighborhood of 30,000 CFM (Gregg, 1974). Therefore, using the 1.34 Ib.
emission factor indicates that a medium size plant would emit about 400 Ibs. of
asbestos fibers each year. Table 6.2 lists over 30 friction material plants;
therefore, this method predicts that roughly 6 tons of fibers would be emitted
to the atmosphere industry-wide. As explained in Section 7.3.1, the 1.34 Ib.
emission factor is a "worst possible" case. The difference in estimates,
0.61 tons and 6.0 tons, is significant. There are not enough monitoring data
available to make a precise estimate.
6.6.2 Release from Wet Dust Collection
Process wastewaters containing asbestos fibers are not generated
by friction material manufacturing operations. However, waters used to clean
fibers and particulates from air do contain asbestos, and these wastewaters are
released by some plants. Wet dust collection is rarely used in the asbestos
industry. Gregg (1974) identified only four friction material manufacturing
plants that discharge wastewaters from wet dust collection. At all of the known
plants, the wastewaters are clarified before discharge to surface waters.
Currently, the number of plants using wet dust collection is not known; there-
fore, the estimates projected below are based upon Gregg's (1974) data.
The effluent waste load from wet dust collection for a typical
plant is estimated to be 25 Ibs. of suspended solids per day (Gregg, 1974).
Assuming the suspended solids are about 50% asbestos (because asbestos is
105
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roughly 50% of the friction material's raw content) and an average work year
of 50 weeks at 5.5 days per week, then about 3,450 Ibs. of asbestos are col-
lected by wet collection each year at a typical plant. Four plants would
collect about 13,800 Ibs. or roughly 7 tons of asbestos fibers. Clarification
may remove approximately 95% of the suspended solids. The sludge collected
from clarification would therefore contain about 6.7 tons of asbestos fibers;
this sludge is disposed of in landfills. The clarifed water released to
surface waters would contain about 0.3 ton of asbestos.
Wet-type air scrubbers normally operate in the range of 98%
efficiency. Therefore, based upon a collection of 7 tons, these wet dust col-
lectors would emit about 0.14 ton of fibers into the atmosphere.
106
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7.0 ASBESTOS-CEMENT PIPE
Asbestos-cement pipe, which was developed about 60 years ago, Is a durable,
inexpensive pipe material extensively used in underground applications.
Asbestos-cement (A-C) pipe is resistant to corrosion, both internally and
externally, has high enough strength to withstand pressure pumping, and does
not rust and cause discoloration of water.
The two major applications for A-C pipe are water distribution systems and
sewer service. Small amounts of A-C pipe are used as telephone and electrical
wire conduit and air ducting. It is estimated that roughly 70-75% of all the
A-C pipe produced is used for water supply with sewer pipe accounting for 20-
25% of all uses nationwide (Jackson, 1977). In the eastern United States, A-C
sewer pipe currently outsells A-C water pipe by approximately three-to-one;
however, in most other sections of the country the water pipe outsells the
sewer pipe by three-to-one (Gresham, 1977; Lawless, 1977). This is due pri-
marily to factors of climate and topography and the fact that the major water
supply lines in the East have been in existence for years, whereas population
expansion in other sections of the country has created a demand for new water
supply systems. The largest markets for all types of A-C pipe are west of the
Mississippi River (Jackson, 1977), as this is the area of the country in which
the newer population centers are forming.
A-C pipe is produced in sizes ranging from 4 to 32 inches in diameter
(Daly e£ al., 1976). The water supply pipe, a pressure pipe, has a somewhat
thicker and stronger casing than the sewer pipe. Much of the water supply pipe
is pressure-tested before shipment.
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In 1974, an estimated 1.5 million miles of A-C pipe were in service world-
wide, of which more than 200,000 miles were in the U.S. (Olson, 1974). Also in
1974, it was estimated that over 30% of all the water distribution pipe being
sold in the U.S. was made of asbestos-cement (Johns-Manville, 1974). Currently
(1977), it is estimated that roughly a quarter of a million miles of A-C pipe
are in service nationwide with approximately 10 to 15 thousand miles of new
pipe being produced each year (Jackson, 1977). Current figures for A-C pipe's
market share of the water distribution and sewer market are not available;
however, it is generally thought that the water distribution share has not
changed significantly from the 1974 figure given above.
7.1 Use Quantity. Shipment Values, and Industrial Firms
U.S. demand for asbestos fiber in A-C pipe has ranged from 134 to
222 thousand short tons during the 1967-1976 period; in 1976, about 140 thou-
sand tons were consumed for this purpose (Tables 4.9 and 4.10, p. 46). Accord-
ing to the 1976 figures, about 19.3% of the total U.S. market for asbestos was
consumed in the production of A-C pipes. This is the second largest single use
of asbestos fiber; roofing is the largest use.
The trend in the value of shipments of A-C pipe is shown in Table 7.1.
A growth rate of five to seven percent has been projected for the A-C pipe
market in the next three to seven years (Igwe, 1974). However, industry
spokesmen indicate that the market for A-C pipe is, at present, stable (Jackson,
1977; Gresham, 1977). Significant increases or decreases in sales are not
projected in the foreseeable future.
Table 7.2 lists the U.S. manufacturers of A-C pipe along with their
respective sales in 1975. The four companies (13 plant locations) listed in
108
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Table 7.1. Shipment Value and Quantity of Asbestos-Cement Pipe
(U.S. Bureau of the Census, 1972)
Total Product Shipments, including interplant transfers
SIC
Product
Code Product
1975*
Quantity Value
X103 tonal ($ million^
1972 1967
Quantity Value Quantity Value
(103tons) ($ million) (103tons) ($ million)
Asbestos-Cement Pdts.
H 32927 73 Pipe, conduit, ducts*?
S , 900 197 870.1 143.3 840.1 118.6
32927 75 Pressure pipe
*SRC Estimates
Note: All dollar values are actual values for that year.
-------
Table 7.2. Major U.S. Manufacturers of Asbestos-Cement Pipe
Manufacturer
Johns-Manville
Certain-Teed Corp.
CAPCO (Cement-Asbestos
Products Co., Div. of
ASARCO)
Flintkote
Plant Location
Estimated 1975*
Sales of
Asbestos-Cement Pipe
(Millions of Dollars)
Manville, NJ
Long Beach, CA
Waukegan, IL
Denison, TX
Green Cove Springs, FL
Stockton, CA
St. Louis, MO
Hillsboro, TX
Ambler, PA
Santa Clara, CA
Riverside, CA
Van Buren, AR
Ragland, AL
Ravena, OH**
TOTAL
$78.0
29.0
15.0
14.4
5.7
10.4
8.7
7.2
4.6
2.2
8.7
4.3
8.7
196.9
*Economic Information Systems, Inc., SRC Estimates
**Closed 1976
110
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Table 7.2 account for more than 95% of the total A-C pipe production in the
U.S. (SRC estimate). Johns-Manville is clearly the industry leader in the
production and sales of this product.
7.2 Manufacturing Process Technology
A description of the manufacturing process is Included here to
identify the sources from which asbestos is released to the environment from
the process. Figure 7.1 gives the graphic illustration.
Asbestos-cement pipe normally contains from 15-25% asbestos by
weight, usually of the chrysotile variety. Carton (1974) indicates an asbes-
tos content range of 10-70%; however, such extremes are used for specialty
items only. In 1976, 83.5% of the total amount of asbestos used in A-C pipe
was chrysotile, 14.5% was crocidolite, and 2% was amosite (Clifton, 1977).
Crocidolite is used in sewer pipe to increase production through faster filter-
ing rates. Portland cement content varies from 25-70%. The remaining raw
material, from 5-35%, is finely ground silica. Finely ground solids from
damaged pipe are used by some plants as a filler material, up to 6% (Carton,
1974). The average asbestos content of asbestos-cement pipe, by weight, can
be calculated to be about 18%. This figure was derived by comparing the total
A-C pipe shipments in 1972, 870.1 thousand tons (Table 7.1), with the total of
asbestos used in A-C pipe production in 1972, 154 thousand tons (Table 4.9,
p. 46). Harwood and Ase (1977) have reported an average asbestos content
figure of 25%, while Jackson (1977) has indicated that the asbestos content is
normally below 20%.
The manufacturing steps for the production of A-C pipe may vary
slightly from plant to plant; however, the general overall operations are
111
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RAW MATERIALS
STORAGE
PROPORTIONING
DRY MIX
WATER
STEAM
RECYCLED SOLIDS
RECYCLED WATER
WET MIX
FORMING
CURING
(AUTOCLAVE)
~l
WASTEWATER (
CLARIFICATION
(SAVE-ALL)
I
SLUDGE
CONDENSATE
WATER
PIPE END
FINISHING
SOLIDS
RECYCLED
HYDROSTATIC
TESTING
WASTEWATER
FINISHING
STORAGE
CONSUMER
Figure 7.1. Asbestos-Cement Pipe Manufacturing Operations, Wet Mechanical
Process (Carton, 1974)
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basically the same.
"After thorough blending of the raw materials, the mixture is
transferred to a wet mixer or beater. Underflow solids and
water from the save-all are added to form a slurry containing
about 97 percent water. After thorough mixing, the slurry is
pumped to the cylinder vats for deposition onto one or more
horizontal screen cylinders. The circumferential surface of
each cylinder is a fine wire mesh screen that allows water to
be removed from the underside of the slurry layer picked up
by the cylinder. The resulting layer of asbestos-cement
material is usually from 0.02 to 0.10 inch in thickness. The
layer from each cylinder is transferred to an endless felt
conveyor to build up a single mat for further processing. A
vacuum box removes additional water from the mat prior to its
transfer to mandrel or accumulator roll. This winds the mat
into sheet or pipe stock of the desired thickness. Pressure
rollers bond the mat to the stock already deposited on the
mandrel or roll and remove excess water. Pipe sections are
removed from the mandrel, air cured, steam cured in an auto-
clave, and then machined on each end." (Carton, 1974)
It can be noted that, in general, the method used to make A-C pipe is very
similar to the methods to make A-C sheet, asbestos paper, and asbestos mill-
board .
Wastewaters from the asbestos-cement product manufacture are treated
by methods which vary from plant to plant. Treatment can range from no treat-
ment at all to 100% recycle. The most common treatment of wastewaters is
sedimentation; some form of sedimentation is applied at nearly all plants in
the asbestos industry (Carton, 1974). Sedimentation involves allowing the
process wastewaters to settle out their suspended solids or wastes in either a
clarifier unit or a specifically constructed pond. The sludge and solid wastes
which are settled are usually hauled away to landfills. The sedimentation
process can be complimented by pH control and by additions of chemical agents
to improve the efficiency and time requirement for sedimentation. Considering
the entire asbestos industry, the overall efficiency of sedimentation units, or
113
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clarifiers, is estimated to be about 94-96% (Carton, 1974). Neutralization,
or pH control, is practiced by 30% of the A-C pipe plants (Carton, 1974).
Water discharged from sedimentation is both recycled to the manufacturing
process and/or released to surface waters or sewers, depending upon the indi-
vidual plant. A number of plants are currently recycling all waters.
7.3 Quantities of Asbestos Released to the Environment from Manufacture
Listed below in Table 7.3 are the estimated quantities of asbestos
released to the environment from A-C pipe manufacture. The estimates in
Table 7.3 are not intended to be considered precise quantities; the data re-
quired for precise estimates are simply not available. The estimates are based
upon available data and engineering assumptions and are intended only to pro-
ject a general magnitude of release; These qualifications are also .applied to
all releases from manufacturing estimated in following sections of this report.
Table 7.3. Estimated Annual Environmental Release of Asbestos from A-C Pipe
Manufacture (SRC Estimates)
Quantity
(short tons)
Comment
To Waste, Dump, or Landfill:
rejected pipe & scrap 10,680
baghouse fines 737
process wastewater solids 480
To Water:
from process wastewater 11-12.5
To Air:
from baghouse emissions 0.1-2.2
fibers bound in cement matrix
free fibers
fibers bound in cement matrix
fibers coated with cement
free fibers
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In addition to the emission quantities estimated in Table 7.3, a
comment has been added to identify the emissions as either free-fibers or
fibers bound in a matrix. This is an important consideration. Free-fiber
emissions cause a much greater concern due to the inhalation potential with
human exposure. Fibers bound in a matrix are generally not susceptible to
human exposures unless acted upon by some mechanical force, such as grinding
or crushing, or incineration.
The quantitative estimates in Table 7.3 were derived by methods
which are discussed below.
7.3.1 Release From Baghouses and Rejected Pipe and Scrap
Harwood and Ase (1977) have estimated that 5-10% of the product
material, for asbestos-cement products in general, is dumped as scrap, of
which 10% is fine dust from baghouse collection and 90% is coarse scrap from
trimmings and breakage and from products which have failed quality assurance
testing. In a model plant projection based upon Johns-Manville's A-C pipe
plant in Denison, Texas, Harwood and Ase (1977) have determined the following
relationships:
(1) daily production of A-C pipe is about 220 short tons for six days
per week for 50 weeks per year
(2) product composition is 45% portland cement, 30% quartz silica,
and 25% asbestos; dry waste emissions have the same composition
(3) reject pipe and scrap = 14.5 short tons per day
(4) fines collected in baghouse - 1 short ton per day
Based upon a total A-C pipe production of 900,000 tons per year
(Table 7.1), the industry-wide total of reject pipe and scrap would be about
59,334 tons and the total fines collected from baghouses would be 4,092 tons.
Although Harwood and Ase (1977) have reported an asbestos content of 25%, in-
dustry spokesmen believe that an 18% figure is more accurate for the entire
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industry. Therefore, an 18% asbestos fiber composition assumption of the
wastes yields the asbestos release quantities given in Table 7.3.
The main focus of the Harwood and Ase (1977) study was to examine
the asbestos emissions from waste piles created by manufacturing plants.
Their work was done at Johns-Manvilie's plant in Denison, Texas. At this
particular plant the fines from the baghouse were dumped in the waste area, in
a free-fiber state, along with the reject pipe and scraps, and then all of the
wastes were crushed together by a bulldozer. A waste pile is apparently a
common feature of most asbestos-cement manufacturing plants; additional moni-
toring of waste piles for asbestos emissions is contained in Harwood and
Blaszak (1974). Harwood and Ase (1977) monitored rather sizeable fiber emis-
sions from the Denison plant's waste pile} however, a large degree of these
emissions was attributable to the free-fiber state of the baghouse fines; it
was assumed that 0.01% of the rejected pipe became airborne during crushing.
However, it is not clear that all industry plants dispose of their baghouse
fines in this manner. Trosper (1976) notes that there are basically three
•
choices of disposal of asbestos dust collected by a baghouse: (1) one can
pelletize the dust that one has collected; (2) one can cast cakes out of it
using cement or some sort of a solidifying matrix that encapsulates the mater-
ial; or (3) one can reprocess the material. In general, the fibers collected
by baghouses are too short to be reprocessed back into A-C products because
fine fibers add no strength to the cement matrix. Several industrial spokes-
men indicated that some baghouse fines are mixed with cement and then disposed
in landfills. Therefore, referring to Table 7.3, some of the dumped fines are
encapsulated by cement and are not in a free-fiber state.
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Harwood and Ase (1977) and Harwood and Blazsnak (1974) have concluded
that waste piles of asbestos manufacturing plants pose a potential emission
threat to populations within their proximity. However, it is not possible to
quantify potential emissions from these waste piles industry-wide because of
variations in climate, moisture, and operating procedures. Therefore, no
attempt has been made to do so.
Speaking in terms of the overall asbestos industry, and not Just the
A-C pipe segment, control of atmospheric emissions of asbestos has been made
mandatory under Section 112 of the Clean Air Act (Siebert e_t al., 1976). It
is estimated that over 95% of the controls in asbestos manufacturing and
fabricating operations are by means of exhaust ventilation (Weaver, 1976).
Filtering of these exhausts is commonly done by baghouses with fabric filters.
Siebert et al. (1976) have studied the efficiency of asbestos baghouse filters
and have concluded, "for all the fabrics and values of the baghouse operating
parameters tested, the mass efficiencies of asbestos collection exceeded 99.99%."
However, even while obtaining such high efficiencies, Siebert e£ aJL. (1976)
reported that extremely high numbers of small fibers may still be emitted;
typical outlet concentrations of asbestos fibers emitted were found to be on
the order of 108-109 fibers/m3 (for fibers > 0.06 ym) and 105-107 fibers/m3
(for fibers _> 1.5 urn).
Air exhaust and ventilation is usually measured in CFM (cubic feet
per minute). Assuming a six day work week, a 100 CFM exhaust rating would
exhaust about 4.3 x 10 cubic feet per year. Therefore, the following compu-
tation can be made which will estimate an average quantity of asbestos emitted
from a baghouse filter per year per 100 CFM rating. The monitored emission
Q Q q Q o
concentration of 10 -10 fibers/m is averaged as 5 x 10 fibers/m ; also,
117
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3
10 asbestos fibers have been estimated to equal one nanogram (Bruckman and
Rubino, 1975):
5xl08 fibers x 1 m3 x 10"9 grams x 1 Ib x 4.3xlQ7 ft3
m3 35.31 ft3 103 fibers 453.6 grams yr
1.34 Ib asbestos fiber emitted
yr
100 CFM rating
The figure calculated above must be considered to be a "worst possible"
emission factor. The reason for this is a controversy concerning the use of a
conversion factor to convert fiber numbers into weight. Above, we used the
o
Bruckman and Rubino (1975) factor of 10 asbestos fibers per nanogram. Other
conversion factors have been developed but their validity has been questioned
(NIOSH, 1976). NIOSH (1976) states that attempts to formulate such a conver-
sion have generally been unsuccessful because variables are exceptionally
large. For example, ambient levels are generally determined using electron
microscopy, whereas phase contrast microscopy is used to measure occupational
exposures. In addition, techniques used to prepare samples for electron
microscope observations may cause alterations in fiber size distributions. In
NIOSH1s (1976) review of conversion formulations attempted, they noted that
all researchers produced large variations in relationships as evidenced by
large geometric standard deviations.
The following is a brief review of weight assessment from fiber
numbers to produce a conversion factor. Lynch et. al^ (1970) published results
showing that one nanogram of asbestos may be roughly equivalent to 6.7-46.5
fibers > 5 ym, depending upon the industrial operation involved. Nicholson ejt
al. (1975) generated data which showed that one nanogram of asbestos ranged
118
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from none detected to 6,570 fibers > 5 ym by phase contrast microscopy. By
averaging the data, it was calculated that one nanogram was equivalent to
52 fibers > 5 ym in length. Nicholson (1973) showed one nanogram of amphibole
fibers to be equivalent to 604-108,000 amphibole fibers by electron microscopy,
with an average of 30,600 fibers/ng. Dement e£ al. (1975) provided additional
data for the amphiboles conversion; they calculated that one nanogram was
equivalent to 1,200 total fibers by electron microscopy or 400 fibers > 5 ym
in length by phase contrast microscopy. Bruckman and Rubino (1975) have sug-
gested a conversion ratio of 20 asbestos fibers > 5 ym in length, as determined
by optical microscopy, per nanogram of asbestos. This figure is for chrysotile
and is consistent with the results of Lynch e£ aJL (1970) and only 2.5 times
smaller than the average produced by Nicholson ejt al. (1975). Lynch e£ al.
(1970) additionally determined that about 2% of the total number of fibers are
observable by optical microscopy as compared to electron microscopy. This
gives the derivation of 1,000 fibers per nanogram observable by electron micro-
I
scopy. This appears to be the best conversion factor available and it is
therefore used in this report. It should be noted that use of this conversion
factor for determining quantities of asbestos released in process wastewaters
resulting from manufacturing gave results which were remarkably consistent with
results determined by completely different methods (see Section 7.3.2, 8.3.2).
The problem with using the conversion factor for baghouse emissions
is that the fibers which are emitted are extremely small, but the factor was
determined by averaging both large and small fibers. Therefore, the emission
factor of 1.34 Ibs. emitted per 100 CFM rating is probably too high. However,
it does give us an opportunity to make some very rough emission estimates.
119
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The amount of asbestos fiber •mlttid by baghouses, during operstions,
can now be estimated by two separate methods for A-C pip* manufacturing plants.
First, from Table 7.3, about 1,023 tons of ssbsstos fibsrs srs collsctad by
baghousts industrywide par yaar. Assuming that aach baghousa has an afficlancy
of 99.99X (Siabart a_t al_., 1976), than an induatry total of about 0.1 tons of
fibars ara emitted per yaar.
The second method of estimating the aabsstos emissions from baghousa
operations makes use of the emission factor for aach 100 CFM rating which was
calculated above. The following assumptions ara made: (1) an average A-C pipe
plant contains about 10 cubic feet 6f space to be ventilated, and (2) about
IS air changea per hour are made. Whan the total air volume per yasr is cal-
culated from these assumptions and then applied to the emission factor of
1.34 Ibs. asbestos fibers emitted par year 100 CFM rating, the results indicate
that an average A-C pipe plant emits about 336 Ibs. of fiber per year from
baghouses. Since there are 13 plants (Table 7.2), the industrywide emission
would total about 4,368 Ibs. or about 2.2 tons. This total is higher than the
0.1 ton estimated by the first method. It should be remembered that the
1.34 Ibs. emitted per 100 CFM rating factor is a "worst possible" emission,
as explained earlier; therefore, the 2.2 ton estimation may be too high.
However, if a baghouse operates at anything lass than 99.99% efficiency, then
the 0.1 ton estimation could be significantly increased.
7,3.2 Release From Process Wastswaters
The raw water discharge from the typical A-C pipe manufacturing
process contains approximately 6.3 Ibs. of suspended solids per ton of product
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produced (Carton, 1974). The auapended solids are comprised of both organic
material! and inorganic matariala, Organic materials can includa great*, tar,
oil, fata, various fibara, sawdust, etc., whila tha inorganic matariala can
includa aabaatoa, aand, ailt, clay, and camant. "Tha aabaatoa fibar content of
tha (auapandad) aolida la raportad to ba relatively low, with tha bulk of the
aolida originating aa cement, silica, clay, and other raw matariala" (Carton,
1974). For A-C pipe production we assumed that the auapanded aolida are 18X
aabeatoa fiber becauae, on average, aabeetoa makes up about 18% of the raw
materials by weight (aee Section 7.2). We alao aaaumed, for the calculation
below, that the clarifiera which aettle the auapended aolida are about 94X
efficient (Carton, 1974). The efficiency of induatrial clarlfiere, with
reapact to aabeatoa particlea, ia not available. The 94X figure previoualy
quoted relatea to groaa auapended aolida. Aabeatoa may not behave in the same
faahion aa groaa auapandad solidsj therefore, the uae of the 94X efficiency in
the calculation may be queationabla. From Table 7.1, about 900 thouaand tons
of A-C pipe product are annually produced. Therefore!
900,000 ton product x 6.3 Ib solids y 0.18 Ib asbestos Y
yr ton product* 1.0 Ib aolida *
.94 eff. • 9.6 X 103lb aebeatoa
y*
ort 480 tone aabeatoa aettled by clarifiers
y*
In general, moat of tha auapandad aolida collected from aettling in clarifiera
are loaded onto trucka or other tranaport unite and hauled away to landfillat
121
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Capco and Johns-Manville are examples of manufacturers who follow this practice
(Stewart et_ al_., 1976). Landfills are usually, but not always, located on
company grounds. The asbestos fibers in these solid wastes are covered with
cement and can form very hard concretions (Carton, 1974). Stewart e£ al.
(1976) noted, in their asbestos fiber concentration analysis of water effluents
from A-C systems, that a high percentage of fibers were encrusted with a cementa-
tion product. It is therefore probable that the asbestos fibers in this solid
clarifier waste are tightly bound in a cement matrix which could make further
release of asbestos fibers very difficult, especially when buried in a land-
fill.
The water effluent from the clarifiers also contains asbestos fiber;
the quantity of asbestos released via this source has been estimated by two
separate methods. First, the water effluent from the clarifiers in a typical
plant contains about 0.38 Ib suspended solids per ton of product produced
(Carton, 1974). However, four of five pipe manufacturers who were field tested
by Stewart et al. (1976) had begun recycling this wastewater rather than re-
leasing it. These were some of the larger manufacturers; it is doubtful if a
majority of the smaller manufacturers are recycling at this time. There is no
current data available to indicate what percentage of the industrywide effluent
is recycled. Therefore, we arbitrarily assumed that 60% of the total pipe
production is now utilizing water recycling and that the remaining 40% is using
standard clarification; using this assumption, about 12.5 tons asbestos per
year are released in water effluents from A-C pipe plants:
900,000 ton product 0.38 Ib solid „ 0.18 Ib asbestos x 40% release
yr ton product Ib solid
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The second method for estimating asbestos release in water effluents
is based upon monitoring data of asbestos concentrations. Lawrence and Zimmerman
(1977) found that the asbestos concentration of process wastewater which has
9 10
undergone sedimentation at an asbestos-cement processing plant is 10 -10
fibers per liter. The total water effluent discharge from A-C pipe production
Q
is estimated at about 12 x 10 gal/yr .
g
(SRC estimate: 900,000 ton product 1350 gal average* » 12 x 10 gal/yr)
yr ton product
3
Note that 10 asbestos fibers equals one nanogram (Bruckman and Rubino, 1975).
Using a 10 fiber per liter concentration, the following computation can be
made:
10 fibers 10"9 grains 12 x 108 gal discharge 3.785 liter
liter 10-* fibers yr * gal
X ^x release = 20 ton
9 x 10^ grams yr
9
The same computation using 10 fibers per liter yields 2 tons asbestos release
via water effluent per year. The average of 20 tons per year and 2 tons per
year (11 tons/yr) is in close agreement with the first method which resulted in
a calculated value of 12.5 tons per year. These values are dependent upon the
arbitrary assumption of a 40% release.
7.4 Asbestos Release from the Use of A-C Pipe
•' t*\*f
Three studies which have been conducted to determine the levels of
asbestos released from the use of A-C pipe in water transport are a Johns-
Manville Research Center study (reported in Kuschner et_ al. , 1974) , and studies
by Hallenbeck e£ al. (1977), by Buelow et^ al. (1977), and by Craun e£ al.
(1977). The results of these studies indicate that the amounts of asbestos
released during use are small.
*Carton, 1974
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The Johns-Manville Research Center studied two asbestos-cement pipes
different municipal water systems in order to determine if chrysotile
was released. The two pipes, of unspecified ages, were <*r«srin«Hl over a period
of about one year. Paired water samples were taken before and after the water
had flowed through the pipes. On average, the flow of water through the two
pipes increased the asbestos fiber concentration by 0.074 ug/liter and by
0.004 yg/ liter, respectively. This translates to fiber level increases of
7.4 x 10 fibers/liter and 0.4 x 104 fibers/liter, respectively.
In addition, Johns-Manville examined chrysotile loss from a closed
loop system of A-C pipe under laboratory conditions. The results Indicated
9
that an average of 21.9 x 10 gallons of water are required to release one gram
of fibers.
Ballenbeck e£ al. (1977) studied fifteen A-C pipes of various ages,
lengths, and diameters for possible release of cbrysotile asbestos under field
conditions. The pipes were located in northeast Illinois. Paired water samples
were taken froa water before and after it flowed through the pipes. The water
samples were analyzed for chrysotile by transmission electron microscopy.
Chrysotile was identified on the basis of morphology and electron diffraction
pattern. Under the conditions and limitations of this study, no significant
release of chrysotile from A-C pipe was observed. On the basis of average
fiber counts, eight "after" samples showed a slight increase in chrysotile, six
showed a slight decrease, and one group of paired samples was the same. On the
basis of average mass data, there were seven Increases and eight decreases.
Hallenbeck also notes that many water systems under actual use may have
a layer of CaCO. coating the interior pipe wall, thus preventing actual contact
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of the water and A-C surface. Hallenbeck hypothesizes that fibers which are
already present in the water may break down in transit and thus create the
appearance of chrysotile release, in tens of fiber count, fro» asbestos-cement
pipe.
Buelow et al. (1977) have conducted, to date, the most complete
evaluation of potential asbestos fiber release from A-C pipe use with a field
examination of potable water supplies from six different utilities having
various water qualities and using A-C pipe. To determine the possible release
of asbestos fibers from the pipe walls, samples of water as it entered the pipe
and after flowing through the pipe were examined under an electron microscope.
The quality of the water of each of the six utilities' water supply was deter-
mined by a combination of pH, alkalinity, and calcium hardness, which produced
an Aggressive Indices (A.I) in accordance with standards established by the
American Water Works Association (AWVA, 1975). The Aggressive Indices are
simply a definition of the chemical aggressiveness of the water.
The evaluation of the six water supplies, which covered varying
geographical areas of the U.S., produced the following results. Mater of a
non-aggressive or non-corrosive quality produced little or no increases in
fiber levels after transport through A-C pipe. However, significant increases
in fiber levels were produced when water of an aggressive nature was trans-
ported through A-C pipe. Fiber level increases were monitored in the order of
10-10 fibers per liter. One increase of 10 fibers per liter was noted.
Buelow e£ al. (1977) noted that the pH of aggressive water increases during
flow through A-C pipe as a result of the water dissolving the cement out of the
pipe. The dissolution of the cement causes deterioration of the pipe and the
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release of asbestos fibers. As the water is exposed to more and more of the
pipe, the increase in pH and calcium cause the water to become less aggressive.
Specimens of A-C pipe cut from aggressive water supplies showed the above
described patterns of attack on the pipe.
The deterioration of A-C pipe from the most aggressive water system
analyzed by Buelow (Pensacola, Fla.) resulted in clogged water meters, problems
at coin-operated laundries, and collection of visible fibers in kitchen faucet
strainers.
Craun et al. (1977) have examined potable water in Connecticut for
asbestos concentrations in water flowing through A-C pipe. They were attempt-
ing to investigate the use of A-C pipe for public water supplies and the inci-
dence of gastrointestinal cancer. Based upon their sampling results, it was
concluded that the population served by public water systems not using A-C pipe
was not exposed to significant amounts of naturally occurring asbestos in
water. As for the population utilizing ArC pipe for water supplies, Craun et_
al. (1977) have initially reported that the use of A-C pipe probably has not
been responsible for excess gastrointestinal cancers. Nineteen samples were
analyzed from distribution systems after water had passed through various
lengths of A-C pipe. Chrysotile fiber counts ranged from below detectable
limits (10,000 fibers/liters) to 700,000 fibers/liter. Some amphiboles were
detected; concentrations were below 50,000 fibers/liter.
Several points should be made with regard to the above studies.
First, the amount of data which has been generated is actually quite small.
Only a very small percentage of the A-C pipe currently in service has been
monitored for potential fiber release. Also, if chemical aggressiveness is
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the major factor contributing to fiber release from A-C pipe use, then it is
difficult to estimate what percentage of water supply systems may potentially
be undergoing deterioration because there is currently no data available by
which to make such estimations. In addition, only the studies of Buelow
et^ al. (1977) and Craun ^t al. (1977) quantitatively monitored for amphibole
varieties of asbestos; Johns-Manville and Hallenbeck et al. (1977) were con-
cerned only with chyrsotile. Also, there has been no monitoring of A-C sewer
pipe use for potential fiber release. It would seem possible that potentially
corrosive or aggressive liquids may undergo disposal through A-C pipes. Some
monitoring of A-C sewer pipe wastes for fiber releases appears to be very
desirable.
However, from the results of the available studies, it may be assumed
that use of asbestos-cement pipe for water transport does not seem to contri-
bute any large amounts of asbestos fibers into the general environment. When
compared to the quantitative asbestos release from the use of brake linings,
or asbestos release from milling, mining, and manufacturing, the use of A-C
pipe probably contributes very little into the total environmental release.
What is more important, however, is the fact that A-C pipe is used
for potable water supplies. Considering this application, small releases of
asbestos fiber may very well be important.
A number of investigators have identified and measured asbestos
fibers in drinking water supplies (Cooper and Murchio, 1974; Kay, 1974; Cook
et^ al., 1974; Cunningham and Pontefract, 1971 and 1973; Stewart e_t ajL., 1976;
McMillan et al., 1977; Flickinger and Standridge, 1976). However, much of the
data generated by these investigators was samplings from source supplies and
did not include any use of A-C pipe. Levels commonly found in drinking water
127
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supplies ranged from 10 to 10 fibers per liter. These levels are much
higher than the average increases in fiber content suggested by the studies of
Johns-Manville in their testing of A-C pipe but are in line with fiber level
increases determined by Buelow e£ ad. (1977) for very aggressive water.
"Pick-up of asbestos in water that flows through asbestos-cement pipe is very
small, and, frequently, many source waters contain more asbestos fiber than
does water that flows from asbestos-cement pipes" (Olson, 1974).
Two related points to consider are the following: (1) chrysotile
asbestos was found in Chicago rainwater at a level of 10 to 10 fibers per
liter (Hallenbeck e£ jja., 1977), and (2) levels of 10 fibers per liter were
detected in Ottawa melted snow samples (Cunningham and Fontefract, 1971).
The consideration of a potential health problem from drinking water
containing these levels of asbestos fibers is beyond the scope of this report.
Under certain conditions, it may be possible for asbestos fibers in
water to become airborne. For example, certain types of commercial and resi-
dential humidifiers operate on the principle of atomizing water into forced
heating air. If it is assumed that the water supply to this type of humidifier
contains asbestos, it may be possible that the fibers are emitted into room en-
closures through heating ducts. The following hypothetical calculation attempts
to estimate the levels of asbestos which may be added to indoor air as a result
of humidifiers using water containing asbestos. As noted above, levels of
asbestos monitored in water supplies have ranged from 10 to as high as
10 fibers/liter; also, aggressive waters can cause A-C pipe to raise asbestos
levels to the same ranges. For the purposes of this calculation, it is assumed
that the asbestos water concentration is 10 fibers/liter. It is assumed that
an atomizing humidifier is being used by a homeowner, whose house contains
128
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3 3
roughly 400 m (14,000 ft ), and is connected to the central heating system.
The humidifier injects one liter of water, containing 10 fibers/liter, into
the heating system each hour. Therefore, during the course of one day, the
asbestos air concentration of the house could theoretically be raised:
24 ^ Xlber8/hr - 6 X 105 fibers/m3 - 0.6 fibers/cm3 - 600 ng/m3
This calculation is completely theoretical and is not based upon any indoor air
monitoring. Additionally, it does not consider any recycle ventilation through
air filters. It may, however, deserve some consideration.
7.5 Alternatives to A-C Pipe
A-C pipe is principally used for water distribution and sewer systems
In the first application it competes primarily with PVC, cast iron, and steel
pipe; in the second application it competes primarily with vitrified clay,
concrete, cast iron, and PVC pipe. Speaking in general terms, asbestos-cement
is one of the least costly pipe materials. Only locally produced clay and
concrete pipe is less expensive in all size ranges. Cast iron and steel are
appreciably more expensive than A-C pipe in all size ranges. In general, A-C
pipe has a price advantage of about 10% over PVC pipe in most sizes (Lawless,
1977). However, the price advantage can shift to PVC in some larger size
applications.
The choice of pipe material is commonly determined by its specific
application and its cost effectiveness in this application. For example, the
various types of sewer pipe have different flow characteristics and corrosion
resistance. The elevation gradient and type of fluid used in the sewer can
determine which pipe material will be least costly for that application. One
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type of pipe may require a slightly larger diameter to handle the required
flow, and thereby becomes more costly to install.
A-C pipe is primarily used in water supply where the competitive pipe
materials are PVC, cast iron, and steel. When installed in underground appli-
cations, A-C has an advantage over cast iron and steel in that it rarely
corrodes from the outside. As a matter of fact, cement products are commonly
known to become structurally stronger after being left underground for a period
of time (Lawless, 1977). On the other hand, cast iron and steel begin to
corrode from the moment they are placed in the ground. They rust, scale, and
need cathodic protection. However, cast iron and steel are very old and
proven water supply materials and thereby command a healthy percentage of the
water supply market.
The new-comer to the market is PVC pipe. For water supply purposes,
PVC is estimated to have penetrated into 20-30% of the total market (Frey,
1976). PVC is also penetrating into all other pipe market applications.
Future growth in the production of PVC pipe has been estimated to be as high
as 15-20% per year (Frey, 1976). One application in which PVC is replacing A-
C pipe is in large, rural water mains (Gresham, 1977). In many of these rural
applications the pipe is not required to meet fire-code or AWWA strength
standards. This enables a PVC pipe to be produced with a thinner wall and,
thereby, a cheaper cost than can be accomplished with a corresponding A-C
pipe.
Asbestos-cement pipe and PVC pipe are strong market competitors.
What is interesting is the fact that the Johns-Manville Corp. and Certain-Teed
Corp. are two of the largest manufacturers of both products. From Table 7.2 it
can be seen that Johns-Manville and Certain-Teed control a very sizeable
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portion of the A-C pipe market. Frey (1976) lists Johns-Manville and Certain-
Teed as two of the three largest producers of PVC pipe, each having extrusion
capacities of 200-300 million Ibs. per year; Johns-Manville is listed as the
largest in the U.S. Johns-Manville has 12 extrusion plants, while Certain-
Teed has six. In 1975, an estimated 1,020 million Ibs. of PVC were consumed
in pipe production.
PVC has long been resisted by plumbers' unions and cast iron pipe
interests (Frey, 1976). However, market fundamentals, such as cost, demand,
and satisfactory performance, favor continued strong expansion of PVC pipe.
"According to industry observers, leading in the expected continued expansion
of PVC pipe and conduit applications will be low-pressure pipe, particularly
large diameter water pipe (12 inches and larger), and sewer pipe. Other end
uses also expected to continue to grow include telephone conduit and resi-
dential hot-water pipe made from post-chlorinated PVC" (Frey, 1976).
Disregarding cost, A-C pipe appears to be completely replaceable by
alternative pipe materials.
7.5.1 Fiber Replacement in Cement
Work has been done by many companies to find a fiber replacement
for the asbestos fiber in A-C pipe. To date, no fiber has been found which can
duplicate or exceed asbestos's strength, resistance, and other characteristics
when applied to a cement matrix (Jackson, 1977; Lawless, 1977). Types of
fibers experimented with have included fiberglas, glass, metallic, graphite,
and various natural fibers.
Fiberglas fibers have proven unuseable in that fiberglas is not
alkali-resistant. In an alkali-type matrix such as cement, the fibers are
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simply dissolved away in time (Lawless, 1977). Relatively new alkali-resis-
tant glass fibers are now being experimented with and are showing potential
promise as an asbestos fiber replacement in cement. However, within the cost
framework of asbestos fibers and A-C pipe, there is no fiber which can replace
asbestos at this time (Jackson, 1977).
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8.0 ASBESTOS-CEMENT SHEET
Asbestos-cement sheet is a flat or corrugated cement product, using
asbestos fiber as a reinforcing agent, that is widely used in construction
applications such as roofing and siding for both industrial and* residential
buildings. It is also used in the manufacture of heaters, boilers, vaults and
safes, electrical equipment mounting panels, welding shields, and many other
applications requiring a non-combustible or heat-resistant sheet (Daly et al.,
1976).
The corrugated sheet is used primarily in industrial applications as roof-
ing or siding or in warehouse construction for phosphate fertilizers or other
corrosives. The flat sheet has a variety of construction uses. Currently, one
of its larger uses is as a substrate for curtain walls in building construction;
in this application, the building contractor applies an epoxy-type finish to the
sheet before attaching it to the building exterior. Asbestos-cement sheet is
used in its various applications primarily due to its resistance to corrosion,
mildew, etc. as well as its fire code rating. It is not intended to be used as
weather insulation (Breiner, 1977).
8.1 Use Quantities, Shipment Values & Industrial Firms
U.S. demand for asbestos in A-C sheet products has ranged from 23 to
95 thousand short tons annually during the 1967-1976 period; in 1976, about
23 thousand tons of asbestos were consumed in A-C sheet (Tables 4.9 and 4.10,
p. 46). According to the 1976 figures, about 3.1% of the total U.S. market for
asbestos was consumed in the production of A-C sheet; this 3.1% figure is down
sharply from the 11.2% and 7.2% market shares in 1974 and 1975, respectively.
A large portion of the apparent decrease from 1974 to 1976 is attributable to
133
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a change in reporting definitions; that is, that portion of A-C sheet produced
for roofing purposes is listed, in 1976, under roofing and not under A-C sheet.
In recent years, the growth of the market for A-C sheet in the U.S.
has lagged behind that of the construction industry in general, amounting to
only a few percent per year (Igwe, 1974). At this time, the market for corrugated
sheet is stable and is projected to remain that way, however, the flat sheet
market has fallen somewhat and small decreases in the future are foreseen
(Breiner, 1977). A combination of competitive pressures from alternative
products and concern for exposure to asbestos fibers by contractors are the main
reasons for the slight market decreases.
Table 8.1 lists the shipment values of A-C sheet. Unfortunately,
quantities such as poundages are not given by the Census Bureau. Igwe (1974)
reports that about 400,000 tons of A-C sheet were produced in 1973. However,
based upon the classification system used in 1976, approximately 125,000 tons
of A-C sheet were produced in 1976 for purposes other than roofing (SRC estimate).
The A-C sheet made for roofing is considered in section 9.0 (Asbestos Roofing);
this is especially important to note when considering environmental releases.
Table 8.2 lists the major manufacturers of A-C sheet along with their
respective locations. Data for recent sales by the individual locations is not
available; most of the locations have diversified product lines.
8.2 Manufacturing Process Technology
Flow diagrams and brief descriptions of processes used to produce
A-C sheet are included in section 9.2, and will therefore not be detailed here.
The manufacturing process for A-C sheet is quite similar to the process used to
produce A-C pipe, especially in terms of environmental releases and their treat-
ment. This permits an identical approach to estimating quantities of asbestos
release as was described for A-C pipe.
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Table 8.1 Shipment Values of Asbestos-Cement Sheets
(U.S. Bureau of the Census, 1972 Census of Manufacturers)
Total Product Shipments, including interplant transfers
(millions of dollars)
SIC Product Code Product 1972 1967
32927 41 Flat sheets and wallboard 20.7 15.2
32927 51 Corrugated sheets 5 3.5
*
SRC estimate.
-------
Table 8.2 Major Manufacturers of A-C Sheet
(Carton, 1974 modified by several
industrial sources)
Manufacturer
Johns-Manville
GAF Corp.
National Gypsum
Celotex Corp.
Nicolet Ind.
Location
Waukegan, 111.
Nashua, N.H.
Mobile, Ala.
St. Louis, Mo.
South Bound Brook, N.J.
New Orleans, La.
Cincinnati. Oh.
Ambler, Pa.
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Nearly all of the asbestos presently used in A-C sheet is chrysotile;
a very small amount of amosite and anthophyllite is also used (Table 4.10, p. 46)
The asbestos content of the A-C sheet product can vary depending upon intended
use. A-C sheet products manufactured by Johns-Manville contain 30-40% asbestos;
therefore, it will be assumed that A-C sheet contains an average content of 35%
asbestos. This figure is used in estimating releases from process wastewaters.
8.3 Quantities of Asbestos Released to the Environment from Manufacture
Listed below in Table 8.3 are the estimated quantities of asbestos
released to the environment from A-C sheet manufacture. The estimates in
Table 8.3 are intended to estimate a general magnitude of release only.
Table 8.3 Estimated Annual Environmental Releases of Asbestos
from A-C Sheet Manufacture (SRC Estimates)
Quantity
(short tons) Comment
To Waste Dump or Landfill:
rejected sheet & scrap
baghouse fines
process wastewater solids
To Water:
from process wastewater
To Air:
from baghouse emissions
1525
105
74
1.9
0.01 - 1.5
fibers bound
free-fibers
fibers bound
fibers coated
free-fibers
in cement matrix
in cement matrix
with cement
The estimates in Table 8.3 were derived by methods which are explained in
the following subsections.
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8.3.1 Release From Baghouses and Rejected Sheet and Scrap
As detailed in section 7.3.1, Harwood and Ase (1977) have
estimated that 5-10% of the product material, for A-C products in general, is
dumped as scrap, of which 10% is fine dust from baghouse collection and 90% is
coarse scrap from trimmings and breakage and from products which have failed
quality assurance testing. If it is assumed that the A-C sheet product is
about 35% asbestos fibers, then about 66,000 tons of A-C sheet product were
produced in 1976 based upon the asbestos consumption of 23,000 tons listed in
Table 4.9 (p. 46). As mentioned earlier, this is the A-C sheet production for
purposes other than roofing. Approximately an equal amount of sheet was
produced for roofing; therefore, if the estimates in Table 8.3 are doubled,
then the total releases from all A-C sheet manufacture are derived.
Using the Harwood and Ase (1977) relationships detailed in
section 7.3.1, we can calculate the releases from rejected sheet and scrap and
baghouse fines as shown in Table 8.3.
The baghouse emissions can be estimated by using the Siebert
ej^ _al. (1976) figure of 99.99% efficiency of baghouses to yield an estimate of
0.01 tons per year. However, using the factor of 1.34 Ib. asbestos fibers
emitted per year per 100 CFM rating and assumptions of a plant volume of 10
cubic feet and 15 air changes per hour, as detailed in section 7.3.1, it can
be calculated that about 1.5 tons of fibers are emitted annually by 8 plants.
f
The discrepancy between the two estimates is large. As mentioned earlier in
section 7.3.1, the 1.34 Ib. emission factor is a worst possible estimate;
i
therefore, the result of 1.5 tons of fiber emission may be on the high side.
In addition, it must be remembered that most A-C sheet production takes place
138
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in multi-asbestos product plants which feed a common baghouse, so estimates
are only partial to total emissions.
8.3.2 Release From Process Wastewaters
The raw water discharge from a typical manufacturing process
contains about 13 Ibs. of suspended solids per ton of product produced (Carton,
1974). For A-C sheet production we assumed that the suspended solids are
approximately 18% asbestos fiber, because roughly 18% of the raw material
composition is asbestos by weight. We also assumed that the clarifiers which
settle the suspended solids are 96% efficient (Carton, 1974), and that about
125,000 tons of A-C sheet are annually produced. Therefore:
66,060 tons product x 13 'lb. solids 0.18 Ib. asbestos .96 eff.
year ton produce lb. solid
1.48 X 10 lb asbestos OR 74 tons asbestos settled by clarifiers
year — year
Clarifier efficiency, with respect to asbestos particles only, has never been
determined. The 96% efficiency factor above relates to gross solids. Settling
characteristics for asbestos may differ and the use of the 96% figure may be
questionable. It is used for lack of a better figure. In general, the solids
collected from settling in clarifiers are disposed of in landfills. As was
the case for A-C pipe, the asbestos fibers are covered with cement and become
very solid concretions.
The water which is discharged from the clarifiers also contains
asbestos fiber; the quantity of asbestos released via this source has been
estimated by two separate methods. First, the water effluent from the clari-
fiers in a typical plant contains about 0.45 lb. suspended solids per ton of
product produced (Carton, 1974). However, four of five A-C sheet producers
139
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field tested by Stewart et^ al., (1976) had achieved varying degrees of recycling
of the process wastewater. There is no current data available to indicate what
percentage of the industry-wide effluent is recycled. Therefore, we assumed
that about 30% of the total sheet production is now utilizing water recycling
and that the remaining 70% is utilizing standard clarification. Using these
assumptions, about 1.9 tons of asbestos per year are released in water effluents
from A-C sheet plants
66,000 ton product 0.45 Ib. solids .. 0.18 Ib. asbestos ._„ .
year ton pdt. Ib. solids
The second method for estimating asbestos release in water
effluents is based upon monitoring data of asbestos concentrations. Lawrence
and Zimmerman (1977) found that the asbestos concentration of process waste-
water which has undergone sedimentation at an asbestos-cement processing plant
9 10
is 10 - 10 fibers per liter. The total water effluent discharge from A-C
8 /
sheet production is estimated to be 1.19 x 10 gal/yrfSRC estimate:
66,000 ton product „ 1800 gal discharge |
year ton product I.
Using a 10 fiber per liter concentration, the following computation can be made:
**
in Q A
10AU fibers 10"* grams 1.19 x 10 gal effluent 3.785 liter
liter A 1fl3 ... year A gal
10 fibers ' e
x 1 ton x 70% release * 3.5 tons
9 x 10 grams year
9
A similar calculation using 10 fibers/liters yields about .35 ton asbestos
release via water effluent per year. The average of 3.5 tons/yr and .35 ton/yr
(1.95 tons/yr) is in close agreement with the first method which resulted in a
calculated value of 1.9 tons/yr. These values are dependent upon the assumption
of a 70% release.
M Carton (1974)
See section 7.3.1 for discussion of this conversion factor.
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8.4 Asbestos Release from Use of A-C Sheet
In the United States, asbestos-cement sheets are used principally for
industrial buildings (particularly fertilizer plants and other applications
where corrosion is a problem), warehouses, and in similar cost-sensitive markets.
It is also used to a limited degree as a siding in the residential market (Igwe,
1974).
The potential release of asbestos fibers from A-C sheet used in the
roofing industry is discussed in section 9.4. There it was estimated that the
greatest potential for release of fibers was involved with the effects of weather.
Similar inferences can be drawn for A-C sheet siding which is exposed to the
weather. However, it should be pointed out that there is no available monitoring
data by which firm predictions can be made to estimate release quantities from
weathering or corrosive effects.
It would seem quite possible that A-C sheet which is not exposed to
weathering effects, corrosion, or damaging mechanical forces would release vir-
tually no fibers because the fibers are tightly bound in the cement matrix.
Installation of A-C sheet is one mechanical force which may permit release of
fibers; demolition of buildings containing A-C sheet is another.
Installation of A-C products may require some sort of field fabrication,
such as sawing, trimming, drilling, or grinding, which would release asbestos
fibers. However, such fabrication to meet customer specifications is usually
done by central fabricating shops (EPA, 1974). The flat asbestos sheets used
in homes, barns, or other inexpensive construction are usually installed with
fasteners or nails and require little drilling. The EPA (1974) found that the
asbestos-cement products that were field-fabricated were usually cut with knives
141
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or saws equipped with dust-collection devices, and holes were drilled with drills
equipped with dust-collection devices. Accordingly, the EPA (1974) determined
that the field fabrication of asbestos products, other than insulating (friable)
products, is not a major source of asbestos emissions to the air.
The amount of asbestos-containing dust generated by central shops that
fabricate asbestos-cement building products was estimated to be about 200 Ibs./week
(EPA, 1974). This is an annual rate of 10,400 Ibs.; if we assume an asbestos
content of 18%, then slightly less than one ton of asbestos fibers is annually
generated by these fabrication shops. It is assumed that disposal of these
wastes is to dumps or landfills.
The life-expectancy of an A-C sheet product is probably in the range
of 15 to 25 years. After this time it will be replaced with a new material. If
it is assumed that about 75% of the annual production is for replacement-type
purposes, then perhaps 187,000 tons of A-C sheet products are replaced each year
containing about 34,000 tons of asbestos. This includes A-C sheet for both
roofing and other uses and does not consider any weathering effects. Effects
of weather are discussed in section .9.4. It can be further assumed that most
of the worn-out or replaced sheet is disposed of in waste dumps or landfills.
8.5 Alternative Products, to A-C Sheet
Asbestos-cement sheet refers to a broad family of corrugated and flat
board products used in the construction industry for roofing and siding. It
competes principally with masonry, galvanized steel, aluminum sheet, plastics,
wood and asphalt (Breiner, 1977; Igwe, 1974). A-C sheet is generally more expen-
sive than corrugated steel, competitive with aluminum sheets, and less expensive
than conventional concrete blocks and built-up roofing.
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One of the main selling advantages of A-C sheet, especially in indus-
trial applications, is its resistance to rot, corrosion, and mildewing (Breiner,
1977). Another advantage is, of course, its fire resistance. However, there
is virtually no application in which A-C sheet could not be substituted for by
current market alternatives, although the cost may be somewhat higher if alter-
natives are used.
Replacement for the asbestos fibers, in the A-C sheet products, by
some alternative fiber or filler, has been and is being attempted by the major
manufacturers. These potential alternatives include fiberglas, glass, carbon
fibers, and various natural, synthetic, and mineral fibers. None of these
potential alternatives are as good as asbestos in overall characteristics and,
additionally, many of the alternatives are more costly. Considering these
factors there is no market for an alternative A-C sheet product utilizing
fibers other than asbestos.
Cost comparisons between A-C sheet and its competitive products, such
as aluminum sheet, steel, etc., have not been included because of the many
varieties and thicknesses of materials which are available. A cost comparison
would be meaningful only for specific applications.
143
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9.0 ASBESTOS IN THE ROOFING INDUSTRY
The roofing industry consumed approximately one-third the total asbestos
fiber consumed in the U.S. in 1976. The quantity, 253,000 tons as now classi-
fied, is the largest single use for asbestos (Table 4.9, p. 46).
By the former U.S. Bureau of Mines classification the annual use had been
steady near 80,000 tons since 1967 (Clifton, 1974, 1976). The dramatic in-
crease in the 1976 figure is not attributable, however, to a big rise in the
asbestos roofing market, but rather to a probable change in reporting classi-
fication. Industry spokesmen indicate that the asbestos roofing market is
undergoing static growth with foreseeable small decreases and that the large
1976 consumption figure probably includes all asbestos paper, A-C sheet, and
asbestos coatings used by the roofing industry. Corresponding decreases in the
consumption figures for paper, sheets, and coatings are noted (Table 4.9, p.
46), although not in sufficient quantities to make up the 253 thousand ton
figure. It should be noted that in a survey of the asbestos Industry, Daly et
al. (1976) calculated that about 38% of the total asbestos consumption is
incorporated in asbestos paper; based on a total consumption of 725,000 tons
in 1976, this would amount to 276,000 tons. Since most of the asbestos roofing
products produced involve coating asbestos paper with asphalt, etc., the 1976
Bureau of Mines' figure for asbestos consumption in the roofing industry
(253,000 tons) may reflect close agreement with the Daly survey. Therefore, we
feel that the 1976 figures published by the Bureau of the Mines are probably
accurate figures, and, therefore, these figures are used throughout this report
in estimating fiber releases. Igwe (1974) estimates that asbestos roofing
makes up about 2% of the total roofing industry.
144
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Roofing products being exposed continuously to weather deteriorate slowly,
and their resistance to atmospheric conditions is reduced. The material must
be eventually replaced and scrapped. Asbestos fiber may thereby be released
during these wear and replacement stages, finally reaching the environment in
the scrap, in landfills or trash dumps, in water run off from rain and snow, or
to some lesser extent as airborne dust. In addition, asbestos fiber can poten-
tially be lost to the environment in fabricating the fiber into the roofing
products.
Section 9 will cover specifically these losses of roofing asbestos fiber
to the environment and provide approximations of the quantities released.
9.1 Asbestos Roofing Products
The principal roofing products containing asbestos as an essential
ingredient are asphalt roofing felt and papers, asbestos-cement roofing sheet
and shingles, and asbestos-asphalt paints, coatings, and sealants. All are
well established products that have been made since the early 1900's and before.
The asbestos fiber used in roofing products is essentially chrysotile,
with about 99% as the finest grade 7 milled mineral (Clifton, 1976). Approxi-
mately 85% of the milled product was imported from Canada, as based on the
total U.S. consumption. Two mines in the eastern U.S. and four in California
and Arizona produced the balance (section 5.1).
Table 9.1 lists manufacturers and locations of asbestos roofing
products. The plant at Savannah makes only roofing. All others are multi-
asbestos product operations.
Asbestos is added to roofing materials to improve and stabilize
strength, to increase resistance to corrosion and rot, as well as to give
145
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Table 9.1 Major U.S. Manufacturers of Asbestos Roofing
(Carton, 1974; Igwe, 1974)
Manufacturer
Johns-Manville
GAF Corp.
Celotex Corp.
(Jim Walter Corp.)
Location
Waukegan, 111.
Marrero, La.
Manville, N.J.
Fort Worth, Tex.
Savannah, Ga.
Los Angeles, Cal.
Millis, Mass.
South Bound Brook, N.J.
Linden, N.J.
Cincinnati, Ohio
Houston, Tex.
Memphis, Tenn.
146
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insulating and fire resisting advantages. The high tensile strength of the
fine asbestos fiber reinforces the asphalt and cement matrices. The dimensions
of the product are maintained and the disintegration of alternative organic
reinforcement avoided (Daly et al., 1976).
The available shipping values and quantities of asbestos roofing
materials are given in Table 9.2. It is estimated that the 1977 value of
products listed in Table 9.2 would be about $70 million (SRC estimate). This
represents a sales value of approximately $250 per ton of asbestos contained in
the roofing products.
It is judged that since there has been no significant change in
recent total consumption of asbestos roofing materials that the relations
presented in Table 9.2 are close approximations to current consumption.
9.2 Manufacturing Technology
Asbestos roofing products are made by three major processes. First,
the asbestos paper used for the asbestos asphalt roofing felt and paper is made
by the usual paper making process. Second, this asbestos paper is impregnated
with asphalt by dipping and coating procedures. Third, asbestos-cement flat,
corrugated sheet and shingles are made by similar methods as used in asbestos-
cement pipe production. Bituminous roofing paint and coating products are made
simply by batch mixing asbestos fiber into mastic mixtures.
Dry milled asbestos used for the above processes is received in paper
bags which are dumped by manual or semi-manual means into storage facilities or
directly into preparatory mixing equipment. Extreme care is required to mini-
mize dust that these operations produce. Hoods and vacuum ventillating systems
are required.
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Table 9.2 Shipment Values and Quantities of Asbestos Roofing Materials
(U.S. Bureau of the Census, 1972)
SIC Product
Code
Product
Total Product Shipments, including interplant transfers
1972 1967
Quantity Value Quantity Value
(million sq.) ($ million) (million sq.) ($ million)
32924 —
32924 11
32924 51
32924 00
Asbestos Cement Shingles & Clapboard
Siding Shingles & Clapboard
Roofing Shingles
A-C Shingles & Clapboard, n.s.k.
2°-8
24.0
00
32927 81
Asbestos Felts:
Roofing, asphalt or tar saturated
7.5
23.2
11.2
SRC Estimation calculated by apprdximation from Value and current (1977) price of $20 per 4 square roll
with 50% inflation allowance.
-------
The asbestos paper is made by essentially the same process as used
for cellulosic papers. The fiber is pulped with water into a 1-3% slurry. Dry
mixing of the fiber and additives may precede the wet pulping. The stock is
fed to either a Fourdrinier paper machine or to a multicylinder type machine
(Whitney e± al., 1967; Carton, 1974). In both machines, paper forms on screen
surfaces as the pulp is drawn through. The wet mat is conveyed to steam heated
drying cylinders and rolls. After drying, the paper is cut into sheets and
collected on rolls. The excess water after fiber removal is recirculated to
the pulping step, except for a purge stream that is withdrawn for purification
or waste. The purge is the major effluent.
The above felt or paper is then saturated with asphalt or coal tar in
a series of steps as shown in Figure 9-1. The first step is the "dry looper"
(Berry, 1968) from which the felt is fed to the succeeding steps. In the
first, the felt passes through a saturating tank containing melted asphalt at
450-500°F. Next, it is passed to the "wet looper" where the excess asphalt
drains off as the saturated sheet cools. The felt is then coated with asphalt
at 350-400°F. Minerals may also be added to the surface. The felt is next
cooled to 225-275°F on water coated rolls and finally to 100°F by direct water
sprays in the "finish looper". The product is finally finished into rolls on a
mandrel, cut and trimmed, and wrapped for shipment.
The cooling water may be circulated through a cooling pond or tower
or wasted.
For built-up roof felt, the paper is not coated. The felt for this
case is field coated by mopping hot asphalt or pitch onto the felt as it is
laid in plies at the site. Coated or prepared roofing paper is simply laid in
149
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ASBESTOS PAPER
STORAGE
HOT COAL TAR
OR ASPHALT4"
SATURATION
STEAM
COOLING
WATER
HEAT TREATMENT
UNCOATEO
ROOFING
COATING
COOLING
WATER
COOLING
CUTTING
ROLLING
PACKAGING
STORAGE
CONSUMER
FUMES
COOLING
WATER
COOLING
WATER
WASTEWATER
Figure 9.1. Asbestos Roofing Manufacturing Operations (Carton, 1974)
150
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plies and cemented together by cold adhesives (Berry, 1968). The amount of
material which may be friable before pitching is not available, but is judged
to be small.
Asbestos-cement sheet and shingles are made by either a dry process
or a wet mechanical process. In the dry process, a dry mixture of fiber,
cement, and additives is distributed uniformly onto a flat conveyor belt,
sprayed with water, and compressed by steel rolls to required thickness (Figure
9-2). The moving sheet is cut into desired sizes or into shingles and finally
steam cured in autoclaves. Water that is used to clean the forming equipment
is normally collected for clarification and either recirculated or wasted. The
settled solid material from the clarifiers is recycled or wasted in dumps or
landfills (Carton, 1974).
In the wet process, Figure 9-3, the asbestos fiber is blended with
cement and additives and mixed with water. The mix is pressed to form the
product, then air or steam cured, and finally finished into sheets, up to 0.10"
thick. The wet mechanical process, Figure 9-4, is similar to the asbestos
cement pipe operation,'Figure 7-1. The water from the forming step is clari-
i
fied and recycled similarly, with the same sludge and wastewater disposal
requirements.
The production of roof coatings, sealants, paints, and undercoatings
consists of mixing asbestos and other additives into an asphalt base (Daly et
al., 1976). Solvents are added to reduce the viscosity - and especially for
spray applications and emulsions. The process is batch. The asbestos fiber is
added to the asphalt mastic mix and dispersed evenly, thereby encasing the
fibers with the asphalt. The mix is pumped to a container filling station.
151
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RAW MATERIALS
STORAGE
PROPORTIONING
DRY MIX
WATER
STEAM
^
1 ROLLING 1
1 CUTTING ^* •" ••
X
1 CURING !"••••••
FINISHING
STORAGE
CONSUMER
WASTEWATER
SOLIDS
CONDENSATE
Figure 9.2. Asbestos-Cement Sheet Manufacturing Operations, Dry Process
(Carton, 1974)
152
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WATER
STEAM
RAW MATERIALS
STORAGE
PROPORTIONING
DRY MIX
WET MIX
PRESS
HARDENING
CURING
WASTEWATER
CONOENSATE
FINISHING [
CONSUMER
Figure 9.3.
Asbestos-Cement Sheet Manufacturing Operations, Wet Process
(Carton, 1974)
153
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WATER
STEAM
RAW MATERIALS
STORAGE
PROPORTIONING
DRY MIX
WET MIX
FORMING
CURING
AIR/AUTOCLAVE
CUTTING
FINISHING
STORAGE
CONSUMER
RECYCLED SOLIDS
RECYCLED WATER
WASTEWATER
CLARIFICATION
(SAVE-ALL)
I
SLUDGE
CONDENSATE
SOLIDS
Figure 9.4. Asbestos-Cement Sheet Manufacturing Operations, Wet Mechanical
Process (Carton, 1974)
154
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The product is packaged in containers ranging from 5 gallon pails to tank
cars. There are a large number of these coating plants. They vary in size,
with about 3 million gallons per year as a maximum.
9.3 Quantities of Asbestos Released to the Environment from Manufacture
Listed in Table 9.3 are the estimated quantities of asbestos released
to the environment from asbestos roofing product manufacture. An attempt has
been made to eliminate overlapping of end-uses; for example, manufacturing
losses from production of asbestos paper and A-C sheet used in roofing products
will be considered in this section while production of these products for uses
other than roofing will be considered in another appropriate section. The
summary at the end of this report will bring appropriate figures together. The
estimates in Table 9.3 were made by methods which are explained below.
These estimates assume emission control techniques outlined fully in EPA (1973)
publication.
9.3.1 Release from A-C Sheet and Shingle Production
First, it is assumed that about 125,000 short tons of A-C sheet
and shingles are annually produced for roofing purposes. Applying the same
release calculation methods as detailed in section 7.3.1, about 2,050 tons of
asbestos are released as rejected product and scrap and about 142 tons of
asbestos are released from baghouse collections. Similarly, using the same
methods detailed in sections 7.3.1 and 8.3.2, the amounts of fiber released in
process wastewaters and baghouse emissions are calculated to yield the results
shown in Table 9.3.
9.3.2 Release from Asbestos Paper Production
The methods for calculating the release of asbestos from process
wastewaters from asbestos paper production are detailed in section 10.3.1 and
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Table 9.3 Estimated Environmental Release of Asbestos from Asbestos Roofing Production
(SRC Estimates)
To Waste, Dump or Landfill:
1) A-C Sheet & Shingle Prodn.
a. rejected product & scrap
b. baghouse fines
c. process wastewater solids
2) From Asbestos Paper Prodn.
a. rejected product & scrap
b. baghouse fines
c. process wastewater solids
& 3) From Paper Coating Operations
°* a. rejected product & scrap
b. baghouse fines
4) From Asphalt Mastic
a. baghouse fines
b. rejected product & scraps
To Water
1) From A-C Sheet & Shingle Prodn.
from process wastewater
2) From Asbestos Paper Prodn.
process wastewater
3) From Paper Coating Operations
from process wastewater
To Air From Baghouse Emissions
1) From A-C Sheet & Shingle Prodn.
2) From Asbestos Paper Prodn.
3) From Paper Coating Operations
4) From Asphalt Mastic
Quantity
(short tons)
1525
105
74
n.a.
968
1961
1900
n.a.
36
180
1.9
38-80
n.a.
0.01-1.5
0.1-2.1
n.a.
.0036-1.0
Comment
fibers in cement matrix
free-fibers or matrix containment
fibers coated with cement
small as it can be recycled
free-fibers
fibers matted together by starch or elastomer
binder, but free-fibers are a definite
possibility
coated asbestos paper
see section 9.3.3
free-fibers which can be recycled
fibers bound in asphalt mastic
fibers coated with cement
free-fibers with some coating of starch or
elastomer binder
probably small, see section 9.3.3
free-fibers
free-fibers
probably small, see section 9.3.3
free-fibers
-------
will, therefore, not be included here. Applying these methods with the assump-
tion that 85% of the asbestos fiber consumed in roofing applications (253,000
tons) is for paper production, then the quantities shown in Table 9.3 can be
directly computed.
Rejected papers, scraps, and trimmings are apparently not
wasted in significant amounts; Carton (1974) states that trimmings, defective
paper, and other waste paper can usually be returned to the beater and repulped
for recycling.
There is no direct monitoring data on which to base estimates
for releases from baghouses used exclusively for asbestos paper production.
However, it may be possible to apply certain relationships to baghouse para-
meters as detailed in section 7.3.1. Harwood and Ase (1977) determined that
about one short ton per day of baghouse fines is collected per 220 short tons
of A-C pipe production; this collection represents about 0.45% of the produc-
tion quantity. Applying this 0.45% figure to asbestos paper production, it can
be determined that about 968 tons of asbestos fibers are collected by baghouses.
Similarly, using the Siebert et^ al. (1976) baghouse efficiency of 99.99%, it
can be calculated that about 0.1 ton of very short asbestos free-fibers is
emitted by these baghouses each year. Also, using the relationship of 1.34 Ibs.
of fibers emitted per year per 100 CFM rating, as developed in section 7.3.1
for baghouses. it can be estimated that perhaps 2.1 tons of fibers may be
emitted by baghouses; however, as explained in section 7.3.1, this figure is
probably too high.
9.3.3 Release from Asphalt and Paper Coating Operations
Most asbestos roofing is made by saturating heavy grades of
asbestos paper with asphalt or coal tar, with the subsequent application of
157
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various surface treatments. The stock paper may be single or multiple layered
and usually contains mineral wool, kraft fibers, and starch, as well as asbestos,
Fiberglas filaments or strands of wire may be embedded between layers for re-
enforcement (Carton, 1974).
Unlike the asbestos operations covered previously, water is not
an integral part in the asphalting or coating operation. Water is used to
cool the roofing after saturation. All plants use non-contact cooling and
some use spray contact cooling. The roofing is largely, but not completely,
inert to water and the contact cooling water becomes a process wastewater
(Carton, 1974). However, monitoring of this wastewater has not been done as
Carton (1974) monitored a roofing plant using non-asbestos paper. It would
seem that releases of asbestos fibers by this operation would be very small in
quantity as the roofing paper has already been coated. Monitoring data are
desirable.
As far as the asbestos fibers are concerned, these coating
operations are really secondary manufacturing steps; that is, the greatest
potential for fiber release has already occurred in the primary manufacturing.
There are no useable monitoring data available for estimating quantities of
baghouse fines or emissions which may occur from coating the asbestos paper.
It would seem, however, that these quantities would be only a small fraction
of the totals estimated for paper production.
Likewise, there are no monitoring data available for estimating
the amount of rejected roofing paper and scraps. Harwood and Ase (1977) have
determined that about 5-10% of asbestos-cement production is scrapped due to
breakage or quality. This figure seems much too high to apply to roofing
paper. An engineering estimate of 1% would seem to be more appropriate;
158
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therefore, about 1,900 tons of asbestos are usually scrapped in roofing paper
rejects. It is assumed that these scraps are disposed of in dumps or land-
fills.
9.3.4 Release from Mastic Asphalt Mix Production
The mixing of asbestos fibers with asphalt to make a mastic mix
useable in roof coatings does not involve the use of any process water. There-
fore, there are obviously no fiber emissions from a process wastewater source.
The primary release of fibers in this overall production prob-
ably occurs during bag opening and initial asphalt mixing (Daly e£ al_., 1976).
After the fibers have been incorporated into the asphalt, release during manu-
facturing is virtually nonexistent.
The change in the Bureau of Mines' asbestos consumption figures
for coatings from 1974 to 1976 was about 18,000 tons (Clifton, 1975, 1977). We
assumed that this is approximately the amount of asbestos used in roof coatings.
However, there are no data available by which to make direct estimations of
baghouse collections and emissions or product rejects. The baghouse estimation
method developed in section 9.3.2 does not appear to be applicable to the
asphalt mastic mix because process steps such as trimming and calendering,
Which contribute fiber to the baghouse, are not done. If we lower the collec-
tion factor to 0.2%, the results obtained are probably more realistic. There-
fore, we can estimate that about 36 tons of asbestos fibers are collected by
baghouses. Applying the Siebert et al. (1976) baghouse efficiency of 99.99%
indicates that .0036 ton or 7.2 Ibs. of fibers are emitted. The alternate
method for predicting baghouse emissions given in section 7.3.1 would estimate
emissions to be on the order of one ton.
159
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Assuming product rejects and scrap total about 1% of production,
then 180 tons of asbestos would be wasted to dumps or landfills.
9.3.5 Overall Considerations
The figures estimated in the previous subsections apply only to
roofing products. There are additional releases involved in the production of
A-C sheet, asbestos paper, and coatings for purposes other than roofing. Those
releases are dealt with in their respective sections. It should also be remem-
bered that these roofing operations are usually located in multi-asbestos
product plants and that the estimations are only partial to the total plant
losses.
An appropriate question which should be asked is, what happens
to asbestos fiber which is released to the environment?
The eventual fate visualized is that the airborne material would
settle, be picked up by rain or melting snow and passed on into streams and
rivers with the waste water effluent, and finally lodge in river and lake
beds, harbors, beaches, and shoals in these various bodies of water. The
buried landfill and trash dump material may be stabilized with accompanying
substances. As mentioned earlier in section 7.3.1, asbestos waste piles are
potential sources of atmospheric fiber emissions.
9.4 Release of Asbestos from Installed Roofing Products
Asbestos roofing products are subject to weathering. Usual life is
15 to 25 years. Weathering results in changes in the asphalt or cement binder
with little loss of asbestos. New roofing may be applied over the old. Tearing
off of the old roofing is done when the old roofing has deteriorated to an extent
to prohibit applications of new build-up or when the roof structure needs repairs
for leaks or rot. The asbestos is therefore principally released with the
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scrapped material when discarded to landfill or trash dump where the scrap is
buried.v It is estimated that the annual quantity of this scrapped asbestos
would be approximately 75% of the total consumption or about 200,000 tons.
Some scrap material may be incinerated during which the asbestos
could possibly be released in the combustion gases or in the incinerater ashes.
Loss with combustion gases should be controlled by scrubbing. If not destroyed
during incineration, the asbestos in the product could be released as the ashes
are used - such as in fertilizing or in making cement blocks. It is not pos-
sible to evaluate possible losses for these alternatives.
It is conceivable that some fraction of the roofing products might
deteriorate in use to smaller particles that would wash away with rain or snow,
or would be fine enough to become airborne. There are no monitoring data
available, however, which have monitored for asbestos release from roofing
materials during use. Most detachments from use of roofing materials are
reported to be as large pieces of asphalt covered material (Fricklas, 1977).
The amounts of asbestos which may become detached in free-fiber form, if any,
are not known.
The following hypothetical calculation is made to estimate a theoreti-
cal magnitude of contamination, from roofing wear, by applying various assump-
tions. The following assumptions are made:
1) the concentration of exposed roofing products and their annual
consumption follows population density;
2) 75% of annual consumption is used as replacement;
3) 0.1% of the asbestos in roofing products is detached from
the product by weathering or other forces in free-fiber form;
4) annual use of asbestos in roofing is 253,000 tons.
161
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Syracuse, with A population o£ IB'J.UOU, is chosen as the example olty. Apply-
ing che above assumptions, Ui*> detachment of asbestos from roofing in Syracuse
would be i
x •" <"'uo"-> x °-001
o.IMini.o.ug_. S.M x io11 §L
AII Hunting chat the daily detachment of aabaatos becomes equally diatributed in
the ambient air up to 1,000 n. above the 25,8 aq. mile area of Syracuse, the
dally emleaion* of aabeatoa would raise the ambient air concentration by IB ng/n3
for static air rlow oonditiona,
Aiaumlng further that the 18 ng/m are waahed from the air by 0.3 inohti
«»r rain (8,5 X 10* lUt»r§/23.H aq, milea), the aabeatoi liter ooncentraclon of the
fallen rain would be roughly 4,3 X 10 fibers/ liter an ahovn below i
8,5 X 108 lltera
4,3 X 10 fibere/liter
The above calculation! are totally hypothetical and are not baaed upon any
monitoring data, However, emiaaiona of aabeatoa fiber* due to weathering may
be a potential Haurce of releaae and warrant 110Id t Ueuk,
Loeaef) during inatallatlon and laying chf material are nut lonaiderad
ID be significant, The aabeatoe flbwra are onuanbd by ttephaU or cement,
Field fabrication of aabeatoa-cement can release Nome duat during fitting and
cutting operational however, theae fabrication* are usually done by central
fabricating shops as explained in section 8,A. The scrap mads by cutting and
fitting is wasted to landfills and dumps,
162
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In aummary, release of aabeetoa from inetalled roofing product!
appcara to bt eeaentlally in the worn out material that ii aorappad - with
eventual fata in landfill and eraah dumpa. Plaid chacka on air during uaeh
dumping, ahraddlng, and inoinaration oparationa eeam to ba indicated, aa wall
aa tha atmoaphara in vary high danaity urban loeationa. Adherence to work
practicaa outlinad in RPA (1970) publication and approvad amendment to Glaan
Air Aot of 1977 ahould ba checked.
9,3 Altarnativaa to Aabaatoa Roofini Product!
Tha main roofing product, aabaatoa aaphalt fait, could ba replaced by
tha plain aaphalt product without aerioua effect!, ainoa tha aabaatoa product
la a email percentage of tha entire application, Tha priea at $20 par roll ia
twice that of plain felt. Whan uaad, the added coat of aabaatoa aaphalt felt
ia juatifiad by ita longer life and repairability and by ita higher fire code
ratingi
Aabaatoi-cement ahaet coating about tha aame per equara foot ia uaad
largely aa roof panela for induatrial building! in place of other more ooatly
conatruction. Replacement by metal or plaatica could be made at an additional
expenditure,
Aibeito! aa an ingredient to roof coating and aealant compound! in
unique in that it adda atability to tha covering, Due to the fineneea or the
aabaatoa fibera, the atrength and atability are inoreaaed, No other replace-
ment, auoh aa glaaa fibar, ia aa effective,
163
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10.0 ASBESTOS PAPER
Asbestos paper is a very versatile product and therefore has a great
variety of applications. In the electrical industry asbestos papers are used
to fabricate paper tubes and tapes for insulating purposes. The asbestos con-
tent of the paper imparts the thermal and electrical resistance necessary for
its effectiveness as insulation and fire protection for electrical conductors.
Other electrical uses include special laminations for switchboard use, electro-
fine paper, and diaphragms for brine electrolysis cells (Carton, 1974; Daly
et al., 1976).
Coarse grades of asbestos paper are impregnated with bitumen and used for
roofing felts (see Section 9.0) and pipe wrapping. Pipe wraps are used to
provide corrosion-resistant barriers for pipelines and piping. Corrugated
asbestos paper sheets and blocks, usually made up of alternate plies of corru-
gated and plain paper, are employed for appliances at temperatures of up to
300°F. Formed into sectional pipe insulation, this material is used for in-
sulating hot-water pipe, low-pressure steam pipe, and process lines within
its tempera'ture limit (Neisel and Remde, 1966).
Latex-bound asbestos papers are extensively used in the flooring industry
as underlayments for sheet vinyl (Daly JB£ al., 1976).
Other uses of asbestos papers include fabrication of gaskets, general
insulations, beverage filters, molten glass handling equipment, general heat-
fireproof components, and gas-vapor ducts for corrosive compounds.
Asbestos millboard is considered by some to be a very heavy paper and is
in fact very much like thick cardboard in texture and structural qualities.
It can be cut or drilled and can be nailed or screwed to a supporting structure
164
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(Carton, 1974). It is generally used for insulating purposes or for specialty
gasketing.
10.1 Use Quantities and Industrial Firms
According to Table 4.9 (p. 46), U.S. demand for asbestos in paper
products has ranged from 14 to 66 thousand short tons annually during the
1967-1976 period. However, because asbestos paper is used in many secondary
asbestos manufacturing products such as roofing, insulation, and gaskets, it
is believed that the above asbestos demand for paper is much lower than the
actual consumption. As explained in section 9.0, the consumption figures for
asbestos roofing are thought to reflect the amount of asbestos fiber used to
produce the paper which is in turn used to make asbestos roofing. From a
survey of the asbestos industry, Daly et^ al. (1976) have estimated that 38%
of the annual asbestos consumption is used to produce asbestos papers. Based
on the total asbestos consumption of 725,000 tons in 1976, the amount, accord-
ing to Daly estimates, of asbestos consumed in paper would be 276,000 tons.
Table 10.1 below gives the estimated quantities of asbestos fibers used for
all paper products in 1976.
Table 10.1. 1976 Asbestos Consumption in Paper Products
(SRC Estimates)
Product Quality
(103 tons)
Roofing 215 (from Section 9.0)
Gaskets 8 (from Section 13.3)
Insulations 6.6 (from Section 12.3)
All Other 31 (from Table 4.9)
260.6
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The total estimated in Table 10.1 reflects a general agreement with the data
obtained by Daly et^ al. (1976). It should be noted that asbestos millboard
figures are incorporated into Table 10.1. Igwe (1974) estimated that about
15 tons of millboard are produced daily; on an annual basis this represents
about 4,500 tons of production. While it is believed (SRC estimate) that
millboard production may be somewhat higher than 4,500 tons per year, it
still represents only a small fraction of the asbestos papers.
The Census Bureau does not have separate listings for all asbestos
paper products; however, the data which are available from the Census Bureau
for asbestos paper are given in Table 10.2.
Table 10.3 lists the major manufacturers of asbestos paper along
with their respective locations. Most of the plants have diversified product
lines.
10.2 Manufacturing Process Technology
Ingredient formulas for asbestos papers vary widely depending upon
the intended use of the paper. The asbestos content of the finished paper may
vary from 5% to essentially 100%, but a 70-90% content appears most common
(Daly et^ arl., 1976; Carton, 1974). Nearly all of the asbestos employed in
papermaking is of the chrysotile variety, grades 4 through 7. Several hundred
tons of crocidolite asbestos are annually used, primarily to make paper discs
for automobile transmissions (Clifton, 1977). The binder content of asbestos
paper accounts for 3-15% of its weight. The two major binder groups are starches
and elastomers; less frequently used binders can include glue, cement, and
gypsum. Choice of asbestos and binder content depends upon the desired proper-
ties and intended applications of the paper. Mineral wool, fiberglas, cellulose,
166
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Table 10.2. Quantity and Cost of Asbestos Used in Paper and Millboard Products
(U.S. Bureau of the Census, 1972) -'
Materials Consumed
SIC 1972 1967
°,UCt _ . . Quantity Delivered Cost Quantity Delivery Cost
Lode Description (10QO tong) (mllll
-------
Table 10.3. Major Manufacturers of Asbestos Paper
(Carton, 1974; Stewart et al., 1976;
industry communications}"
Manufacturer
Location
Johns-Manville
Pittsburg, Calif.
Waukegan, 111.
Manville, N.J.
Fort Worth, Tex.
Celotex Corp.
Armstrong Cork
Nicolet Ind.
GAF Corp.
Hollingsworth and Vose
Linden, N.J.
Cincinnati, Ohio
Fulton, N.Y.
Ambler, Pa.
Hamilton, Ohio
Norristown, Pa.
Erie, Pa.
Whitehall, Pa.
E. Walpole, Mass.
168
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latex, and many other constituents can be used to provide special properties
and may represent as much as 15% of the paper's weight (Daly e£ al., 1976;
Carton, 1974).
Figure 10.1 illustrates the typical manufacturing operation for
production of asbestos paper. The process is actually quite similar to that
of A-C pipe, especially in terms of potential environmental emissions. A
brief description of the process is given in section 9.2, and will therefore
not be included here.
Asbestos millboard is manufactured almost identically to paper. A
flow diagram is included in section 12.2.
10.3 Quantities of Asbestos Released to the Environment from Manufacture
listed in Table 10.4 are the estimated quantities of asbestos released
to the environment from asbestos paper manufacture. Please note that the
estimates in Table 10.4 do not include releases from paper made for roofing,
insulation, or gasket purposes; releases from these purposes are given in
sections 9, 12, and 13, respectively. The estimates are based upon the 1976
consumption of 31,000 tons of asbestos as listed in Table 4.9 (Clifton, 1977).
The estimates in Table 10.4 were derived by methods which are
explained in the following subsections.
10.3.1 Release from Process Wastewaters
The raw water discharge from a typical asbestos paper manu-
facturing process contains about 19 pounds of suspended solids per ton of
product produced (Carton, 1974). For asbestos paper production we have assumed
that the suspended solids are approximately 80% asbestos fibers because the
average asbestos content of the raw materials la about 80%. It is also
assumed that the clarifiers which settle the suspended solids are 96% efficient
169
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RAW MATIRIALI
ITORAQB
PROPORTION INO
WATiR
JTiAM
•TOOK OHBIT
MITIRINO
PAPIR
MAOHINI
WATIR
DRYING
•TORAQI
WAITIWATIR
OUARIPIOATION
(IAVB-ALL)
OOOLINQ WATIR
OONOINIATI
OONSUMIR
OR
ROOF I NO PLANT
Figure 10.1. Aibesfiea Pspef Manufaeturing
(Qarten, 1974)
17Q
-------
Tibia 10.4. intimated Annual iRviffonmemwl Rel*a»i« of
*— Paptt Manufa«6yfa (IRQ lutlmfia)
(ah@n
fiwmji 01? UndfiUi
pteduee anil attap n,at emaU aa U ean b» ri*pyplt^i
8§p
riri§8 UO
i
blndsFfl, butt fr«i»fibtf^
a
Ivem
emtsslonw
A
Deaa net Inelude aabaa^di reefing, tnaulacien, of iaakei
-------
(Carton, 1974), and that about 38,750 tons of asbestos paper products are
annually produced for purposes other than roofing. The efficiency factor for
the clarifiers may be questionable, as explained in Section 7.3.2. The 38,750 ton
figure was estimated by assuming that 31,000 tons of raw asbestos fiber are
annually consumed for purposes other than roofing, etc. (from Table 10.1) and
by assuming that the finished paper product is 80% asbestos on average. Therefore:
38,750 ton product 19 Ib solids x 0.8 Ib. asbestos x .96 eff. = 5.65 x 10 Ib
yr ton product Ib solid yr
or 283 tons asbestos settled by clarifiers
y*
Unlike asbestos-cement product plants, asbestos paper plants do not use Portland
cement, and the solids in the clarifiers (save-alls) do not tend to form solid
concretions. Hence, free-fiber release from the clarifier sludge may be poss-
ible. While a certain portion of the waste solids may be recirculated, this is
usually not practiced in the industry due to the use of both starch and elastomer
binders which are not compatible. In general, most of the suspended solids
(sludge) collected from clarifying units or ponds are disposed in landfills;
this was the practice noted by most asbestos paper plants field tested by
Stewart et aJL. (1976). Two asbestos paper plants field tested by Stewart et_
al. (1976) released process wastewater to local sewer systems.
For cellulosic papers, it has been reported that product losses
in the wastewaters should be somewhat less than 1% of production (Whitney et al.,
1967). Note that the figure of 283 tons calculated by the above method is 0.9%
of production, which is in good agreement with the percentage reported by
Whitney et_ al. (1967).
172
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The water effluent from the clarifiers also contains asbestos
fiber; the quantity of asbestos released via this source has been estimated
by two separate methods. Many asbestos paper plants recirculate water from
the wastewater treatment facility back to the process and the effluent
volume is considerably less than the raw water discharge; an effluent flow
of 3300 gals./ton product, at exemplary plants, has been reported by Carton
(1974). Carton has also reported that the raw water discharge contains
680 mg/liter suspended solids before clarification. After clarification,
with a 96% efficiency, the water would contain 27.2 mg/liter. Therefore,
the following computation can be made to estimate the amount of asbestos
fiber released to water:
38,750 ton product 3300 gal discharge 27.2 mg 3.785 liter 0.8 Ib asbestos
yr ton product liter gal Ib solid
1 Ib solid 1 ton 11.6 tons asbestos Discharge to water
453600 mg X 2000 Ib yr
The second method of estimating asbestos release in water
effluents is based upon monitoring data of asbestos concentrations. The level
8 12
of asbestos in the final effluent has been measured at 10 -10 fibers per
liter by Stewart et_ al. (1976) in field testing of six separate asbestos
paper plants. The wide range was apparently caused by differing methods of
waste treatment. Using an average of 10 fibers per liter, the following
calculation can be made:
10 -9
10 fibers 3.785 liter 10 grams 3300 gal discharge „ 38750 ton product v
liter gal 103 fibers A ton product yr
1 ton £ 5.4 tons asbestos discharge
9x10^ grams yr
173
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"Of the industrial locations sampled, plants manufacturing
asbestos paper present the greatest potential for contamination of surface
waters by asbestos" (Stewart et al., 1976).
10.3.2 Release from Process Scraps and Baghouses
Rejected papers, scraps, and trimmings are apparently not
wasted in significant amounts; Carton (1974) states that trimmings, defective
paper, and other waste paper can usually be returned to the beater and repulped
for recycling. It would seem possible, however, that a small amount of waste
paper may be wasted to landfills. This potential quantity is difficult to
estimate because there is no available data on which to base estimates. The
best assumption appears to be that only a very small percentage of production
is wasted.
As explained in section 9.3.2, there are no direct monitoring
data on which to base estimates for releases from baghouses used exclusively
for asbestos paper production. However, it may be possible to apply the
Harwood and Ase (1977) monitoring data, for A-C pipe baghouses, that about
0.45% of production quantities is collected by baghouses. It has been pre-
viously noted that the production operations of A-C pipe and asbestos papers
are very similar. Applying this 0.45% figure to asbestos paper production,
excluding roofing paper, etc., it can be determined that about 140 tons of
asbestos fibers are collected by baghouses. A percentage of this collection
may be recycled to the process; however, Table 10.4 assumes that all collection
is wasted.
Using the Siebert £t al. (1976) baghouse efficiency of 99.99%,
it can be calculated that about 0.014 tons of very short fibers are emitted
174
-------
annually by these baghouses. Another way of calculating fiber emissions is
by using the relationship of 1.34 Ibs of fibers emitted per year per 100 CFM
rating, as developed in section 7.3.1 for baghouses. Using this value, it can
be estimated that perhaps a ton of fibers may be emitted annually.
10.4 Release of Asbestos From Use of Paper Products
The potential release of asbestos fibers from use of various paper
products is partially covered in other sections of this report. Roofing paper
is discussed in section 9.4, insulation paper in section 12.4, and gasket paper
in section 13.4. These uses represent over 88% of the annual asbestos consump-
tion in papers. Potential fiber release from other uses of asbestos papers is
discussed below.
10.4.1 Floor Underlayments and Pipe Wraps
Latex-bound asbestos papers are extensively used in the flooring
industry as underlayments for sheet vinyl (Daly et al., 1976). Due to the
application of the paper beneath the vinyl flooring, it is difficult to
envision any fiber release during actual use. Installation of the paper may
result in some fiber release or exposure to workers; however, there is no
monitoring data to confirm or reject this supposition. .As is the case for
most asbestos products, the predominate amount of asbestos fiber content is
wasted to landfills when product replacement is done. It is estimated that
this type of flooring may require replacement every ten to twenty years, and
that perhaps 75% of annual production is intended for replacements.
Another large-scale use of asbestos papers is for pipe wrap-
pings to provide a corrosion-resistant barrier. Again, there is no monitoring
data available to confirm or reject fiber release during use. Wrapped pipe
which is buried in the ground will hardly be able to release airborne fibers;
175
-------
however, it is possible that ground moisture may be able to attack the paper
and allow some fibers to be leached out. Again, the major release of asbestos
is considered to be to landfills at replacement time. Pipe wraps which are
primarily used as insulation are discussed in section 12.4; there it is noted
that in some pipe wraps the binder in the paper may breakdown from long-term
use, thereby causing the material to become friable.
10.4.2 Diaphragms for Brine Cells
About 70% of the American chlorine production is produced by
the diaphragm cell process (Treskon, 1976). In this electrolytic process of
brine, the actual cathode surfaces are generally lined with a layer of asbestos
either in the form of paper or of vacuum-deposited fibers (Deutsch e£ ad., 1963;
Treskon, 1976). The function of the asbestos diaphragm is to maintain the NaOH
strength and to minimize the diffusional migration of hydroxyl ions into the
anolyte. All diaphragms gradually clog with the residual impurities that have
not been removed from the brine and also with particles of graphite from the
anode. The diaphragms are therefore renewed at regular intervals (Deutsch
et^ al., 1963). Typical renewal intervals of these asbestos diaphragms are
100 days or slightly longer (Dahl, 1975). It is assumed that worn-out asbestos
diaphragms are disposed to landfills.
Deutsch et_ al. (1963) reports that asbestos consumption during
cell operations is 1.20 Ibs. per ton of produced chlorine. In 1976, about
10 million tons of chlorine were produced (U.S. Dept. of Commerce, 1977).
Assuming that 70% of production used asbestos diaphragms, then approximately
4,200 tons of asbestos were consumed during electrolysis. This consumption
is believed to be the total weight of the clogged asbestos diaphragms which
are no longer useable and are, therefore, disposed of.
176
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10.4.3 Beverage and Drug Filters
Asbestos paper pads are commonly used in the filtration of
beverages (Biles and Emerson, 1968; Cunningham and Pontefract, 1971; Wylie,
1973). Types of beverages which are filtered with asbestos include beer, wine,
and soft drinks.
An asbestos filter sheet is a specialized filter material which
is used for small to medium size operations requiring the removal of small
quantities of fine or very fine solids; these filter sheets are mainly used to
remove micro-organisms from liquids (Wylie, 1973). In addition to asbestos
fibers, these filter sheets contain cellulose fibers and diatomaceous earths.
They resemble filter paper 3.0 to 4.0 mm in thickness. Patents for asbestos
filters were first obtained in 1918 in Germany. The essential ingredient,
asbestos fiber, permits high permeabilities with really effective filtration
properties.
The use of asbestos to filter liquids leads to the supposition
that perhaps some free-fibers may be released during use, and, therefore,
asbestos fibers may be present in the final beverage product which is consumed.
Biles and Emerson (1968) identified asbestos fibers in commercial beer products
with a rough concentration of 5,000 fibers per pint. However, it was assumed
that the concentration was subject to a wide variation due to variability in
commercial filtration processes. They also identified asbestos fibers in
filtrates that were passed through asbestos filters.
Cunningham and Pontefract (1971, 1973) examined a wide variety
of beverages which are filtered with asbestos. Their results are tabulated in
Table 10.5 along with examinations of tap water, melted snow, and river water.
Wehman and Plantholt (1974) detected asbestos in commercial gin.
177
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Table 10.5. Asbestos Fibers in Beverages and Water
(Cunningham and Pontefract, 1973)
Sample
Beer
Beer
Beer
Beer
Sherry
Sherry
Sherry
Port
Vermouth
Vermouth
Soft drink
Soft drink
Soft drink
Soft drink
Tap water
Tap water
Tap water
Tap water
Tap water
Tap water
Tap water
Tap water
Melted snow
River water
a
Source
Canadian 1
Canadian 2
USA 1
USA 2
Canadian
Spanish
South African
Canadian
French
Italian
Ginger ale
Tonic water 1
Tonic water II
Orange
Ottawa, Ottawa River (F)
Toronto, Lake Ontario (F)
Montreal, St. Lawrence River (F)
Hull, Quebec, Ottawa River (NF)
Beauport, Quebec, St. Lawrence River
(6 km below Quebec City) (NF)
Drummondville, Eastern Townships,
Quebec, St. Francois River (F)
Asbestos, Eastern Townships,
Quebec, Nicolet River (F)
Thetford Mines, Eastern Townships,
Quebec, Lac a la Truite (NF)
Ottawa, top 30 cm (2-3 weeks preci-
pitation)
Ottawa River, at Ottawa
No. of fibers/L,X106
4.3
6.6
2.0
1.1
4.1
2.0
2.6
2.1
1.8
11.7
12.2
1.7
1.7
2.5
2.0
4.4
2.4
9.5
8.1
2.9
5.9
172.7
33.5
9.5
aF, Filtration plant used; NF, no filtration plant used.
178
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The degree to which fibers are released to consumable beverages
from asbestos filters cannot be quantified from the available data, although
some high fiber counts have been noted. It may even be argued that the avail-
able data do not conclusively prove that asbestos fibers are released from
filter pads. The reason is, in none of the studies available to date has the
concentration of asbestos fibers in the water used to make the beverages been
determined. Asbestos fibers are found in many surface waters, and it is pos-
sible that water used to make beverages contained fibers before the beverages
were made. Therefore, the degree to which filters may contribute fibers to
beverages cannot be determined without additional data.
Asbestos fibers have also been detected in parenteral drugs
(Nicholson ejt aJL., 1973). Parenteral drugs are drugs which are injected intra-
venously or intramuscularly. Several decades ago, the pharmaceutical industry
found that asbestos filters are useful and effective for removal of foreign
matter from parenteral solutions, and, therefore, these asbestos filters have
become widely used. However, Nicholson et_ al. (1973) identified chrysotile
asbestos in approximately one-third of the samples from two sets of 17 widely
used parenteral drugs. Once again the conclusion can be drawn that the presence
of asbestos in the drug solution may be the result of asbestos filtration.
Although asbestos fibers were found in only one-third of the
samples, Nicholson et^al. (1973) noted that negative or indefinite results for
a particular sample did not guarantee the absence of asbestos in the drug lot
from which the sample was taken. A single vial is an inadequate sample of a
i
large production run. Additionally, the drugs, sampled represented only a small
fraction of those on the market.
179
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It can be noted that in the U.S. no asbestos-containing or
other fiber-releasing filter may be used in the manufacture, processing, or
packing of such Pharmaceuticals, unless it is not possible to manufacture that
drug product or component without the use of such a filter (U.S. Food and Drug
Admin., 1976).
10.5 Alternatives to Asbestos in Paper
In general, asbestos papers are unique due to the unequaled properties
of asbestos fibers, namely heat, chemical, corrosion, and rot resistance coupled
with dimensional stability. Substitution of the asbestos fiber by an alterna-
tive fiber, such as fiberglas, glass, ceramic, or other mineral fiber, may
permit a useable product to be produced. However, the alternative fiber will
be more costly and the performance will usually suffer. Within the economic
restraints of the various markets, the substitution of asbestos by some alter-
native fiber in paper products is just not economically practical at present.
For some applications of asbestos papers, alternative products or
methods are'currently available. Alternatives to asbestos paper used in roofing,
insulations, and gaskets are discussed .in sections 9.5, 12.5, and 13.5, respec-
tively.
An alternative to asbestos diaphragms in electrolytic cells has been
developed and demonstrated by Hooker Chemical Co. (Dahl, 1975). The alterna-
tive is a membrane-cell consisting of a film of perfluorosulfonic acid resin
(a copolymer of tetrafluoroethylene) and another monomer to which negative sul-
fonic acid groups are attached. The membrane-cells are more expensive than the
asbestos diaphragms and are apparently still in a developmental stage. The
overall economics of conversion to membrane-cells cannot be ascertained at this
180
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time; however, these cells appear to be a very viable alternative to asbestos
diaphragms in future years.
Expanded perlite has been successfully used as a substitute for
asbestos filters in some applications such as bulk liquid filtration (Fulmer,
1976). Perlite is a form of glassy rock similar to obsidian. It usually
contains 65-75% SiO_, 10-20% Al_0_, 2-5% H., and smaller amounts of soda,
potash, and lime, When perlite is heated to the softening point, it expands to
form a light fluffy material similar to pumice. Expanded perlite does not,
however, replace asbestos in most cases.
181
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11.0 ASBESTOS FLOORING
Asbestos floor tiles are produced in the United States for use in commer-
cial applications, offices, and homes. The shortest grades of asbestos fibers
are used in vinyl and asphalt floor tile manufacture. The asbestos fibers are
used to impart strength, dimensional stability, and resistance to the cold. At
present, vinyl asbestos floor tile (VAT) accounts for most of the asbestos used
in this category, with asphalt tile serving some special applications and appli-
cations where darker shades are permissible.
11.1 Use Quantity, Shipment Values, and Industrial Firms
U.S. demand for asbestos in flooring products has ranged from 113 to
218 thousand short tons annually during the 1967 to 1976 period; in 1976, 113
thousand short tons of asbestos were used in flooring products (Clifton, 1977).
Only the chrysotile variety of asbestos is used. According to the 1976 figures,
about 15.6% of the total U.S. market for asbestos was consumed in the production
of flooring. This is the third largest use of asbestos fiber, ranking behind
roofing and A-C pipe.
Table 11.1 lists the shipment values and quantities of asbestos floor
tile as given by the Census Bureau. In 1967, asphalt-asbestos floor tile made
up about 15% of the asbestos floor tile market compared to vinyl-asbestos tile's
85%; however, by 1972 the market for asphalt-asbestos tile had fallen to comprise
only 5% of the asbestos floor tile values. Competitive pressures from alternative-
flooring products is the primary reason for the decline of the asphalt-asbestos
market.
In fact, in recent years the vinyl-asbestos floor tile market has been
less than spectacular as a result of strong competition from carpeting and
182
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00
Table 11.1. Shipment Values and Quantities of Asbestos Floor Products
(U.S. Bureau of the Census, 1972)
Total Product Shipments, including inter plant transfer
SIC
Product
Code
32925 11
32926 —
32926 13
32926 15
32926 00
Product
Asphalt Floor Tile
Vinyl Asbestos Floor Tile
Plain backed
Adhesive backed
Vinyl asbestos, n.s.k.
1972
Quantity
(million sq yd)
9.8
—
129.4
—
__
Value
(million $)
9.1
199.3
151.3 ->
48.0 >
i
J
1967
Quantity
(million sq yd)
28.0
143.5
143.5
Value
(million $)
25.0
153.5
153.5
-------
linoleum (Igwe, 1974). The market for all types of vinyl (PVC) flooring, which
includes vinyl-asbestos and all other kinds of vinyl floorings, declined from
about 50% of all basic floor coverings in 1961 to only 30% in 1971. As a point
of reference, about 67% of all vinyl flooring in 1969 was of the vinyl-asbestos
type (Frey, 1976). The phenomenal growth in the use of tufted carpets in both
residential and commercial buildings is the main reason for the decline. How-
ever, vinyl flooring is now believed to have firmly established its market share
according to 1971 figures (Frey, 1976). This implies that significant increases
in the use of asbestos for flooring are not likely to occur in the foreseeable
future.
Table 11.2 lists the major manufacturers of asbestos-flooring products
along with their respective locations and estimated 1975 sales.
The 1976 floor tile consumption of 113 thousand tons of asbestos
would produce roughly 105 million sq. yds. of asbestos flooring.
11.2 Manufacturing Process Technology
Floor tile manufacture involves proprietary production line processes
highly developed by the individual manufacturers. Equipment layout, process
description and compound formulations are held very confidential because the
industry is highly competitive (Daly et^ al., 1976).
The asbestos content of the tile ranges from 8-30% by weight (Carton,
1974) and usually comprises very short fibers, grades 5 and 7 (Table 4.10,
p. 46). Each square foot of tile may contain upwards of 0.13 pounds asbestos
fibers (Daly e£ al_., 1976). PVC resin serves as the binder and makes up 15-25%
of the tile; chemical stabilizers usually represent about 1%. Limestone and
other fillers make up 55-70% of the weight. Pigment content usually averages
about 5%, but may vary widely depending upon the materials required to produce
the desired color (Carton, 1974).
184
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Table 11.2. Major U.S. Manufacturers of Asbestos Fi -ring
Manufacturer
Plant Location
Estimated 1975 Sales c
Asbestos Flooring
(millions of dollars)
American Biltrite
Rubber LaMirada, Cal..
Armstrong Cork Co. South Gate, Cal.
Kankakee, 111.
Jackson, Miss.
Lancaster, Pa.
Economic Information Systems, Inc.; SRC Estimates
Monetary values are in 1975 dollars.
5.7
36.5
Flinkote
GAF Corp.
Kentile Floors
Los Angeles, Cal.
Chicago, 111.
New Orleans, La.
Long Beach, Cal.
Joliet, 111.
Vails Gate, N.Y.
Houston, Tex.
Brooklyn, N.Y.
20.3
14.4
6.6
14.4
15.0
17.4
8.7
29.5
TOTAL 168.5
185
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Most floor tile manufactured today uses a vinyl resin, although some
asphalt tile is still being produced. The manufacturing processes are very
similar and the water pollution control aspects are almost identical for the
two forms of tile (Carton, 1974). Figure 11.1 shows the general manufacturing
process.
The ingredients are weighed and mixed dry. Liquid constituents, if
required, are then added and thoroughly blended into the batch. After mixing,
the batch is heated to about 150 degrees C and fed into a mill where it is
joined with the remainder of a previous batch for continuous processing through
the rest of the manufacturing operation. The mill consists of a series of hot
rollers that squeeze the mass of raw tile material down to the desired thickness.
During the milling operation, surface decoration in the form of small colored
chips of tile (mottle) are sprinkled onto the surface of the raw tile sheet and
pressed in to become a part of the sheet. Some tile has a surface decoration
embossed and inked into the tile surface during the rolling operation. This
may be done before or after cooling. After milling, the tile passes through
calenders until it reaches the required thickness and is ready for cooling.
Tile cooling is accomplished in many ways and a given tile plant may use one
or several methods. Water contact cooling in which the tile passes through a
water bath or is sprayed with water is used by some plants. Others use non-
contact cooling in which the rollers are filled with water. In some plants,
the sheet of tile passes through a refrigeration unit where cold air is blown
onto the tile surface. After cooling, the tile is waxed, stamped into squares,
inspected, and packaged. Trimmings and rejected tile squares are chopped up
and reused (Carton, 1974).
186
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RAW MATERIALS
STORAGE
PROPORTIONING
CONDENSATE
FORMING
ROLLING
COOLING
WATER
a.
COOLING
COOLING
WATER
WASTEWATER
FINISHING
CUTTING
PACKAGING
STORAGE
CONSUMER
Figure 11.1. Asbestos Floor Tile Manufacturing Operations
(Carton, 1974)
187
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11-3 Quantities of Asbestos Released to the Environment from Manufacture
In the manufacture of asbestos vinyl tile, water is used only for
cooling purposes. Both contact and non-contact cooling are usually employed.
Water does not come into contact with the tile until it has been heated and
rolled into its final form. In this stage it is completely inert to water
(Carton, 1974). Therefore, wastewaters will contain little, if any, asbestos
fibers. Stewart et al. (1976) found asbestos concentrations of less than
10 -10 fibers per liter in wastewaters from Armstrong's Kankakee, 111. floor
tile plant.
Additionally, trimmings and rejected tile squares are chopped up and
reused. Therefore, there are only minor amounts of manufacturing scraps dis-
posed to landfills.
The only major source of asbestos release to the environment from
floor tile manufacture is from baghouses, both air emissions and collection
dumpings. There are no direct data available by which to make direct estimations
of these baghouse collections and emissions; however, the manufacturing process,
in this regard, is similar to that of the mastic asphalt mix for roofing. As
developed in section 9.3.4, it was estimated that perhaps 0.2% of production
volumes, for the mastic roofing mix, were collected by baghouses. Applying
this figure to floor tiles, about 227 tons of asbestos fibers are annually
collected in baghouses. The Siebert et^ al. (1976) baghouse efficiency of 99.99%
indicates that 0.0227 tons of fibers are emitted into the atmosphere annually.
The alternate method for predicting baghouse emissions given in section 7.3.1
would estimate emissions to be on the order of one ton.
188
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11.4 Release of Asbestos from Asbestos Flooring Use
By far, the major release of asbestos to the environment from flooring
use occurs at replacement time when old flooring is removed and disposed to
landfills. Service time for asbestos floorings depends upon the severity of
use; accordingly, service life may vary from 10 to 30 years. Therefore, a
healthy percentage of production is intended as flooring replacements. This
percentage may be in the neighborhood of 40-60%.
During the service life of an asbestos floor various forces act upon
it and the result may be a release of free asbestos fibers. Forces such as
walking, scrapping, cleaning, and machine scrubbing may be sufficient to break-
down the vinyl matrix and allow asbestos to escape. However, there has been no
study conducted to determine if, or how much, asbestos may be released during
use or cleaning. Such a study may be desirable.
The following hypothetical example of asbestos fiber release from
flooring use is intended to illustrate a potential magnitude of emissions which
can be theoretically calculated from various assumptions. Daly et al. (1976)
have reported that each sq. ft. of tile may contain up to 0.13 Ib asbestos;
therefore, it is assumed that each sq. ft. of tile contains 0.13 Ib asbestos.
Additionally, the following assumptions are made: (1) the average service-life
of an asbestos floor is 20 years; (2) approximately 10% of the flooring is worn
away during the service-life by use and cleaning; and (3) about 1% of the "worn-
away-flooring" becomes airborne. It is visualized that wear on the floor will
not be even over the entire surface because sections may be covered may be
covered by equipment, desks, etc.; however, it is assumed that sections of the
floor which are worn away disperse airborne fibers uniformly throughout the
189
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entire room. Therefore, the following computation can be made which gives the
amount of asbestos emitted per day, on average, from each square foot of asbes-
tos tile:
Ib asbestos 0.10 wear „ _ _, . . _ ... , grams
=; x X 0.01 airborne X 453.6 A
ft 20 yrs Ib
0.003 Srams etted - 3.6 xlO6 -S8-- " 8.2 x 103
. --5- .
yr/ft yr/ft day/ft
It is now assumed that each square foot of tile is installed 10 feet below the
3
ceiling; therefore, each square foot is topped by 10 ft of air. Assuming
2
ventilation design requires 15 air changes per hour, then 1 ft of tile will be
3 3
topped by approximately 3600 ft of air each day, which is equivalent to 102 m
of air each day. Therefore, assuming uniform mixing of air and airborne asbes-
tos fibers, the average asbestos concentration of the air is raised daily by:
8.2 x 103 nfi emitted _ 8Q ng_ = 8 x 1Q-5
102 m m cm
3
Using the conversion factor of 10 asbestos fibers per nanogram, the air con-
3 3
centration of 80 ng/m is equivalent to 0.08 fibers/cm . The above assumptions
predict that the average asbestos concentration of the air above an asbestos
3
floor can theoretically be raised by daily use of the floor by 0.08 fibers/cm .
3
This 0.08 fiber figure is based upon the estimation that 1 nanogram equals 10
fibers which is, in turn, based upon electron microscopy count. Rohl et al.
190
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(1975) have indicated that the number of fibers visible by electron microscopy
is perhaps one hundred fold as compared to an optical microscopy method which
counts only fibers of 5 pm in length or longer. The optical microscopy method
for counting fibers 5 ym or longer is used for determining compliance with OSHA
regulations. On this basis, the concentration of fibers emitted by asbestos
flooring, if measured by the OSHA optical microscopy method, in the above exam-
3
pie would be 0.0008 fibers/cm .
It should be noted that the example given above is only supposition.
Monitoring is required to determine actual concentrations, if any. Under practi-
cal conditions, it would be unlikely that all fibers released by use would
become airborne. A large percentage would probably be incorporated into water
used for cleaning purposes which would then be released into wastewaters. This
is the reason for assuming that only 1% of worn material would become airborne.
11.5 Alternative Products to Asbestos Flooring
Asbestos flooring competes principally with carpeting, linoleum, and
sold vinyl flooring. At present, about 95% of all asbestos flooring is vinyl-
asbestos. As indicated earlier, in section 10.1, all types of vinyl floor
coverings make up about 30% of the flooring market; and, in 1969, about two-
thirds of the vinyl market was asbestos-vinyl. Therefore, in the late 1960's
and perhaps, early 1970*s, vinyl-asbestos flooring covered about 20% of the
total flooring market. However, this 20% figure has decreased and is decreasing
somewhat due to the popularity of various types of non-asbestos vinyl flooring.
In recent years, coated types of vinyl flooring (plastisol-coated felts) have
moved strongly into flooring markets of all cost levels at the expense of vinyl-
asbestos tile (Frey, 1976).
191
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The newer types of vinyl flooring are produced as roll goods and
typically have a felt or other backing (e.g., asbestos felt coated with styrene-
butadiene latex). This backing receives a foamed plastisol coating, the surface
of which is decorated with a pattern by rotogravure printing or so-called chem-
ical embossing, and then is covered with a clear plastisol wear layer (Frey,
1976).
Apart from reinforcing the final product, the asbestos fibers perform
a function in giving the polymer sheets "wet-strength" during the manufacturing
process (Green and Pye, 1976). Alternative fibers to asbestos do not have all
of the performance characteristics unique to asbestos. As far as asbestos
flooring is concerned, the alternative fibers mentioned in other sections of
this report are potentially useable, but the final product is somewhat inferior
and more expensive. Whether such a product is marketable at this time is doubt-
ful.
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12.0 ASBESTOS INSULATION
Asbestos used for thermal and electrical insulation materials amounted to
1 1/4% of the total U.S. output of asbestos products in 1976. The use was
divided between the two classifications as follows (Clifton, 1977):
Thermal Insulation = 6600 tons
Electrical Insulation = 2300 tons
Total 8900 tons
The uses for insulation have dropped drastically from 25,000 tons/year in 1973,
where it had held consistently for 10 years (Table 4.9). The decreased con-
sumption has followed restrictions that recent health protective limitations
impose (EPA, 1974). At the current consumption, asbestos insulating materials
are less than 1% in value of the total market for all insulation materials.
Projected trend is for further decrease in asbestos insulation because of
health, as well as economic, disadvantages.
In spite of the small and decreasing current use of asbestos for insulation
purposes and a possibility for nearly complete replacement, the disposition of
the extensive, previously installed insulation materials for industrial and
commercial buildings and equipment will continue to be an important source of
asbestos release to the environment. Controls of these demolition procedures
for old installations are an important factor in preventing release of the dan-
gerous fibrous material to the environment (EPA, 1974).
12.1 Asbestos Insulation Products, Uses, and Economic Trends
Asbestos fiber is used for thermal insulation in a variety of forms
and compositions to conserve energy, to control temperatures, and to protect
personnel and equipment from elevated temperatures. Asbestos fiber is also
193
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used for electrical insulation in various forms where the system may be exposed
to elevated ambient temperatures. As in many other applications, asbestos may
be used also to increase the strength and durability of the insulation product
(Neissel and Femde, 1966; Swiss, 1966).
The restriction in use for health reasons is changing the pattern for
asbestos application significantly, and further reduction to lower consumption
is visualized.
Before 1973 asbestos was used generally for insulation applications,
up to about 850°F alone and in mixtures, and up to 1200°F with calcium silicate
in preformed coverings. These uses applied to piping, boilers, tanks, reactors,
furnaces, turbines, and other high temperature operations. For those purposes
requiring specifically designed coverings, asbestos was fabricated in factory
operations into sectional forms alone and with mixtures of other materials for
easy field installation. Eighty-five percent magnesia pipe covering and batts
with 15% asbestos fiber were typical forms for the products.
These products have been phased out (EPA, 1974) and are no longer
produced. Asbestos for thermal insulation is produced only in the form of more
common materials, i.e., paper, millboard sheet, and textile coverings, as well
as loose powder for mixing with water and additives to form plaster. These
materials are fabricated into required forms during installation at field
locations.
For electrical insulation, asbestos was used in the form of paper,
roving, webbing, and braid for systems where comparatively high ambient temper-
ature may occur. Substitutes have been developed and are increasingly used due
to health hazard restrictions. Woven asbestos covering continues to be used at
decreasing rates for electric conductors exposed to high temperatures.
194
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Asbestos fiber has also been used to reinforce plastics and ceramics in switch
and connector boxes, terminals, and as paper to line junction and switch boxes.
A breakdown of the grades and types of asbestos used in the above
products in 1976 is given in Table 12.1.
As with roofing, the finer grades of chrysotile are the principal
constituents of the insulation products. Also, as in the case of all U.S.
fabricated products, about 90% of the milled fiber is Imported from Quebec,
with only about 10% produced in the several U.S. mines in Vermont and the
Southwest (Table 3.1).
U.S. producers of asbestos paper, millboard sheet, and spun fiber
products that are potentially adaptable to insulation applications are listed
in Table 12.2. However, with the exception of Johns-Manville at Waukegan, none
are understood to be presently producing materials for thermal insulation
(Barnhart, 1977).
The spun fiber products made in the listed plants may be used for
electric insulation and principally for cable and wire covering by specialty
and appliance fabricators.
In addition to the above manufacturers of prime asbestos materials,
the 1975 Thomas Register lists about 50 companies selling insulation materials.
These companies sell and fabricate various specialities made from the prime
products. Some of these can be used for insulation purposes.
The value and quantities of the insulation materials for the past few
years are summarized in Table 12.3. The figures for the more recent years are
extrapolated from the data reported earlier.. The 1974 and 1976 data include
very few prefabricated factory products, such as were produced and included in
the 1967 and 1972 figures.
195
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Table 12.1. Distribution of Asbestos Minerals Used for Insulation (short
tons) (Clifton, 1977)
Mineral Form
and Grade Thermal Insulation Electrical Insulation
Chrysotile
Group 3 100
Group 4 800
Group 5 200 100
Group 6 1900 200
Group 7 3600 1900
Total 6500 2300
Crocidolite
Amosite 100
Anthophylite
Total (tons/year) 6600 2300
Total (%) 74 26
196
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Table 12.2. U.S. Manufacturers of Asbestos Paper, Millboard, and Spun Fiber
Adaptable for Insulation
A. Paper and Millboard (Carton, 1974)
Johns-Manville
Celotex Corporation
GAF
Nicolet Industries
B. Spun Fiber Products (Margolin, 1975)
Johns-Manville
Amatex Corporation
Southern Asbestos
Raybestos-Manhattan
Waukegan, 111.
Manville, N.J.
Linden, N.J.
Cincinnati, Oh.
Erie, Pa.
Hamilton, Oh.
Amber, Pa.
Manville, N.J.
Meridith, N.H.
Morristown, Pa.
Charlotte, N.C.
North Charleston, N.C.
197
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00
Table 12.3. Value of Asbestos Insulation Products (approximated from 1972 Census of Manufacturers
Data)
Total Annual Consumption
32927.35 Piping
32927.37 Block and others
Total asbestos products
1000 tons
$106
$106
$io6
1967 1972 1974
22- 24- 14-
17.3 20.7 10(b)
8.8 12.8 5(b)
26.1 33.5(c) 15(b)
1976
8.9
6.5(b)
3.3(l>)
9.8(b)
(a)
From Bureau of Mines figures (Clifton, 1977) for annual consumption. Bureau of Census data
is for production. Interchangeable use assumes exports and imports are equal.
Prcra£ed from 1^/2 census data from Bureau of Mines production figures.
(c)
The Asbestos Information of North America, reported value at $40.9 million for 1971.
(Asbestos, 19/3)
-------
Comparisons with 1972 U.S. Bureau of Census data for mineral fiber
insulation and for fiber glass products indicate that present value of asbestos
insulation would total not more than 1% of the value of all insulation materials
produced. For example, the value of mineral wool insulation averaged as fol-
lows for 1967-1972:
For structural insulation SIC 32961 - $242 x 10,
For industrial insulation SIC 32962 - 329 x 10
Total $571 x 106
If other materials, such as organic fibers, are also included, a
total annual value approaching $1000 million is visualized for the entire
present insulation industry. Hence, at about $9.8 million, the annual value of
asbestos materials is less than 1% the total and is decreasing.
12.2 Manufacturing Technology
The manufacture of insulation products may be considered under two
categories, namely factory fabricated and field fabricated materials.
Factory fabricated insulation materials include especially preformed
or molded articles produced as sectional parts for easy installation. These
include sectional pipe covering, blocked batts, and molded parts that have been
mixed and compounded with such materials as magnesia, calcium silicate, and
plastics. Before 1973 asbestos fiber was added for temperature protection and
strength. As explained earlier, uses of these asbestos materials have been
phased out and are not currently used (EPA, 1974). Similarly, decreasing
quantities of asbestos paper and millboard sheets continue to be produced for
thermal insulation applications as part of the larger quantities of those
materials produced for other purposes, such as roofing and building materials.
199
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The manufacturing processes for paper are described in Section 9.2.
The manufacture of asbestos millboard is shown diagrammatically by Figure 12.1
and is essentially the same as for asbestos paper by the cylinder machine pro-
cess. For millboard, multiple layers of pulp are built up to about 1/2" by
successively adding plies from a series of cylinders, followed by pressing,
drying, and finishing. The products are about 95% asbestos. Uses of water for
pulping and washing are the same as in paper making. Also, recycling water and
the recovery of pulp and disposal to waste are the same as in paper making
(Section 9.2 and Carlton, 1974).
Rope, roving, and other partly spun asbestos fiber materials used for
electrical insulation are made by the same methods used in cotton and wool
milling. The fiber is successively graded, carded, combed, and drawn to make
roving and spun fiber (Labarthe, 1975; Margolin, 1975). Material for the
ground and conductor insulation products may be taken at any point such as the
combed mat, roving, thread, or twisted cords as rope, web, or braid. These are
mechanical operations that can be hooded and ventilated with bag or other
filters to collect released fiber. However, asbestos has been nearly com-
pletely replaced by other insulation for all electric uses with the exception
of coverings for cable and wire and for appliance specialties where there is
high temperature exposure.
Field fabrication of thermal insulation consists principally in
adapting usual forms of asbestos material, such as paper and millboard sheets,
to industrial equipment and structures. The installation varies with the shape
of the equipment on which the insulation is installed. For piping, flues, and
circular stacks, paper, millboard, cloth or tape is wrapped around the objects
200
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RAW MATERIALS
STORAGE
PROPORTIONING
WATER
r
RECYCLED SOLIDS
RECYCLED WATER
MIXING
FORMING
DRYING
TRIMMING
CLARIFICATION
(SAVE-ALL)
SOLIDS
WASTEWATER
--J
SLUDGE
FINISHING
STORAGE
CONMMIR
Figure 12.1. Asbestos Millboard Manufacturing Operations (Carton, 1974)
201
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in layers. This can be fixed to the surface with wire, bands, or sheathing.
Fabric covering can also be applied with or without coating or paints. For
furnaces, boilers, turbines, reactors, kettles, or other heated vessels, the
asbestos millboard is attached to the surfaces by studs, bolts, bands, expanded
mesh, or sheet metal. Dry asbestos fines are mixed into paste with water and
adhesives for hand trowel or spray application to fill joints between the
millboard sheets. The outside surface is finished by coating with cement,
plastic, or fabric. The field installation may involve trimming, sawing,
drilling, and grinding to fit the insulation material to the equipment. With
the phasing out of factory preformed materials, all installations of asbestos
insulation are currently following field fabrication procedures (EPA, 1974).
For electrical insulation, adapting factory formed asbestos material
such as paper, roving, tape, or batting to the electric equipment in the multi-
tude of electric manufacturing shops may be considered as field fabrication for
installed asbestos material. These electric shop operations primarily Include
the following (Swiss, 1966):
Motor and transformer winding - The asbestos material in these
applications is imbedded into the armature or core coil slots, either manually
or mechanically, to give ground or conductor Insulation. The operation in-
volves handling dry friable material and consists in separating, Inserting,
cutting, and forming the asbestos fibers received as strands, braids, or roving
> i
in and around conductors. Asbestos insulation is especially useful for appli-
cations where the electric equipment is exposed to higher ambient temperature.
This application is no longer used by manufacturers of large equipment. It is
possible that it is used to a small extent by small specialty shops.
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Conductor covering - Dry asbestos threads are braided onto conductor
wires or cables, or batting impregnated with plastic is pressed onto and around
the wire. These applications are used especially for services where high
temperature occur. This is visualized as the principal remaining use of asbes-
tos for electrical insulation.
Molded insulation parts - Although not primarily used for insulation
purposes, asbestos is added to plastic and ceramic mixes to strengthen molded
electric accessory parts, such as switches, connectors, and terminal bases and
boxes. The asbestos fiber is mixed with the plastic or ceramic composition,
fed to molds, and cured. The parts may require grinding, machining, or drill-
ing.
The escape of dry asbestos fiber in the above operations into working
areas is controllable by hooding and adequate ventilation. Bag filters or
other separators are used to collect the fibers that may be released. These
operations may occur at any of the many manufacturers of specialty machines and
parts.
12.3 Asbestos Released to the Environment During Manufacture
Considering manufacture again in two categories, factory and field
fabrication, release of asbestos during production and installation (emission
control techniques are described in EPA (1973) publication) can be outlined as
follows for each:
Factory fabrication - Under the current situation, where preformed
insulating materials that contain asbestos are no longer produced, asbestos
release in the factory operations chargeable to the manufacture of insulation
products will be a fraction of that resulting from the larger production of
paper and millboard sheet for the wider uses of these prime materials. The
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asbestos released in the manufacture of roving or braid type material for
electrical insulation will similarly be a fraction of the total from production
of these materials.
For paper and millboard, the releases will be prorated fractions of
the quantity approximated for paper in Section 4.3. For the roving and braid
materials, a similar approximation will be made. For the millboard operation,
the release will be approximately the same as for paper per unit product.
Also, it is assumed that all the thermal insulation or 6600 tons will be paper
and millboard sheet. The releases consequential to thermal insulation would
therefore be 3.5% of the release for roofing paper at its output of 85% of
215,000 tons per year (Table 9.3, Section 9.3.7). These releases apply to
wasted scrap, to losses in air emission, and to waste water. These are shown
in Table 12.4. Recovered dust from bag filters is approximated also at 3.5% of
the roofing quantity or about 30 tons/year.
No data is on hand for the releases from the roving or braiding
operation for the electrical insulation. Releases would, however, occur in
grading, carding, combing, and treating the dry fiber. It is judged that the
losses as scrap would follow paper manufacturing. The loss would be negligible
since scrap would be recoverable as pulp for paper or board. Losses from the
ventilation system would be larger than for paper because of the number of
operations involved. The emission from the bag filters is therefore justified
to be higher than for paper, as indicated in Table 12.4. There would be no
waste water loss.
Releases of asbestos from the many and differing sites for field
fabrication are even more indefinite. It is judged, however, that the releases
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Table 12.4. Environmental Release of Asbestos from the Manufacture and
Installation of Insulating Materials (SRC estimates approximated
from 1976 consumption)
Point of Release
Annual Release (short tons)
I. In Factory Fabrication
A. Thermal Insulation
Scrap to waste
Wastewater solids to waste
Wastewater effluents
Air emissions from bag filters
Baghouse collections
B. Electrical Insulation
(Rovings and Spinnings)
Scrap to waste
Air emissions from bag filters
Baghouse collections
negligible
70
1.0-3.0
<0.1
30
(a)
negligible
<0.2
20
(a)
II. From Site Fabrication and Installation
A. Thermal Insulation
As scrap, all materials
By air emission
with dust collection
without dust collection
B. Electrical Insulation
Scrap to waste
In air emissions from filters
50-100
30
15-20
(b)
(a)
(b)
Based on nearly complete recycle.
Includes contingency for spills, floor washing, etc.
205
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that would result from fitting, trimming, forming the materials* and finally in
pointing-up joints with asbestos-containing plasters, would be in the order of
0.5% to 1.0% of the installed materials as scrap to waste. Water losses would
not occur. For field installation, it is probable that eventually portable
bags for dust collection with portable hoods and ventilating system may be used
for the larger installations. Releases without these provisions are excessive
and are under scrutiny by EPA (EPA, 1974). Although the releases at any loca-
tion may not be significant, the exposure to the installation contractor's
personnel is continuous and high. The air emission released during field
fabrication and installation is shown in Table 12.4 for both cases, i.e., with
and without portable ventilating and dust collecting equipment. Recycling the
dust collected by the filters may not be feasible under field conditions and no
reduction in releases is obtainable; however, better control of the loss should
be beneficial.
Table 12.4 indicates that in the field fabricated operations, release
of material is more than in the factory operations. This approximation reflects
inability to recycle scrap and also the poorer, if any, ventilation and dust
collecting systems. As indicated above and by EPA (1974), the use of asbestos
insulation material for field fabrication may also be phased out eventually.
The fate of the released asbestos to the environment as approximated
in Table 12.4 will vary with local conditions. Typical cases are conceived as
follows:
Scrap waste - From factory operation, scrap and other waste from the
insulation production will be a small fraction of larger operations. These
wastes, if any, are normally transported and deposited under plant control with
206
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provision to protect the public and will follow OSHA regulations for waste
disposal (Anon., 1976). For field installation, scrap is usually picked up
with trash collecting systems for disposal in public dumps or for landfill.
Special control of friable dust losses is seldom used during transportation or
unloading or in providing protection at the dump.
In the dump or landfill, the asbestos waste will become less of a
concern in the buried locations where it is left.
In waste water - The asbestos content in the waste water is transported
with the outflow into neighboring streams, lakes, or ponds until velocity drops
and the solids deposited in stable shoals or beds, such as in Section 9.3 and
other sections.
Airborne losses - The asbestos dust as initially emitted to the
atmosphere will follow the prevailing wind, eventually settling on the ground
and exposed surfaces. It will finally be washed away with rain or melting snow
into streams along the same course as the waterborne material.
Disposal of asbestos waste by some form of incineration may release
asbestos fibers into the atmosphere. Carlin (1977) has estimated that of the
asbestos products disposed to municipal dumps or landfills, approximately 9% is
destined for incineration. Carlin (1977) additionally estimated that incinera-
tion of all types of asbestos products annually emits about 220 short tons of
free-fibers from all municipal incinerators; this estimate is based upon many
assumptions and the accuracy is not certain. However, asbestos fiber releases
from incineration may be a contributing factor to urban monitoring of airborne
asbestos. Fibers could conceivably be lost in flue gases and in handling of
cinders. However, at the current low production level of asbestos insulation
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materials, the fraction of the total loss attributive to this operation would be
very small - say less than 5-10 tons/year.
12.4 Asbestos Released to the Environment from Installed Insulation
The intitial condition of installed asbestos is generally preserved
with little deterioration over its considerable service life. Loss in strength
of the asbestos occurs only where temperature may have been excessive. Other
additions to the insulation mixture, however, may deteriorate by wear or acci-
dent. Also, maintenance, replacements, and renovation may be required before
the equipment finally must be removed. The above conditions apply to the
existing insulation for equipment and structures which were installed before
current restrictions were involved, and specifically when asbestos Insulation
consumption averaged about 25,000 tons per year.
To approximate the releases that currently prevail under these
present conditions, the following annual rates of disposition have been derived
from the following economic pattern in terms of the total installed material:
Disposition of material required for: % per year
Maintenance and repairs = 2 (a)
Equipment replacement =* 4 (b)
Structural demolition =• 2.5 (c)
(a) Based on total labor and material at 5% per year with 40% material
(b) Based on average life at 25 years
(c) Based on average life at 40 years
In addition, the overall rate of growth is taken at 1.5% per year,
and the division between process equipment and structurally dependent material
at 75% and 25%, respectively. This distributuion is approximated from 1972
Census of Manufacturers data for mineral wool insulation (SIC Code 3296), which
excludes asbestos insulation. These average 58% for equipment insulation and
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42% for structural insulation. It is Judged that because of the special re-
quirements for asbestos, at least 75% would be used for equipment in the case
of asbestos.
On the above basis, if T - total presently installed asbestos
insulation, the rates of use would be related as follows:
.75 (.02T -I- .04T) + . 25 x .025T + .015T = 25,000
or installed material T = 380,000 tons
and from which the annual disposition of the installed asbestos amounts to the
following:
For maintanenance and repair » 5700 tons/year
For equipment replacement = 11,400 tons/year
For demolition of structure = 2400 tons/year
Total replacement = 19,400 tons/year
On the basis of the above distribution of installed asbestos insula-
tion, the fate of each category is visualized as follows:
In cases of maintenance and repair work, the removed insulation will
usually be scrapped at numerous locations around the country and removed by
usual waste collecting systems and deposited in landfill or trash dumps. The
eventual fate would be similar to site fabricated waste (Section 12.3). It is
judged that about 50% of the above equipment replacement materials would follow
the same pattern.
For the remaining material replaced for renovation of larger equipment
installations and for structural demolition, the controls required by OSHA
(Anon., 1976b) and EPA (EPA, 1974) may be followed. These provisions required
advanced notice before demolition or removal; separate removal of the asbestos
insulation and wetting with water during removal and transporting. For these
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cases, the trend is to increase the precaution in handling the scrap, such as
bagging and transporting and handling under controlled conditions to avoid dust
and accidental exposures (Anon., 1976b). The restricted conditions applied
especially where the scrapped material releases friable fibers. Limitations
are not applied if asbestos is non-friable. "Friable asbestos material" is
defined by EPA as "any materials containing more than 1% asbestos by weight and
that can be crumbled, pulverized, or reduced to powder (when dry) by hand
pressure" (EPA, 1974). The foregoing restrictions apply directly to enforce-
ment of work practice standards for working conditions under OSHA control.
These restrictions had not been formerly applicable to environmental emission
control by EPA as a result of a court ruling dismissing a case against Adamo
Wrecking Co. in January 1978. The dismissal was on the basis that work prac-
tice standards were not applicable for alleged emission violations by EPA.
Presently, the Clean Air Act Amendments of 1977 (Anon., 1978) does permit work
practice limitations to be used as a standard for emission control where other
methods of measurement are not applicable. It is expected that a further
modification for enforcement of the regulation will follow. The effect of the
changes are not certain, however. Some greater amount of airborne asbestos
contamination may result, limited, however, by OSHA restrictions (Anon., 1976b),
In summary of the above, it is seen that disposal through repairs,
replacement, and demolition will involve approximately 20,000 tons per year of
discarded asbestos insulation. This is currently the major release of asbestos
insulation products to the environment. It will fade out as the presently in-
stalled materials are replaced with asbestos-free insulation. However, the
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disposition will be near the above rate for about 15-20 years. It is judged
that approximately 60% of the quantity will be discarded through usual, uncon-
trolled municipal trash collecting systems. Only about 40% will be removed
under controlled demolition systems as currently regulated. Guidelines for
controls are outlined in EPA (1978) publication.
12.5 Alternative Materials to Asbestos for Insulation
Asbestos insulation, which is used principally for its heat resisting
properties, can be replaced by fiberglass with or without calcium silicate for
the lower range of temperature conditions, or up to about 1000°F, and by mineral
wool with refracting ceramic fibers over higher ranges. The non-deteriorating
property of asbestos is also obtained with these materials; the higher strength
of asbestos fiber is not obtained. High strength, however, is not usually a
critical requirement for insulation.
The prices of the asbestos insulating products range from 50C to $1
per Ib. Alternate materials are obtainable with no economic disadvantage with
respect to price or insulation value. For example, comparisons of price fac-
tors and insulation values, reciprocal of conductance, for asbestos millboard
and for asbestos paper with fiberglass board and with mineral wool are pre-
sented in Table 12.5.
The low conductance gives fiberglass and mineral wool appreciably
better insulating value than asbestos on both weight and surface area bases.
Lower densities give these materials further economic advantage over asbestos.
This advantage with the health consideration explains the continuing decrease
in asbestos for insulating purposes.
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ro
Table 12.5. Comparison of Asbestos with Other Insulating Material
(Basis = 1 square foot and 1 inch thick insulation)
Asbestos
Millboard
Paper
Fiber Glass
Mineral Wool
Thickness
per ply
1/2"
1/16"
1"
1"
Number
of plies
2
16
1
1
Weight per
sq. ft.
4.6
5.0
0.25
1.1
Prices(b)
K Factor
1
1
0.36
0.44
Per lb.
$0.46
$0.32
$0.56
$0.68
Per ft.2
$2.10
$2.60
$0.14
$0.75
Maximum
temperature
1800
1200
1000
1900
(a) K = BTU/hr/°F/inch/ft.2
Price and other information from suppliers' district offices.
-------
13.0 PACKING AND GASKETS
Asbestos fiber used in 1976 for packing and gasket products amounted to
2.8% of the total U.S. consumption of the mineral. The 1976 consumption,
20,100 tons (Clifton, 1977), decreased about 25% from a consistent level near
25,000 tons per year for the 10 year period before 1974, shown by Table 4.9.
The drop was partly due to use of substitute materials since 1974 to lessen
exposure to asbestos and its health hazards (EPA, 1974). Increasing uses of
newly developed products also reduced consumption (Jewitt, 1977).
As in the case of insulation, the removal of installed packing and gasket
materials in the maintenance, removal, and demolition of container equipment
will generate the principal release of asbestos into the environment. In most
cases, the asbestos is not in free-fiber form due to impregnations or coverings
that encase the fibers. Asbestos has been used for packing and gaskets for many
years. Consumption is expected to continue near current level due to the advan-
tages of the fiber compared to substitutes and because the hazardous fiber form
of the material is not employed.
13.1 Asbestos Packing And Gasket Products, Uses And Economic Factors
Asbestos fiber is used in packing and gasket products because of its
physical properties and comparatively low cost. The principal physical advan-
tages are the strength and resilience, especially under compression, and the
suitability to high temperatures and to a wide range of corrosive conditions.
It is also adaptable to spinning into yarn and textile materials.
The asbestos materials are used in many forms and compositions for
packing and gasket products. Commercial grades of asbestos starting with the
fiber, sheet, or yarn are fabricated into compressed sheet, into beater impreg-
nated sheet, and into impregnated millboard and yarn. The products may be
213
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sheathed in metal, plastic, or cloth, or reinforced with wire insertions. The
products may be factory preformed or molded into desired shapes or field cut and
fitted from the sheet, millboard, yarn, or molded compositions.
Although the above prime products are made by 22 principal fabricators
(Table 13.1), much of the material is packaged and resold by a large number of
small specialty companies. The 1975 Thomas Register lists about 200 companies
under subsections covering asbestos gasket and packing suppliers.
For static applications, the gaskets provided as above are installed
to obtain tight non-leaking connections for piping and other joints, such as at
the covers and openings on all types of industrial and commercial equipment.
For dynamic applications, packing is provided as a form of bearing for revolving
or moving parts in stationary supporting members that also prevents leakage of
the contained fluid along the bearing surface. The packing, usually in the form
of rings of the material, is held by pressure against the moving part. Lubrica-
tion required at the separatory surface is provided by external or impregnated
lubricants.
A breakdown of the grades and types of asbestos used in 1976 for
gaskets and packing products is given in Table 13.2.
Table 13.2 Distribution of Asbestos Mineral Used For
Packing and Gaskets (Clifton, 1977)
(short tons)
Mineral Form and Grade Chrysotile
Group 3 1,800
4 5,900
5 8,300
6 700
7 3.300
Total 20,000
Crocidolite 100
TOTAL 20,100
214
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Table 13.1. Major U.S. Manufacturers Of Asbestos
Gaskets, Packings (Margolin and Igwe, 1975)
FIRM LOCATION
Raybestos-Manhattan, Inc. Stratford, Conn.
Nicolet Industries Ambler, Pa.
Johns-Manville Corp. Manville, N.J.
Garlock, Inc. Palmyra, N.Y.
Felt Products Mfg. Co. Skokie, 111.
McCord Corp. Wyandotte, Mich.
Amatex Corp. Norristown, Pa.
Gatke Corp. Chicago, 111.
Anchor Packing Co. Philadelphia, Pa.
Vellumoid Division Worcester, Mass.
Green, Tweed N. Wales, Pa.
Crane Packing) Morton Grove, 111.
F. D. Farnum Lyons, 111.
Sterling Packing & Gasket Co. Houston, Tex.
Detroit Gasket & Mfg. Co. Detroit, Mich.
A. W. Chesterton Everett, Mass.
Hercules Div. of Richardson Corp. Aiden, N.Y.
Braiding & Packing Works of America Brooklyn, N.Y.
Sacomo Packing Co. San Francisco, Calif.
Sepco Birmingham, Ala.
Quality Gasket & Mfg. Co. Clawson, Mich.
Armstrong Cork Co. Braintree, Mass.
215
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As indicated, group 4 and 5 arc uaad for 70% of tha product!, prin-
cipally as fibar and woven matariala. Imported milled flbar la tha principal
raw material (Table 3.1).
The ahiptnent valuaa of aabaatoa packing and gaakata ara shown in
Table 13.3. It la estimated that gaakata consume 66% of tha raw aabaatoa flbar
In the gaaket and packing claaaification, or aabaatoa conaumptlon for gaakata la
roughly twice that for packing.
Tha ahlpmant valua of all typaa of gaakat and packing products In 1976
la estimated to be roughly $900 million. Tha total valua of aabaatoa gaakat and
packing producta In 1976 la estimated at $70 million In Table 13.3, or roughly
82 of all theae producta. The tabulated approximation valua of the aabaatoa
producta (about 8% of the total claaaification) la conaldarad too low by manu-
facturers of theae matariala. An estimate that the currant valua of ahipmant
waa $250 million per year, or 25% of tha total claaaification, waa given (Jewltt,
1977). The reason for the difference la believed to be due to the mark-up on
prlcaa by vendors of specialty producta, which Cenaua data do not reflect.
13.2 Manufacturing Technology
The manufacture of gaakata and packing aabeatoa producta may be con-
(
aldered under two classification*; namely, matariala for static purposes, auch
as gaaketa for pipe joints, and producta for dynamic uaaa, auch aa pump and
platon ahaft packing (Flaher, 1967).
13.2.1 Caaketa
Moat gaaket materials ara either compraaaad or beater aaturatad
ahaeta. Compressed sheet la made from a plaatic mixture of fiber, an elaato-
roeric binder and a solvent, The mixture feeda a aheetlng machine in which there
216
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(D.S. Bureau of the Census, 1972; SIM: estimates)
Total Product Shipments,
Tnrlwlin* T^t^rplant" Tr^w?^«»'"
^*
(All values in Millions of dollars)
SIC
Product 1976 1974
Code Gaskets: Value Value
32932 13 Compressed Asbestos f
32932 IS Beater Saturated Asbestos 35* < 50*
32932 17 Asbestos Cloth L v.
32933 00 Packing and Miscellaneous 35* 50*
TOTAL VALUE ALL PRODUCTS 70 100
1972 1967
Value Value
24.5 ^
19.2 J 62.1
2.4 J
50**
96.1
* Adjusted for inflation and reduced production; also, approximated fron Census Value on basis
thar price «f rorfclnr Is «4ua) ••« tv*«** w*w o* *^*?fc«»t*iw «*« pnondan* basis.
** Approximated from SIC 32933-71 plus 32933-00 with allowance for the total estimate by Asbestos
Information Assoc./BA * $99.5 million for 1971 (Margolin and Igve, 1975).
-------
are two steel herisental revolving eylinders, placed with close clearance, The
•mailer cylinder or roll presses the mixture onto the larger roll as it is
•lowly separated (ran the larger roll, The larger roll la heated to drive off
the solvent and to compact, the sheet, The large roll, about 40" diameter by
130" length, produeea a sheet 120 inches square. The product containa about 201
binder euoh an rubber, ehleroprene, or any special material that may be required.
The beater saturated sheet is made in a paper machine. The
binder is added to the asbestos pulp in the beater aa it feeds the machine.
More elaatomevic binder is used than in the above calender type compressed
product. The product Is used for leas eevere services than the compressed
•heet,
Asbestos millboard sheet as selfbonded fiber, with practically
all mineral and with little binder, is ueed for highest temperature services,
The construction has less strength so it requires good support or supporting
reinforcement.
AMh@Nte« paper with wire reinforcing as well as impregnated woven
asbestos in also fabricated into gaskets for special services,
white (ehrysotile) and blue (crocldolite) asbestos are used up to
about 900*I*1, Blue asbestos is used preferably to white for strong mineral acids
ana alkalis, The fabrics are graded from commercial grade at 73-801 asbestos
for temperatures of 400*7 to AAAA grade at 99-1001! asbestos for tsmperatures of
900"P (Table 14,1 and I'Inure 14.2),
13,2.2 Dynamic Packing
Dynamic packing requires ahaping, either by molding, machining,
or forming the product with a non-abrasive material, to minimise wear at the
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contact with the moving part, Lubrication ie aleo required. Thie can be im-
pregnated into the packing or added separately, For theee product!, the aebee-
toi yarn or braided material la impregnated with tht lubricating additivt,
•ithir in preparation or in molding, Tht raquirad forma ara obtained by preae-
ing into daairad croaa aectiona, Tha formad product may than ba coatad with
graphic* or othar matariala, Aleo, libar or yarn may ba uaad aa rainforoamant
to olaatomere, auoh aa rubbar, and moldad to daairad croaa aactional ahapaa,
13,3 Aabaatoa Released To Tha Bnvironmant During Manufacture
Tha ralaaaa of aabaatoa during manufacture will be conaldered aepar-
ately for the fabrication of the prime material* produced by the 22 manufac-
turere lieted in Table 13,1 and for the larger number of vendore who may reform,
package, or reaall the prime materiala aa apecialty producta. Bmiaaion control
tachniquee are given fully in EPA (1973) publication.
In the manufacture of the prime materiala for gaaketa and packing,
auch aa millboard and yarn, the releaae contributed by the production of theee
materiala will be a fraction of that cauaed by the production of the larger
total operationa that would be involved. There will be added to theae approxl-
mationa releaaea due to eolvent recovery required for the impregnating opera-
tiona.
The following aeparate manufacturing operationa ara involved and are
conaidered in approximating the releeaea to the environmenti
Comproeeed aheet gaaketa production
Beater impregnated gaakete production
Impregnating millboard operation
Impregnating yarn operation
Molded producta
For releaae aa acrap to waate, it ia judged that the amount would be
between 0,5 and II of the total production. Thia would be largely aa trimminga
219
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and cuttings. Because impregnated scrap cannot be recycled, full loss in this
range is visualized and applicable to full production of 20,100 tons/yr.
Loss with waste water would apply to the impregnated beater saturated
and millboard materials. It is approximated that these would have, on a unit
production basis, the same loss as paper making (Table 9.3). Assuming that over
one-third of the production falls in these classifications, as judged by Bureau
of Census figures (Section 13.1), or at 8,000 tons/yr, the loss would be about
4% of Table 9.3 figures, or between 2 and 4 tons/yr.
Emission from baghouse filters is expected to follow approximately the
same unit production release as paper making. Therefore, at 20,100 tons/yr for
all above operations, the release would be 10% of Table 9.3 figures or less than
0.1 ton/yr. In addition to the air filter emission, emission from the solvent
recovery operations is reported to be between .09-.18 lb/1000 Ibs of the
finished product (Margolin and Igwe, 1975). This would total for all products
10 to 20 tons/year.
The above approximations are summarized in Table 13.4.
The release of asbestos to the environment from the many distributors
and rehandlers of packing and gasket materials is difficult to judge. If it is
assumed to be essentially all as scrap from cutting and reforming, it might be
conservatively in the order of 0.5 to 1%, or 10 to 20 tons/yr. The loss applies
to full consumption to cover similar losses from material used directly at site.
No significant loss of airborne material is visualized because the asbestos is
encased for nearly all products by elastomers, plastics, graphite, or lubricants.
The fate of the released asbestos shown by Table 13.4 is visualized to
be the same as conceived for insulation materials (Section 12.3). Again, scrap
220
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Table 13.4. Environmental Release of Asbestos from Manufacture of Gasket
and Packing Materials (SRC Estimates)
Point of Release Annual Release
(short tons)
I. In Factory Fabrication
scrap to waste 10-20
wastewater solids to waste 100
wastewater effluents 2-4
air emissions from bag filters <0.1
baghouse collections 35
emissions from solvent recovery 10-20
II. From Specialty Distributors and Field Installations
as scrap to waste 10-20
221
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from the factories would usually be deposited in landfill locations with protec-
tive provisions. The scrap from the specialty distribution is usually collected
by public trash handlers with less care. Also, losses with waste water would be
carried away by existing streams or flows. In nearly all cases, however, it is
visualized that material would be encased with stabilizing additives and would
not be susceptible to becoming airborne.
13.4 Asbestos Released To Environment After Installation
Asbestos gaskets are subject to wear only where used for frequently
opened covers, manholes, and doors. The main uses of asbestos gaskets for pipe
flanges and other permanently fixed positions only require replacement for main-
tenance, process revisions, or long-term equipment replacements.
Asbestos packing used essentially for dynamic services is subject to
direct wear against the rotary shaft, piston, or moving part. A small fraction
of the material will be released with lubricant leakage or into the contained
mediums. The major release will be when the packing is scrapped during periodi-
cal replacement. It is judged that 90% of the packing consumed annually will
be released in the form of worn out material.
In accordance with above conditions, the annual releases of asbestos
are approximated for installed uses as follows:
For Gasket Materials, at 2/3 total consumption
25% has less than 1 year life *
60% is for maintenance and long time replacement
15% is for new installation.
For Packing Materials, at 1/3 total consumption
10% as immediate wear
90% at annual life of 1 year or less
Annual consumption is taken at earlier rate of 25,000 tons/yr for
replacement losses.
222
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For Gaskets Tons/year
Short life uses =• 20,100 x 2/3 x .25 3,300
Maintenance replacement - 25,000 x 2/3 x .60 10,000
For Packing
As immediate wear - 20,100 x 1/3 x .10 700
As wastes scrap = 20,100 x 1/3 x .90 6,000
Total Release 20,000
Above approximate current release is based partly on former annual
consumption approximating 25,000 tons. The release will drop slightly from
above as release becomes consistent with lower current consumption.
The fate of the material follows about the same as concluded for
insulation in Section 12.4. About 50% of the above is scrapped without special
precautions and is removed by usual trash hauling facilities to waste dumps or
landfill operations. It is visualized that the other half is handled in accord-
ance with EPA restrictions as outlined in Section 12.4.
13.5 Alternative Materials To Asbestos For Gaskets And Packing
No completely satisfactory substitute for asbestos in gasket and
packing applications is known. The combination of high strength and resiliency
under compression, as well as resistance to high temperature and to a wide range
of acid-alkali conditions makes asbestos unique at a comparatively low price
range for the products. For example, fiberglas and mineral wool do not have the
strength of resilience; organic and elastic fibers do not have temperature and
chemical resistance. Teflon and graphite carbon compositions are at least five
times the price.
Substitution has been possible only for lower temperature, low pres-
sures, and non-corrosive conditions.
For packing and gasket applications, the asbestos fiber is encased in
binding additives. It is therefore not readily airborne and is non-fibrous
since it is contained in a matrix.
223
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As a consequence of the above factors, it is visualized that little
further replacement will occur and consumption will continue at near or above
present rate.
224
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14.0 TEXTILES
Textile products amounted to only 1% of all U.S. asbestos uses in 1976. The
annual uses for textiles, 7,400 tons, as reported by the Bureau of Mines for
1976, dropped more than 50% from the 10 year level of over 15,000 tons (Table 4.9)
(Clifton, 1977). The decreased use resulted from limitations imposed by health
control hazards (Anon., 1976b). Glass fiber was the principal substitute mate-
rial.
End use textiles, classified as above, are estimated to be roughly less than
one-third of all manufactured asbestos textile materials. The latter include
intermediate products used for other classifications such as friction, insula-
tion, and gasket products (Sections 6, 12, and 13).
It is believed that the use of end use textiles may have leveled off and may
slowly rise as more dust-free materials and processes develop, and assuming
controls do not become more restrictive.
Textile products have generally short life applications. Release to environ-
ment therefore averages near consumption level, principally as worn out scrap to
waste dumps. Nearly all the materials are impregnated or coated to suppress
dust; hence, the potential for fibrous dust emission is low, except for occa-
sional uncontrolled conditions.
14.1 Uses and Economic Factors
Asbestos has been known and used for textiles to resist fire and heat
since ancient times. Modern commercial operations have been well established for
more than 100 years. Chrysotile, as used for textiles, is stable up to 900°F and
can be used for continuous operations up to 900°F; chrysotile can also be used in
higher temperature applications, but only for interrupted periods of time (Anon.,
225
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1967). Fibers above 1/4 inch are readily spun into yarn, cord, thread, cloth,
roving, rope, tape, braid, and corded fibers (Figure 14.1). These primary
textile materials are fabricated into protective clothing, curtains, blankets,
filters, diaphragms, and other articles where resistance to flame, fire, heat,
and exceptional corrosion is required.
The above products are used industrially in welding, for furnace and
other flame or high temperature operations, and for equipment such as conveyor
belts for hot materials. Other uses include diaphragm fabric for electrolytic
cells and lap and carded fiber for beverage filter media, although asbestos
papers are more commonly used for these purposes. The above applications are
exclusive of intermediate textile materials used for other products such as
brake lining, electric insulation, and pump packing, as covered by Sections 6,
12 and 13.
The pure asbestos products, usually coated with acrylic or similar
resins to suppress dusting, can also be reinforced with cotton and other fibers
or with metal wire and sheaths. They can also be sprayed with aluminum to
further reflect heat effects.
The strength retention of plain asbestos fibers for the several
grades at elevated temperature is shown by Figure 14.2 and the asbestos content
for the several grades by Table 14.1.
The distribution of asbestos fiber used for textile products with
respect to grade and mineral is shown for 1976 by Table 14.2 (Clifton, 1977).
All are in the longer grades as required for spinning.
226
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FIBER PREPARATION
I
Figure 14.1 (Anon., 1967)
227
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CHART A
GRADE AAAA
GRADE AA
UNDERWRITERS' GRADE
•J'U IV .**'•> *«• Q/V^ • C-V •"*•".
;*!::•*.'.*!•* *V'.HW J;«S *.;;'•
STRENGTH RETENTION
OF PLAIN (non-metallic) ASBESTOS TEXTILES
after 24-Hour Exposure
to Temperatures of 400*. 600* and 800°F
PERCENT STRENGTH RETENTION
I I 1
Figure 14.2 (Anon., 1967)
228
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Table 14.1. Percentage of Asbestos Content by Weight in Asbestos Textile Prodiu-ts
As Established by the American Society for Testing and Materials
GRADE ASBESTOS CONTENT BY WEIGHT
Commercial 75% up to but not including 80%
Underwriters' 80% up to but not including 85%
Grade A 85% up to but not including 90%
Grade AA 90% up to but not including 95%
Grade AAA 95% up to but not including 99%
Grade AAAA 99% up to and including 100%
See ASTM Specification D 1918, page 92, for the test methods used to
determine asbestos content (grades).
229
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Table 14.2. Distribution of Asbestos by Grade and Type 1976
(Clifton, 1977)
Chrysotile
Group 1 & 2 200
3 6900
4 300
TOTAL 7400
Crocidolite, Amosite, Anthophylillite none
TOTAL 7400
As with other products, about 90% of the milled fiber was imported
from Canada. U.S. sources are shown in Table 5.1.
The prime textile materials used by the industry are produced in the
following five plants in the U.S. (Pagan, 1977):
Firm i Location
Raybestos-Manhattan, Inc. North Charleston, N.C.
Marshville, N.C.
Southern Asbestos Co. Charlotte, N.C.
Amatex Corporation Meridith, N.H.
Norristown, Pa.
An approximation of the present annual value of asbestos textiles is
shown in Table 14.3, using 1972 Bureau of Census data and Bureau of Mines con-
sumption figures. The values are approximations assuming average prices, such
as cloth now averaging near $3 per Ib. and yarn near $2 per Ib.
The foregoing review applies only to the production of the primary
asbestos textile materials, i.e., yarn, cord, and cloth. As in the case of
gaskets and packing (Section 13), these prime materials are used by a larger
group of distributors and fabricators that manufacture clothing articles and
other specialties, as well as distribute the prime and treated prime products.
230
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Table 14.3.
Distribution of Quantity and Values of Textile Uses
(U.S. Bureau of the Census, 1972)
SIC
CODE
1967
1972
1974
1976
PRODUCTION (Million Ib)
32927-11 Yarn, Cord & Thread
32927-21 Cloth
32927-31 Others
TOTAL
VALUE (Million $)
9.4
10.2
19.6
17.5
11.1
28.6
20.4 (a) 7.4 (a)
32927-11
32927-21
32927-31
Yarn, Cord & Thread
Cloth
Others
TOTAL
7.1
12.3
11.5
30.9
13.7
15.1
8.4
37.2
30+ (b) 20+ (b)
(a) From Bureau of Mines - Minerals Yearbook 1973 & 1977 for users
(b) Estimate - for 1974 at $1.50/lb
- for 1976 at $2.75/lb
Note: Bureau of Census figure for annual production runs about 40% above
Bureau of Mines figures for uses, indicating an excess of exported
over imported product. With imported textile asbestos in 1976 at
$10 million (Fagan, 1977) a large value for exports is indicated.
231
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It is judged that the rehandling and treating would raise the market value of
current textile output manyfold.
A rough approximation of the fraction of textile end products, as
classified in Table 14.3, is made from the data in Sections 6, 12, and 13 using
1976 figures for uses (Clifton, 1977):
Textiles Materials Used For, Tons/yr
1. Brake lining @ say 15% of 64,000 (Sec. 6) - 9600
2. Insulation @ say 26% of 8,900 (Sec. 12) - 2300
3. Gaskets @ say 34% of 20,100 (Sec. 13) - 6900
TOTAL 18,800
% Textile end-products - 7400 - 28%
18,800 +7,400
of total textile material manufactured.
14.2 Manufacturing Technology
Asbestos textiles are sold in various forms, namely yarn, cord,
thread, and cloth. Also, intermediate products such as roving, mat, braid,
and tape are made in these operations.
Most asbestos textiles are spun from fiber by similar spinning oper-
ations as used in cotton and wool milling (Joseph, 1966). The successive steps
are shown in Figure 14.3. It consists principally in grading and cleaning the
fibers by air classification, carding and combing the fibers into a parallel
arrangement as a mat, then separating the mat into strands that are wound into
spindles to form roving. The roving is spun into yarn, twine, or cord on spin-
ning frames. The yarn is woven into fabric, braid, or tape.
In addition to the established spinning process as covered in the
foregoing, there are new wet processes which are based on forming single filma-
ment fibers by extrusion. These processes, i.e., Raybestos-Manhattan, Novatex
232
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MILLED FIBER STORAGE
ADDITION OF
OTHER FIBERS"
PNEUMATIC GRADING
CARDING AND COMBING
FINES TO RECYCLE
REFUSE TO WASTE
MATTING
MAT AND ROVING
SPINNING
YARN OR CORD
BRAIDING OR WEAVING
BRAID OR FABRIC
Figure 14.3. Asbestos Textile Operation (Margolin and Igve, 1975;
Anon., 1967)
233
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Process, and Turner and Newall Fortex textiles, represent only 5-10% of current
production (Colson, 1977). With these processes the extruded thread is spun to
the cord or cloth as with the fiber. The process consists of making a gelatin-
ous mixture of fine asbestos fiber in water with a volatile dispersant. The
*
mass is extruded through small dies. Threads as fine as 80 cut are made
(Colson, 1977).
To suppress dust (in handling and fabricating the above textile prime
materials), coatings, principally acrylic resins, are applied to most of the
cloth product. This treatment effectively controls dust release, permitting
use within OSHA guidelines (Anon., 1976).
Relatively little water is used in textile manufacture. There is
occasional washing of waste from coating operations (Margolin and Igwe, 1975).
The foregoing applies to the manufacture of the prime materials
before fabrication into consumer end products. These consumer products are
later tailored by many distributors into other forms and specialty products
(Thomas Register, 1975). These involve varied types of operations as required
for cutting, sewing, impregnating, recoating, molding, pressing, and reforming
the prime materials.
14.3 Asbestos Release to the Environment from Textile Manufacture
Release of textile asbestos to the environment falls into two cate-
gories, namely release during manufacture of prime products (yarn, cord, and
cloth) and release during fabrication of the prime materials into consumer
products, clothing, fine curtains, and specialty products.
Releases of asbestos to the environment during manufacture of the
prime textile materials arise from two sources, namely as the scrap to waste and
80-100 yard lengths per pound (Cooper, 1961)
234
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as the emissions in the exit air from bag filters in the plant ventillating
system. The present process has no significant waste water effluents. A small
intermittent amount of wash water is wasted from the coating operation (Margolin
and Igwe, 1975). Also, water is used in the new "wet" processes. The effluent
from these is small and is discharged to city sewers. Wet scrubbers, formerly
used for ventillating systems, are being replaced by bag filters (Margolin and
Igwe, 1975). It is visualized that all the wastes may reach 5% or more of total
production or roughly 500 tons/yr from the several producing plants. This
would also include refuse and sweepings from the grading operation and plant.
The emission of asbestos in exit air from the bag filters in the
plant ventillating systems is judged to be about, twice the emission from the
paper making operation for the roofing industry, per unit production, or about
10% of the approximation in Table 9.3, or a total of less than 0.2 ton per
year.
The releases of asbestos to the environment during the handling and
fabrication of the prime materials into specialty products will be essentially
all as scrap to waste dumps. Some exception may occur when scrap is recycled
to fabricators. It is visualized that scrap to waste may range between 1-2% as
cutting, trimming, and sizing the prime materials into consumers' products, or
approximately 75-150 tons per year from the many distributing and fabricating
sites. The losses of airborne material are insignificant with current OSHA
guide line controls in operation.
The above releases are summarized in Table 14.4.
The,fates of the released asbestos as scrap to landfill or waste
dumps will be the same as visualized for the insulation and packing products
235
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Table 14.4. Approximation of Release of Asbestos to the Environment During
Textile Manufacture
During Manufacture of Tons
Prime Products (a) per year
As scrap to waste 500 tons
In air emissions from plants <0.2
In Fabricating Consumers Products (b)
As scrap to waste 75-150 tons
As air emission negligible
Total Release in Manufacture « 125-200 tons
(a) Approximation applies to the several plants listed in Section 14.1 or
in order of 10-15 tons/plant/year.
(b) Approximation applies to the 50 or more distributing and specialty
fabricators of between 0-5 tons/year/site.
236
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(Sections 12 and 13). The asbestos will eventually become stabilized with the
other waste materials in the deposits. As indicated, the approximated release
is visualized not to exceed about 15 tons per year at any of the many landfill
sites.
14.4 Release of Asbestos Textile Products to the Environment During Use
Textile products generally wear out at a comparatively fast rate. As
a consequence, replacement is approximately equal to consumption, with the worn
out material released as waste to municipal landfill dumps. With currently used
coated materials, no significant quantity of the products is released to the
atmosphere, and it is visualized that essentially all the material becomes waste
or scrap. On this basis, about 7400 tons per year are scrapped and sent to
landfill or other waste dumps. The annual release may be somewhat higher today
due to a backlog from the larger use before 1974. This will soon stabilize
nearer the current consumption level.
These losses, as worn out articles to waste dumps, represent the most
significant release of asbestos to the environment from the textile sector.
This source is widely spread over many dump sites. Also, this source is very
small as compared with those for roofing and other asbestos uses.
14.5 Alternatives to Asbestos Textiles
There is no completely satisfactory substitute for asbestos for many
textile uses. Although glass and mineral fibers are used as fairly good sub-
stitutes, neither has as good heat or corrosive resistant properties or as high
strength. When combined with ceramic binders, application up to 5000°F is
reported (Anon., 1967). Also, the prices of asbestos textiles are comparably
low ($8-$10 per yard) or about the same as for glass. Plastics such as du Pont
Nomex are considerably higher.
237
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The dust suppression coatings that permit ready use of asbestos
products within present OSHA guidelines should encourage contined use of asbes-
tos textiles at near or above current level.
238
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15.0 ASBESTOS COATIBC AMD PADTT COMPOUMDS
Asbestos used for coating and paint compounds in the U.S. in 1976 amounted
to nearly 20,000 tons, as classified in the Bureau of Mines Mineral frismmlity
Profile 1977 (Clifton, 1977). This consumption, which is approximately 3Z of
the total asbestos consumption, excludes the Material used in coatings for
roofing purposes (see Section 9). With roof coatings included, total consump-
tion for all coatings was estimated by an Industry survey to total 67,500 tons
for 1975 (Daly et al., 1976).
•either Bureau of Mines nor Bureau of Census reports have data by which
consumption trends for these products can be estimated. Discussions with sup-
pliers and consumers of coating products give considerably different predic-
tions with respect to future applications of asbestos in these materials. Some
suppliers have abandoned use of asbestos entirely because of OSHA restrictions.
Others continue to use asbestos at essentially the same or higher rates. In
summary, it is judged that the reduction in uses to present level has been ex-
tensive but that the current level will probably be held. The latter results
from accepted realization that in nearly all roaring applications the asbestos
is completely encapsulated. Bo Injurious fibrous type dust Is consequently
released during uses of the products. Also, new uses and products, such as the
short fiber California asbestos, are expected to have Increasing applications
(Anon., 1977).
15.1 uses of Asbestos In Coatings. Paints, and Sealants
Asbestos fiber is used as a filler and reinforcement in asphalt and
tar base coatings, paints, and sealants to Improve the strength, corrosion and
wear resistance, and other qualities of the products.
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Filler materials, with reinforcing properties, modify the properties
of the bituminous compounds (Endersby, 1948). Strength and stability of the
products are improved. The effects of temperature on plastics are controlled.
Resistance to weathering, oxidation, and other wear factors are increased.
High fiber strength and other structural characteristics make asbestos fibers
the most effective reinforcement with respect to these properties.
The asbestos content in bituminous coating mixtures ranges from 10-
12%. The mixtures also contain about 50% volatile petroleum solvents. The
bituplastic or bitumastic mixes are applied to the surfaces by brush, spray
gun, roller, or trowel, depending on the concentration of the asbestos. Other
ingredients are also used as required for service conditions. Figments, rust
proofing chemicals, heat reflecting metallic paints, and other fillers may be
added. Additional insulation materials such as cork, emulsifiers, and resins
are also used. The solvent evaporates after application, leaving a long wear-
ing protection film or coating. Asbestos is especially effective in reducing
the tendency of the binder to flow or crack with changes in temperature.
The above products are used in a wide variety of services (Anon.,
1970). The largest use is for roofing applications, as included in Section 9.
Otherwise, these coatings are used as sealants to moistureproof and waterproof
concrete foundations, side walls, tanks, and structures such as cooling towers
in nuclear power plants. The coatings are applied as light sealants or as
heavier coatings, depending on the asbestos content and number of coats applied.
The products are used as protective coatings for underground pipe
lines and for anti-condensation coatings for low temperature refrigeration
services. They are used for corrosion resistance in exposures to sea water
240
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spray, salt solutions, organic or mineral acids, or petroleum products. Some
automobile undercoatings use asbestos in the protective preparation, especially
if sound deadening is also desired. The coatings are used for fireproofing
structural steel. Aluminum or zinc is added to reflect the heat or to improve
heat resistance properties. The products are applicable to primed metals,
masonry, concrete, plaster, glass, wood, brick, and cinder blocks. Application
of these coatings require adherence to amendments of the Clean Air Act of 1977
and guidelines described in EPA (1978) publication.
Bitumastic coatings with asbestos filler have been used for wood block
and concrete floor mastics, tennis court coverings, chimney stack paints, and
driveway seal coats. Asbestos is a constituent in some texture paints (Anon.,
1976c).
Other resinous liquids are used to a smaller extent as vehicles for
asbestos fillers for special coating applications, especially when controlled
viscosity and thixotropic properties are required (Anon., 1977).
As indicated earlier, many suppliers of coatings and paints have
stopped the use of asbestos as an additive, replacing it with fiber glass,
talc, or other fillers. Other suppliers, however, continue to produce or
*
distribute products containing asbestos.
The asbestos used as filler for coatings, paints, and sealants is
principally made from the grade of mineral shown by Table 15.1. The shortest
grades of chrysotile are used. Over 95% is in Group 7. As with other asbestos
products, about 90% of the milled product is imported from Quebec.
Asbestos coatings, paints, and sealants are made by many suppliers.
The Thomas Register (1975) lists 27 companies that sell asbestos paints. Also,
about 100 suppliers of asphalt paint are listed that may add asbestos to their
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Table 15.1. Distribution of Asbestos Minerals Used for Coatings, Paints,
and Sealants (Clifton, 1977)
Mineral Form and Grade Quantity (short tons)
Chrysotile
Group 4
Group 5
Group 6
Group 7
300
300
100
19,200
Total 19,900
Crocidolite
Amosite
Anthophyllite
Total asbestos tons/year 19,900
242
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products without being classified as asbestos paint vendors. Many in these
groups mix the paints. Others only pack and resell the mixed products.
/
In addition to the above suppliers to the national market, it is
judged that many small suppliers mix smaller quantities of asbestos coatings
for limited local markets.
National manufacturers of asbestos texture paints, as identified by
Anon. (1976c), include Mary Carter Industries (Tampa, Fla.), Bondex International
(Brunswick, Oh.), and Synkoloid Co. (Atlanta, Ga.).
There is no census information o» the value of the asbestos coatings
and paint products being produced. The Bureau of Census reports do not separate
this classification from asphalt and other base paints (SIC Codes 2851 and
2951). However, information developed from industry estimates gives the total
use for all roof and other asbestos coatings as 67,500 tons in 1975 (Daly,
1976). This states that an expenditure for $4.22 million per year would be 1.6%
of total annual sales. On this basis, total sales in 1975 were about $264 mil-
lion. For the 20^000 tons reported by the Bureau of Mines for 1976, the pro-
rated annual value of sales for coatings, paints, and sealants, other than roof
products, would be:
57*5%% x $264 x 106 - $78 million
and the value per ton on contained asbestos would be $3750.
The above value, as well as the quantity for coatings and paints used
in the above approximation, is high in relation to the value and quantity given
for fibrated asphalt roof coatings by the 1972 Census of Manufacturers. The
figures for this use, SIC Code 29522-51 (generally considered higher than the
other coatings), were $20.6 million for value and 44.2 million gallons. The
latter would be less than 20,000 tons if 10% asbestos, or a value of $1000 per
243
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ton of asbestos. To explain the inconsistency, it is believed that the Bureau
of Census data covers only the use by identified major producers and excludes
the large number of small suppliers of asphalt paints and coatings that use
asbestos but are not classified as asbestos paint suppliers. The high compara-
tive price value for the product appears to result from the much higher unit
value for the products given by the industry. As in the case of other asbestos
products, the explanation is probably due to use of retail prices in the indus-
try estimate and lower production cost values that the Bureau of Census reports.
On the basis of unit value used in the Bureau of Genus report, the forgoing
value of asbestos coatings and paints would be cut to about $20 million. This
is about 15-20% of the Bureau of Census value for all industrial maintenance
paints, SIC Codes 28516-11,13, of about $125 million in 1972.
15.2 Manufacturing Technology
The manufacture of coating and paint compounds consists simply of
thoroughly mixing batchwise fine dry asbestos fiber with bituminous vehicles,
such as asphalt and tar, along with a volatile solvent and other additives to
give specific properties to the bitumastic product. The asbestos concentration
ranges up to 10-12% in the product, depending on requirements for the applica-
tion (also refer to Section 9.2).
The overall operation consists in charging asbestos as received in
sealed bags into a storage-feeding system, measuring the asbestos into a batch
mixing tank where it is thoroughly blended and impregnated by the bituminous
solution. The product is discharged when finally mixed into metal containers
for delivery to the market. The principal shipments are in 5-gallon sealed lid
pails (Daly et^ al., 1976). Smaller size pails, as well as drum and tank car
quantities, are also shipped.
244
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The scale of the operations covers a wide range in annual capacities,
up to about 3 million gallons, and .in batch units up to several thousand gal-
lons.
No waste process water is produced. The only water used is for
washing purposes. Atmospheric contamination, which is potentially possible
from the bag emptying step, is controlled by ventilation with dust collection
bag filters. The collected dust is recycled to the feed. No scrap material is
produced.
The production facilities for the coating, painting, and sealant
products are the same as for roof coatings (Section 9), except that they are
usually at a significantly lower market requirement (as previously discussed).
Consequently, the coating operation will usually operate on a part-time basis
with the roof coating products, as well as with other non-ssbestos containing
coatings.
15.3 Asbestos Released to the Environment During Manufacture
Release of asbestos to the environment during the manufacture of
coating and paint compounds will normally be only that entrained with air
emitted from bag filters. No significant scrap or water effluents are pro-
duced. The asbestos released from bag filter emission can be approximated as
in Table 9.3, at a maximum of less than 1 ton per year, on average, for the
entire coating and paint compound production operations. The dust from bag
filters is the only release in which fibers are in free-fiber form. In other
effluents from washing, floor spills, and in wastage of the bitumastic product,
the asbestos fibers are encapsulated in the binder. Emission control techni-
ques are outlined fully in EPA (1973) publication.
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15.4 Asbestos Released to the Environment During Uses
Release of asbestos to the environment during use will occur from the
following sources:
1) Wastes during application;
2) Losses from weathering, wear, corrosion, etc. in services;
3) Scrap from maintenance, replacement, and from final demolition
of the structure or equipment.
In nearly all these losses the asbestos should be completely encased
in the bituminous binder. As a consequence, only small quantities of free-fiber
as airborne material are visualized.
One area of concern, in regards to release of free-fibers, is in
removal of texture paints containing asbestos. Sanding asbestos texture paint
to remove it from a wall may produce a serious health hazard (Anon., 1976d).
Any coatings or paints containing asbestos which are subjected to sanding or
similar physical forces will probably release free asbestos fibers which can be
inhaled. In this particular category, textured paints are probably the only
application in which removal by sanding is utilized; therefore, asbestos texture
paints are likely to present the greatest potential for free-fiber releases in
the coatings and paints classification. It should be noted that there is no
available monitoring data by which to quantify free-fiber releases from coatings
or paints.
It is possible that sales of asbestos texture paints may fall sharply
due to adverse publicity resulting from school closures in New Jersey in early
1977. A junior high school pupil was diagnosed to be suffering from a respira-
tory illness caused by inhaling asbestos particles at a school which was recently
246
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painted with asbestos paints to improve acoustics; as a result, the school
was closed to remove the asbestos (Anon., 1977b). It was later discovered that
the pupil was not suffering ftom asbestos exposure. However, such publicity
may certainly cause new buyers of texture paints to shy away from asbestos.
Unfortunately, some brands of texture paints which contain asbestos do not list
asbestos as an ingredient on the label (Anon., 1976c). Amended Air Control Act
of 1977 and guidelines given by EPA (1978) publication cover regulations for
these applications.
Considering the entire classification for coating and paint compounds,
it is Judged that an average of 1% of annual consumption is released as waste in
spillage, washings, and scraps during application. Scraps left in container
pails and some spillage are usually disposed to landfills, while some spillage
and washings may be disposed to municipal or plant sewer systems, from which
the asbestos particles would finally settle in deposits in the disposal system.
Losses of asbestos in service are judged from the usual maintenance
and replacement rates for industrial equipment, as in Section 12.4, to be
approximately 25% of the annual consumption. In the case of coating and paint
compounds, it is visualized that the losses resulting from oxidation, cracking,
and peeling of'the bituminous binder are in large pieces that are flushed off
by rain, spray, mechanical wear, corrosion, wear, or water condensate to floors,
ground, and surroundings. These may be washed away by the above processes in
ground water or spilled into process or municipal sewers or drainage systems.
Hence, the material collects as deposits in settling areas in the system. On
the above basis, the annual quantity front these sources is about 5000 tons per
year.
The asbestos contained in coating and paint compounds that would
usually be scrapped during replacements and demolition of the equipment and
247
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structure to which they are applied varies with the material. On steel equip-
ment, structures, piping, and other metallic material, the fate of the coating
is usually to scrap yards and recovery furnaces where the asbestos disappears as
slag from the charge. On demolished concrete and other non-recoverable materials,
the asbestos coatings are usually sent to landfill dumps or perhaps to incinerat-
ing operations. The fates of the material from these dispositions are covered
in earlier sections. The total quantity of asbestos released as scrap approxi-
mates the balance of annual consumption after 1% reduction for losses in appli-
cation, 1-2% consumed for expanding uses, and 25% in maintenance uses. This
equals about 70% or 14,000 tons per year. As an approximation, it is roughly
judged that 10,000 tons per year goes to landfill dumps and the balance (or
4000 tons) disappears in scrap recovery furnaces.
The above figures, which are summarized in Table 15.2, are based on
the 1976 consumption demand. These do not allow for the backlog that may pre-
vail from earlier consumption at higher rates. These past higher consumption
rates will tend to Increase the scrap rate for the near future.
15.5 Alternative Materials to Asbestos for Protective Coatings and Paints
The high strength, fineness, and structure of the asbestos fibers has
made it nearly impossible to substitute asbestos with an equivalent filler for
best quality coatings and paint compounds. As shown by Table 15.3, the tensile
strength of asbestos is much higher than for fibers of other spinnable materials.
Also, the fine fiber sizes and construction make asbestos unique in its property
to obtain high viscosity and thixotropic quality in the applied coated film.
These factors improve the life of the coatings with respect to weathering, with
less cracking and peeling away of the coating, and better adherence to the
protected surface.
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Table 15.2. Approximation of Asbestos Released to Environment from Coating
and Painting Compound Applications
Source
Disposition
Tons Per Year
Waste during application
To sewer system or landfills
200
Losses from wear,
weathering, and service
To sewer system or ground
waters
5,000
Scrap from replacement
and demolition
To scrap metal recovery 4,000
furnaces
To landfill and incineration 10,000
Total release 19,200
Note: Nearly all of the asbestos released in the above total is encapsulated
in the binders and is not in free-fiber form. Section 9.4 gives a
hypothetical example of fiber release from weathering effects, assuming
the fibers are in a free-fiber state.
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Table 15.3. Comparisons of Various Asbestos with Other Material (Clifton, 1975)
STRENGTH
Fiber
Crocldollte
Amoalte
Chryaotile
Class
Aluminum
Steel 5137
Tensile Strength
Young's Modulus
Kg/cm2
IS. 000
21,000
28.000
15,500
1.800
3.700
Lb/ln2 x 103
500
300
400
250
25.6
52.6
Kg/cm2
172.2 x 10*
153.3 x 10*
155.4 x 107
73.0 x 107
70.0 x 107
190.0 x 10*
Lb/ln2
24.6 x 10*
21.9 x 10°
22.2 x 10;
8.5 x 10;
9.9 x 10?
27.0 x 10
Specific Gravity
3.2
3.1
2.4
4.6
2.7
7.8
FIBER SIZE*
N>
Ot
O
(Asbestos Textiles, 1975)
llim.ui
R.ir.U-
Woo1.
Co: t o
K.«v.".'
X% ton
i* 1. 1**
SO.-K
A*>.-d
fype of Fiber
Hair
«
Wool
t.'s (Chrysotile)
Fiber Diameter
(inches)
0.00158
0.000985
0.0008 to 0.0011
0.0004
0.0003
0.0003
0.00026
0.000142 to 0.000284
0.000000706 to 0.00000118
Fibrils In One •
Linear Inch
630
1,015
910 to 1,250
2.500
3.300
3,300
3,840
3,520 to 7,040
850.000 to 1.400,000
* -.'..vaoUn Mining and Metallurgical Bulletin, April. 1951
SURFACE AREAS* (Asbestos Textiles, 1975)
Type of Fiber
Surface Area by N,, Adsorption
(aq. cm./gram)
Nylon
Acetate Rayon
Cotton
Silk
Wool
Viscose Rayon
Asbestos (Chrysotlle)
3.100
3.800
7.200
7.600
9.600
9,800
130,000 tc 220,000**
* Canadian Mining and Metallurgical Bulletin. April, 1951.
** Recent studies show that the maximum surface may run as
high ss 500,000 sq. cm./gram.
-------
There is no quantitative data for a firm economic evaluation of the
above improved properties. However, it can be reasoned that since the asbestos
content does not add to the Initial cost of the product as developed from con-
versations with suppliers, the increased life of the coating will not only give
a direct economic benefit in the cost of the coating material, but also a saving
in application costs which are in the same order as the cost of the material.
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16.0 ASBESTOS-REINFORCED PLASTICS
"Asbestos-reinforced plastics are polymeric materials to which
asbestos fibers are added in order to modify the composite's
physical and chemical characteristics. These composite materials
are multi-component blends in which the asbestos fiber is the
load-carrying member and the polymeric matrix fills the gaps
between the fiber and distributes the applied stress to the
fibers. The plastic material provides a shape and a smooth
surface to protect the fibers and may also provide thermal or
electrical resistance" (Daly e£ al., 1976).
Asbestos fibers have been used in combinations with plastics for more than
fifty years. The early applications in the 1920's were in asphalt floor tile,
phenolic-molding compositions, and asphalt coatings. These were followed by
vinyl-asbestos floor tile in the mid-19301s, and chemical-resistant equipment in
1933. Today, as in the past, the largest quantity of asbestos fiber used in
plastics consists of the shorter grades, which function as fillers as well as
reinforcing agents (Pundsack and Jackson, 1967).
The use of asbestos-reinforced plastics has expanded to products for the
electrical and aerospace fields, chemical-resistant pipe and process equipment,
friction materials, and thermoplastic molding and extrusion compounds. The
larger uses of asbestos-reinforced plastics, such as floor-tile, friction ma-
terials, and gasketing, have already been discussed in earlier sections of this
report. This section considers the other asbestos plastics uses, such as elec-
trical and process equipment, and thermoplastic molding and extrusion compounds,
as classified by the Bureau of Mines (Clifton, 1977). Additional data for all
asbestos plastics is also presented.
Asbestos fibers are used to reinforce phenolic, urea, melamine, unsaturated
polyesters, diallyl phthalate prepolymers, epoxies, silicones, polypropylene and
nylon (Seymour, 1975). Their industrial, commercial, and residential uses are as
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ubiquitous as the term "plastic" implies (Daly e_t aj,., 1976). A small example of
various asbestos-plastic products includes frying pan handles, nose cones for
missiles and rockets, electrical motor components, distributor caps in automobiles,
plastic molding components in automobiles, and corrosion-resistant pipe fittings,
valves, tanks, fume hoods, fume stacks, and scrubbers.
16.1 Use Quantity and Economic Data
In 1976, 21,500 tons of asbestos fibers were consumed in the production
of asbestos plastics as classified by the Bureau of Mines (Clifton, 1977). A
breakdown of the various chrysotile grades and crocidolite and anthophyllite
asbestoses used in 1976 is given below:
Short Tons
Chrysotile Grade 3 200
4 2,800
5 100
6 1,200
7 15,400
Crocidolite 700
Anthophyllite 1,100
Total 21,500
The crocidolite and anthophyllite varieties of asbestos are utilized for specialty
purposes where corrosion resistance is important, as their resistance to certain
forms of chemical attack is superior to chrysotile.
Listed below is a breakdown of all the asbestos-reinforced plastics
end-uses in 1976 (Clifton, 1977):
End-Use Asbestos Consumption (short tons)
Floor Tile 113,500
Friction Materials 63,800
Gasketing 6,000 (SRC estimate)
All other 21,500
Total 204,800
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Taken collectively, asbestos plastics are the second largest end-use of asbestos
fibers; only the collective addition of all asbestos paper uses ranks higher.
Reliable statistics on production of all types of reinforced plastics are dif-
ficult to obtain because a large percentage of producers are relatively small;
however, in 1966, it was estimated that the U.S. consumed over 1.5 million tons
of reinforcements and over 2 million tons of polymeric materials in producing
over 3.5 million tons of laminated and reinforced plastics (Grove and Rosato,
1967). In 1966, approximately 0.3 million tons of asbestos fibers were consumed
for plastic-type reinforcements (Clifton, 1975; SRC estimate); therefore, about
20% of all reinforced plastics in 1966 used asbestos fibers.
Statistics are not available for the current production of reinforced
plastics; however, according to USITC (annual), production of plastics and resins
had tripled from 1966 to 1976. Assuming a similar growth for reinforced plas-
tics, over 4.5 million tons of reinforcements were used to produce over 10.5 mil-
lion tons of reinforced plastics in 1976. From the above, about 0.2 million tons
of asbestos fibers were used as plastics reinforcements in 1976; therefore, only
4.5% of all reinforced plastics in 1976 used asbestos fibers. Glass fibers are
the most used reinforcing agents (Jenks, 1977). Asbestos plastics, as classified
by the Bureau of Mines, would comprise less than 1% of the reinforced plastics
market at present.
Consumption of asbestos for plastics reinforcement cannot be expected
to increase significantly in the near future. Consumption for flooring and
friction materials has fallen in recent years and a reversal of this trend is not
expected. The 1972 OSHA ruling limiting airborne asbestos concentration trig-
gered off a round of asbestos-free phenolic molding compounds by major producers
254
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(MacBride, 1976). General Electric, at that time, for example, eliminated
asbestos from their sizeable phenolic molding compounds production (Anon.,
1972).
The number of manufacturers of asbestos plastics, as classified by
the Bureau of Mines, is not readily available. A survey of the asbestos
industry by Daly et al. (1976) estimated that the five asbestos-reinforced
plastics plants surveyed used about 55% of the asbestos fiber in this classi-
fication. The Modern Plastics Encyclopedia (1977) lists two suppliers of
asbestos-reinforced molding compounds: Rogers Corp. (Rogers, Conn.) and
Plastics Engineering Co. (Sheboygan, Wise.). The Rogers Corp. has a large
plant which produces asbestos plastics in Manchester, Conn. (MacBride, 1976).
The cost of asbestos plastics can vary widely; for example, the cost
of asbestos-phenolic resin products can range from $0.60/lb to $5.00/lb
(Pundsack and Jackson, 1967). By current standards, the annual sales of
asbestos plastics, as classified by the Bureau of Census, is probably on the
order of $100 million (SRC estimate).
16.2 Manufacturing Process Technology
Figure 16.1 illustrates the general process flow for the manufacture
. of asbestos-reinforced plastics as classified by the Bureau of Mines. The
asbestos fibers are introduced into a dry blending step which involves mixing
the dry ingredients necessary to compound the material. Dry blending is needed
to achieve a homogenous mixture of the ingredients which include asbestos
fiber, catalysts, additives, resins, and polymers. A wide variety of equipment
is used throughout the industry to insure a low-shear, well-mixed blend. The
amount of asbestos present in the mix varies with the requirements of the final
255
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FIBER RECEIVING
AND STORAGE
FIBER INTRODUCTION
DUST COLLECTION
DRY BLENDING
DUST COLLECTION
RESIN FORMATION
KNEADING, ROLLING,
PRESS FORMING, MOLDING
CURE
FINISHING
I
DUST COLLECTION
CONSUMER
Figure 16.1. General Process Flow for Manufacture of Asbestos-Reinforced Plastics
(adapted from Daly et_ al., 1976)
256
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product. Some phenolic molding compounds contain 50-60% asbestos, while other
resin products may contain as little as 5% asbestos; an average asbestos con-
tent of 20-30% appears to be most common.
From the blending step, the mixture is then formed into a resin.
Some manufacturers refer to this step as a "preforming" operation in which the
mixture is heated by steam or electricity as in extrusion, or by internal
shearing friction as in a Banbury mixer. The product from these operations is
a pellet, powder, or some similar "preform" which is either packaged and sold
as an intermediate product or conveyed directly to a type of forming process.
"The forming step involves actual formation of an end product
from the preformed resin. The polymer portion of the resin
is the shape-forming ingredient of the preform. The final
product is shaped by remelting the preform and submitting it
to rolling, stamping, pressing, or molding. Remelting serves
to start the polymerization, cross-linking, and thermosetting
reactions; forming gives the desired shape of the end product"
(Daly et_ al., 1976).
"Following the molding process, the formed product is cured.
This step involves control of cross-linking and thermosetting
reactions to achieve specified strength and stiffness charac-
teristics. When the reactions are carried to their desired
ends, the rough product is then sent to a finishing step.
Finishing operations are similar to other asbestos industry
segments in that they involve sanding, grinding, polishing,
drilling, sawing, etc. The degree of finishing (e.g., rough
sanding vs. polishing) is dictated by product uses and the
variety of applications of these plastic materials" (Daly
et &1., 1976).
Although there are considerable variations to the asbestos-reinforced
plastics manufacturing steps, the above description is common to nearly all
products (Daly e£ al., 1976).
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16.3 Release of Asbestos to the Environment from Manufacture
Water is not used in the manufacture of asbestos-reinforced plastics,
except in the capacity of heat exchange fluid. As was the case for asbestos
floor tile, water does not come into contact with the asbestos-resin until the
product is inert, that is, the polymer matrix has been formed and the fibers are
tightly bound by the matrix. Therefore, there is virtually no release of asbes-
tos to the environment from process wastewaters. Asbestos would be released in
wastewaters from water-type air scrubbers which could be used to clean factory
air; however, baghouse collectors are normally used for this function. For
example, the Rogers Corp. plant in Manchester, Conn, is equipped with 10 baghouse
collectors handling air emissions containing asbestos fibers (MacBride, 1976).
The primary loss of asbestos from manufacture results from product
scraps, damaged products, and air and vacuum cleaning collections. Unfortu-
nately, there is no direct available monitoring data by which to quantify these
losses. However, it may be possible to quantify these losses by an indirect
method. In Section 6.6.1, it was estimated that approximately 12.7% of the
asbestos in friction materials manufacture was lost to all types of scraps. The
large bulk of this 12.7% loss resulted from grinding, trimming, and finishing of
the friction product. This kind of finishing is also done to the asbestos plas-
tics, as classified by the Bureau of Mines. Asbestos dust is released when these
plastic products are finished (Daly et^ al., 1976). Hand and portable tools are
normally supplied with local exhaust systems connected to the central ventila-
tion/collection system; in addition, work areas are connected to the ventila-
tion/collection system (Daly et_ al., 1976). The severity of dust release from
grinding, trimming, and finishing for asbestos plastics is not judged to be as
258
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great as for friction materials. Therefore, it is estimated that perhaps 6% of
production is lost to product scraps and baghouse collections, with baghouses
collecting perhaps two-thirds of this total. On a basis of an annual asbestos
usage of 21,500 tons, about 860 tons of asbestos would be collected by baghouses
and about 430 tons of asbestos would be contained in coarser product scraps.
The asbestos in the coarser product scraps is not recovered for reuse
because once the resin has set up, it is not regarded as economical to break it
down to salvage the fiber. Therefore, these scraps are removed to landfills and
waste dumps. Because the fibers are coated with polymeric materials, the release
of free-fibers to the environment is not likely.
The asbestos fines collected by baghouses are recyclable as a filler
material. At the Rogers Corp. Manchester plant, the accumulated fines are wetted
for reuse in beater operations (MacBride, 1976). Assuming the baghouses are
99.99% efficient, as described by Siebert e£ al. (1976), then about 0.086 tons of
free-fibers would be annually emitted to the atmosphere by baghouses. The alter-
native conversion factor developed in Section 7.3.1 would estimate this release
to be significantly higher.
According to the Rogers Corp., the only free-fibers of asbestos sent to
waste are contained in emptied bags, in which the fibers were shipped to the
factory (MacBride, 1976). Special precautions are taken to dispose of these bags
in landfills.
A summary of asbestos releases from plastics manufacture is given
below:
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Quantity (short tons) Comment
To water: none
To waste dump or landfill:
products scraps 430 Fibers coated with
polymer matrix
To air:
baghouse emissions <0.1 to ^ 1 Free-fibers
16.4 Fiber Release from Product Use
The diversified uses of asbestos-reinforced plastics complicate this
particular discussion. In general, most of these plastic products are not de-
signed to have a service life greatly in excess of ten years or so. Therefore, a
sizeable percentage of production is intended for replacement-type purposes. It
may be estimated that perhaps 80-90% of production goes for replacement purposes
(SRC estimate). The annual wasting of asbestos plastics may therefore be in the
range of 18,000 tons. These wastes will be disposed primarily to commerical
landfills and auto junkyards (asbestos plastics have significant usage in auto-
mobiles). Because the asbestos fibers are tightly bound in the plastic matrix,
the replacement wasting of asbestos plastics is not judged to cause any signifi-
cant free-fiber releases to the atmosphere.
During the service life of an asbestos plastic product, it is difficult
to envision any fiber release, due to the matrix bonding, unless the product is
subjected to friction, scraping, sanding, rubbing, or some other physical force
which could break down the plastic matrix. With the exception of friction ma-
terials, as discussed in Section 6.0, these forces are apparently not common to
asbestos plastics. Therefore, the actual use of most asbestos plastic products
would not seem to constitute any threat for free-fiber releases.
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It should be noted that monitoring data is not available for determining
potential free-fiber releases from asbestos plastics usage as classified by the
Bureau of Mines. Unless the particular product is commonly subject to some
physical force, such monitoring is probably not worthwhile.
16.5 Alternatives
A wide variety of alternative fibers to asbestos are available as
reinforcements and fillers in plastics. Such alternatives include carbon, ara-
nid, glass, fiberglas, hybrids, cellulose, ceramic, metallic, chemical, and
various mineral and synthetic fibers (Seymour, 1975). As discussed in Section 16.1,
the use of asbestos fibers for all types of plastics reinforcement has fallen in
recent years and is not likely to rebound. However, the reasons for this decline
can be attributed to use of alternative products and OSHA regulations causing
some manufacturers to stop using asbestos, but cannot be attributed to replace-
ment of the asbestos by a different fiber in most cases.
In earlier sections of this report, it has been stated that asbestos is
endowed with the useful characteristics of high strength, corrosion resistance,
high heat performance, and a comparatively low price. This cannot be said for
any available alternative fiber. However, if the intention of fiber reinforce-
ment is only for strength or only for corrosion (as examples), then asbestos is
not necessarily needed and is not, probably, commercially used at present. How-
ever, there are applications which require all of asbestos's characteristics.
According to the Rogers Corp., which decided to stick with asbestos reinforce-
ments despite OSHA regulations, high-heat performance and economic requirements
preclude the use of anything but asbestos as a filler system for phenolics,
particularly in the growth-potential automotive and appliance industries
(MacBride, 1976).
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17.0 MISCELLANEOUS ASBESTOS USES
This section discusses the various miscellaneous end-uses of asbestos fibers
in their particular applications and attempts to quantify use volumes and en-
vironmental releases where possible. The Bureau of Mines' end-use quantity
statistics for asbestos used throughout this report (Clifton, 1975, 1977) were
obtained by mail surveys of the major asbestos users, producers, and Importers
(Clifton, 1978). The survey questionnaire contained answer spaces for consump-
tion of the major end-uses as listed in Table 4.10. All other use consumptions
not specifically stated on the questionnaire were listed under a miscellaneous
classification. Therefore, the Bureau of Mines has absolutely no breakdown of
the uses listed under miscellaneous; the total asbestos fiber consumption of this
miscellaneous class in 1976 was 23,900 short tons (Clifton, 1977). A breakdown
of the various types and grades of asbestos used is the following (Clifton,
1977):
Chrysotile - Grade 3 300 short tons
Grade 4 800 short tons
Grade 5 2,500 short tons
Grade 6 4,400 short tons
Grade 7 14,700 short tons
Amosite 1,200 short tons
Table 17.1 lists the approximate quantities of asbestos fibers consumed in
specific miscellaneous end-uses as were available from literature and various
personal contacts.
It should be noted that the Bureau of Mines does not survey all users and
sellers of asbestos fiber, especially the small volume users or small volume
retailers. In this regard, the total consumption figures listed by the Bureau of
Mines are slightly less than might actually be the case. For example, "raw
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Table 17.1. Asbestos Consumption of Specific Miscellaneous End-Uses
End-Use
Consumption (short tons)
Year
Patching Compounds
Drilling Muds
Asphalt-Asbestos Cement
Shotgun Shell Base Wads
Fake Fireplace Ashes
10,000
10,000
< 100
500
5
1976 (Kearney, 1977)
1977 (Asbestos Infor-
mation Assoc.,
1978)
1977 (Koliber, 1978)
1974 (EPA, 197A)
1976 (SRC Estimate)
263
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asbestos is purchased by wholesalers and warehousers in 100-pound bags, repacked
in small quantities, and sold to retailers. These wholesalers repackage the
asbestos in 5- to 25-pound bags for resale. The ultimate customer may be a
plumber who uses the asbestos in a cement compound for repair of boiler or pipe
insulation" (Daly et^ al., 1976). The volume of asbestos used for these various
applications is virtually impossible to quantify. Also, what percentage of these
uses is included in the Bureau of Mines' figures is difficult to predict.
The following subsections discuss the various end-uses in the miscellaneous
category in terms of production, application, and environmental release.
17.1 Patching Compounds
An economic assessment of the patching compound market has been produced
by Kearney (1977) which gives an overview of the entire patching compound indus-
try. As a result of this study and other studies which concluded that patching
compounds containing asbestos pose health risks to consumers, the Consumer Product
Safety Commission has banned the consumer sales of patching compounds containing
asbestos (Anon., 1977c). However, the Consumer Products Safety Commission appar-
ently does not have jurisdiction over industrial applications of patching com-
pounds; for this reason, the production of asbestos patching compounds is con-
tinuing and will continue, according to various industrial spokesmen.
According to the Asbestos Information Association, about 10,000 tons of
asbestos were annually consumed in patching compounds (Kearney, 1977). The ban
imposed by the Consumer Product Safety Commission will effectively reduce this
consumption, but the degree of reduction is not certain at this time. In 1976,
Kearney (1977) estimated that 5-10% of annual sales were for purely industrial
applications; this would indicate that at least 500 to 1,000 tons of asbestos
will continue to be consumed in patching compounds.
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Approximately 50 firms have been identified as manufacturers of
patching compounds. Three major firms (Georgia Pacific, National Gypsum, and
U.S. Gypsum) produce nearly one-half of all patching compounds; however, none
of them claim to be using asbestos (Kearney, 1977). The annual value of all
patching compound shipments in 1976 was estimated to be roughly $120 million
(Kearney, 1977). Since about one-half of all patching compounds sold contain
asbestos (Anon., 1977c), or did contain asbestos, then perhaps sales of asbestos
patching compounds were roughly $60 million in 1976.
17.1.1 Application and Manufacture of Patching Compounds
Joint cements, or patching compounds, are used to finish the
installation of wall board for industry and home applications. The construction
industry and the do-it-yourself home installations use this material. Types of
patching compounds, by application, are listed in Table 17.2.
"There are two principal types of joint compounds. One
uses a latex or water-soluble glue as a binder and "sets"
by evaporation of the water. The other uses dehydrated
gypsum as the binder (and principal dry ingredient) and
sets by chemical reaction as the gypsum takes up water
of hydration. The first type is mainly limestone with
lesser amounts of mica and 3-5 percent asbestos. This
type is used in about 80 percent of the market, and is
mostly sold in the ready-mixed, wet form. The gypsum-
based material, with roughly 20 percent of the market,
also usually contains asbestos and must naturally be
sold dry and mixed just before use. The applicator
mixes the compound with water in the field. Wet-mix
products are manufactured and packaged in a can for
ready use" (Daly et^ al., 1976) .
"The manufacturing of joint cements incurs the common exposure
potentials for handling raw asbestos fibers when bags are stored, moved, slit,
dumped, and disposed of. The raw asbestos fiber is dry-blended or alternatively
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Table 17.2.
Types of "Patching Compound" by Application
(Kearney, 1977)
Types of
"Patching Compound"
Application
Patching plaster or spackle
(a generically used trade
name.)
Tape joint cement or compounds
used with a tape
This product includes
specialized drywall
formulations:
a. Taping formulation
b. Finishing
c. General purpose
b. and c. (Note: Currently,
texturing compounds labelled
as such, are not typically
used as "patching compounds")
Repair of small cracks and
imperfections in plaster
or gypsum wallboard interior
walls
Major repairing or finishing
of large interior wall cracks.
The most common application
is for covering the cracks
between newly erected drywall
panels
a. Applied in the first one
or two coats; designed
for strength
b. Applied in the final
coats; designed for a
quality finish with
minimal sanding
c. A compromise formulation
designed for both taping
and finishing; also often
used for small repair
applications (1 above)
Both b. and c. are also
often used as texturing
compounds to achieve
decorative wall and
celling finishes
266
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transferred to wet mixing before packaging" (Daly et^ al., 1976). The wet-mix
patching compounds are manufactured in a similar fashion as previously described
in other sections (9 and 15) of this report for mastic and bitumastic mixtures;
therefore, details are not included here.
"The product flows from the manufacturer, to wholesalers, to
retailers, to small contractors, and finally to appliers. The wet-mix product
has little potential for asbestos fiber exposure until it is finally applied and
allowed to dry. Sanding the product after it has dried can generate dust" (Daly
et al., 1976).
17.1.2 Environmental Asbestos Release from Manufacture
Patching compounds, or joint cements, are manufactured similarly
to asbestos-mastic or bitumastic mixtures. In this regard, the only environ-
mental release of free fibers will occur from baghouse emissions to the atmos-
phere and from wasted empty asbestos shipment bags. The Siebert et_ al. (1976)
baghouse efficiency of 99.99% would estimate baghouse releases to the atmosphere
to be less than 0.1 ton of fibers per year for the entire industry. Baghouse
collections of fibers can be recycled rather than wasted. Additionally, product
scraps are minor; cleaning and washing of equipment create only minor releases,
but in these releases, the fibers are encapsulated by the binder. There are no
wastewater releases of asbestos except, perhaps, in cleaning wastes.
17.1.3 Environmental Asbestos Release from Use
The Consumer Products Safety Commission has concluded that use of
patching compounds by consumers may constitute a health risk to the users (appli-
ers) and has, therefore, banned consumer sales of these compounds. According to
the CPSC, "asbestos fibers are released into the air after application, when the
267
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patching compound is sanded or scraped in the process of finishing or smoothing
the surface. Asbestos may also be released into the air when the dry form of
patching compound is mixed with water prior to use" (Anon., 1977c).
The fiber concentrations in air during use of patching compounds
are given in Table 17.3 from available monitoring data. Unfortunately, there is
not enough information available to precisely quantify these releases of free
fibers.
Product scraps left in supply containers may comprise roughly 1%
of production; these scraps, in which the asbestos fibers are encapsulated by
binders, are typically disposed to local landfills and garbage dumps.
The amount of patching material which requires sanding or scraping
depends upon the nature of the job and the proficiency of the applier. Assuming
that roughly 1% of production undergoes sanding or scraping, then about 100 tons
of scrap material (asbestos) are produced annually on a production basis of
10,000 tons. This scrap material, which does contain free-fiber asbestos, may be
disposed to* garbage dumps from floor sweepings or washed down drains to sewers or
rivers. The CPSC product ban will lower the above estimate because production
will be reduced; also, in the industrial areas of continued use, installations
should primarily be done by professional workers, which should cut down on waste.
Professional workers are also more likely to be equipped with tools which are
capable of collecting dusts generated by sanding, etc. via vacuum devices.
Asbestos dust and particles which may be collected (which could total in the
neighborhood of 10 tons annually on a 1,000 ton production basis) may require
special precautions for disposal, as the fiber could become airborne.
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Table 17.3. Asbestos Fiber Concentrations During Use of Patching,
Joint, and Tape Compounds (Rohl et^ a±., 1975)
Operations Number
of samples
Pole-sanding (1 to 1.5 m)
Background (2.5 m) , same room
Background (7.5 m) , adjacent room
Hand-sanding (1 to 1.5 m)
Background (2.5 m) , same room
Background (4.5 m) , adjacent room
Dry mixing (1 to 1.5 m)
Background (3 to 6m), same room
10
3
2
11
2
2
2
3
Background (5 to 10 m) , adjacent room 2
Sweeping floor (3 to 15 m)
15 Minutes after sweeping
35 Minutes after sweeping
1
1
Peak fiber concentration
(fibers per milliliter)
Mean
10.0
8.6
4.8
5.3
2.3
4.3
47.2
5.8
2.6
41.4
26.4
Range
1.2 to 19.3
3.5 to 19.8
0.7 to 8.8
1.3 to 16.9
2.1 to 2.5
1.5 to 7.1
35.4 to 59.0
0.5 to 13.1
2.1 to 3.1
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As is the case for most asbestos end-uses, the largest environ-
mental disposal of patching compounds occurs when products are replaced or
demolished. Service life-time may be for many years. In most of these replace-
ment scraps, the fibers should be bound in the binder; however, removal may cause
an undetermined percentage of the fibers to become airborne. Wetting according
to EPA demolition procedures should reduce airborne dust concentration. Re-
placement scraps are normally hauled to landfill sites for disposal.
17.1.4 Alternatives
Approximately one-half of all patching compound produced in 1976
did not contain asbestos. The percentage of non-asbestos patching compounds will
grow due to the CPSC ban. Therefore, asbestos replacement in these particular
compounds is not only theoretically possible, but is indeed a commercial reality.
However, many commercial users of non-asbestos patching compounds
believe them to be inferior to asbestos patching compounds.
"For commercial application, manufacturers consider asbestos to be
a critical constitutent which contributes to the workability and ease of appli-
cation of the compound and contributes to the appearance of the finished wall
joint. Efforts to substitute other materials for asbestos have generally re-
sulted in products considered by professional drywall finishers to be inferior in
performance and require more labor to use" (Kearney, 1977).
"Formulations are closely-held secrets and have been
developed after years of trial and error research and
experimentation. The few formulators who were willing
to discuss their work admitted a certain lack of under-
standing as to why asbestos uniquely seemed to impart
the qualities required for an efficient and durable
product" (Kearney, 1977).
270
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"Formulators who claimed to have identified satisfactory
substitutes for asbestos note that asbestos could not
be replaced with one ingredient. Rather, a complex of
several compounds was required to optimize the 10 to
15 desirable characteristics of a tape joint compound.
Workability (thixotropicity), water retention, decreased
need for sanding, and crack-free drying properties were
reported as extremely important. Further, these formu-
lators reported their asbestos-free products were fre-
quently more sensitive to variations of job-site tempera-
ture and humidity than their asbestos containing formula-
tions" (Kearney, 1977).
17.2 Drilling Muds
"Drilling fluids (muds) are essential for drilling oil and gas wells.
The use of asbestos in drilling muds is well-established and can have a signifi-
cant effect on lowering the cost of drilling and completing wells. Drilling muds
are pumped down through the drill pipe and back up the annulus between the drill
pipe and the well bore wall. When they arrive back on the surface, they flow
over a shaker screen to remove the drill bit cuttings, and into a mud pit. The
fluid is then recirculated through the hole. Materials needed to maintain the
properties of the drilling fluid are added in the surface pit" (Daly et_ al.,
1976)
"The main function of the drilling mud is to remove drill cuttings from
the hole and to contain formation pressures in the hole. The mud also removes
heat from the drilling action, acts as a lubricant, and prevents excessive hole
erosion. The drilling mud must be such that it remains fluid enough to be pumped
with minimum pump pressures. It must not be lost to the formation, yet it must
overcome formation pressures to prevent ingress of oil, gas, or water" (Daly
et al., 1976).
"Asbestos is added to the drilling mud to improve its carrying capacity
without appreciably increasing the viscosity. Other methods of improving the
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carrying capacity markedly increase viscosity, which increases pump pressures,
thus reducing the power available at the bit and slowing down drilling. Slow
drilling rates increase drilling costs. Asbestos is used in concentrations of
from 2-5 pounds per barrel (1 barrel = 42 gallons) of mud" (Daly «£ al., 1976).
"Asbestos is added to the drilling fluid through a mud hopper or large
funnel. Initially, a volume of mud of from 150 to 200 barrels is prepared. As
drilling progresses, additions are made to the system for maintenance and to
accomodate the volume of the hole being drilled. Typically, these conditions
occur only once during an 8-hour shift. The amounts of asbestos added are
small — rarely exceeding 500 pounds at a time" (Daly et^ al., 1976).
"Over 30,000 wells are drilled per year in the U.S., using around
1,500 drilling rigs. The frequent moving from site to site makes fixed control
equipment for asbestos fiber exposure infeasible. A normal drilling crew con-
sists of four men working an 8-hour shift; that is, three 8-hour crews per day.
Drilling sites may be miles from any population center and are subject to ex-
tremes of climatic conditions (for example, the north coast of Alaska to the Gulf
of Mexico)" (Dalye^al., 1976).
According to the Asbestos Information Association (AIA), the quantity
of asbestos fiber annually consumed for drilling fluids is approximately 10,000 tons.
The shorter grades of chrysotile fibers are normally used; palletized fiber as
well as loose fiber can be utilized.
17.2.1 Environmental Emissions
Asbestos is added to the drilling fluid at the job site; there-
fore, manufacturing emissions, in the conventional meaning, are non-existent.
During the addition of asbestos to the drilling fluid, an undetermined quantity
272
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of fibers becomes airborne. Release may be partially dependent upon weather
conditions; for example, a greater number of fibers may be released during windy
weather. Once the fibers are encapsulated by the mud, however, airborne releases
are unlikely to occur. Also, use of pelletized asbestos should significantly
reduce airborne emissions. Lacking monitoring data, it is judged that perhaps
0.5% of the asbestos consumption for drilling fluids is lost during on-site
mixing, or roughly 50 tons per year. These releases will probably settle on the
ground or be washed by rain, etc. from the air and eventually become stabilized
in ground or river sediments.
When drilling fluid is used, mud pits are usually dug or set up
next to the drilling rig (see Figure 17.1). Discussions with drilling contrac-
tors indicate that when drilling operations have been completed, the mud is
usually dumped or left in the mud pit and covered over with dirt; a sort of on-
site landfill. Occasionally, the mud may be transported to a new drilling site
when the new site is nearby. Airborne release of asbestos fibers from drilling
muds would appear to be unlikely because the fibers are encapsulated.
17.2.2 Alternatives
Asbestos is added to drilling fluids to increase the density, to
improve viscosity, and to reduce whole fluid loss. Asbestos is apparently unique
in being able to add to all three of these characteristics of drilling fluids.
However, many other materials are commercially used to give these properties to
drilling fluids. Choice of drilling fluids is apparently determined by appli-
cation of the individual job, soil characteristics, materials being drilled for,
and cost-effectiveness. Asbestos apparently comprises less than 2% of all
drilling fluid materials (SRC estimate).
273
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Drilling hose
Standpipe
Pump
.Shale
shaker
Steel
mud
pits
Bit
Figure 17.1.
A Circulatory System for a Rotary Drilling Rig
(Huebotter and Gray, 1965)
274
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Barite (natural barium sulfate) is the most extensively used
material for increasing the density of drilling fluids (Huebotter and Gray,
1965). Materials used to control viscosities include bentonite, attapulgite,
organophilic clays, various polyelectrolytes and coagulants, and ferrochrome
lignosulfonate among others. Materials used to prevent whole fluid loss (that
is, to bridge and plug holes and cracks and to seal highly permeable soils and
rocks) include many substances, such as cottonseed hulls, mica, and various
granular, fibrous, and flaky type materials (Huebotter and Gray, 1975).
17.3 Asphalt-Asbestos Concrete
Asbestos i^.added to asphalt to give it greater strength and longer
wear life. An asbestos-asphalt aggregate mixture has occassionally been applied
as a thin topping layer to airport roadways, bridge decks, and street curbings.
In 1974, about 50 of the estimated 5,000 asphalt concrete plants in the United
States used asbestos in aggregate mixtures each year, and the total amount of
asbestos consumed by individual plants varied greatly from year to year (EPA,
1974). Approximately 4,500 short tons of asbestos fibers were consumed in 1974^
for the production of asphalt concrete (EPA, 1974). However, various environ-
mental restrictions applied to manufacturing plants and concerns about adverse
health effects of asbestos fibers have caused consumption of asbestos in asphalt
concrete to fall markedly since 1974. According to a spokesman for the National
Asphalt Paving Association (Koliber, 1978), current use of asbestos in asphalt
concretes is less than 100 tons per year. In the near future, it is likely that
this particular application of asbestos will no longer be used. It is the policy
of the National Asphalt Paving Assoication (NAPA) to discourage the use of as-
bestos in asphalt mixtures because asbestos does not improve the properties of
275
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the mixture enough to offset environmental considerations (Koliber, 1978).
Also, certain polyester fibers produced by DuPont can be substituted for
asbestos in this use and still make a useable and economically viable product
(Koliber, 1978).
17.3.1 Manufacturing and Emissions
In the manufacturing process, asbestos is mixed with dried
aggregate. After a short dry mixing time, hot liquid asphalt is added to the
asbestos-containing aggregate and thoroughly mixed (EPA, 1974). As is the case
for other asphalt, mastic, and bitumastic processes using asbestos, the only
source of environmental release of free-fibers from manufacturing occurs from
bag openings and disposals and dry mixing. Considering the current asbestos
consumption is less than 100 tons per year, emissions from baghouses or other
collection devices are probably very small. In any product scraps which may be
disposed, fibers are encapsulated by the asphalt mixture and cannot become air-
borne.
17.3.2 Emissions from Product Use
Asbestos-asphalt concrete toppings have been applied to bridge
decks, airport roadways, and street curbings. It is possible that normal auto-
mobile or airplane traffic using these surfaces may enable asbestos fibers to
become airborne from surface wear. An exact estimate of the quantity or
mileage of asbestos-asphalt concrete surfaces in current use is not available.
17.4 Shotgun Shell Base Wads
Only one shotgun shell manufacturing plant in the United States is
known to use commercial asbestos; that plant is located in Bridgeport, Conn.,
and is operated by Remington Arms Company (EPA, 1974). Personal contacts with
276
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Remington Arms' representatives indicate that asbestos is currently being used;
however, the exact annual use quantity was not available. In 1974, approxi-
mately 500 tons of asbestos were consumed for shotgun shell production (EPA,
1974). Current use is judged to be approximately the same.
"Asbestos is used to manufacture base wads for shotgun shells. The
asbestos is mixed with wood flour and wax, and then pressed into base wads.
The weight composition of the final mixture is about 54 percent wood flour,
36 percent asbestos, and 10 percent wax. Asbestos emissions can occur during
asbestos addition to the mixture, during mixing operations, and at the wad
presses. The emission points are vented to the outside air through particulate
collection devices" (EPA, 1974).
17.4.1 Manufacturing Emissions
Process water is not used during manufacturing; therefore, the
only asbestos which could be released in waste waters would result from clean-
ing operations. Such releases are judged to be minor. Product scrap wastes
are also judged to be minor.
The major source of emissions occurs from baghouse operations
and exhausts. During the course of a year using 500 tons of asbestos in
production, roughly one ton of asbestos fibers will be collected in the bag-
houses by assuming 0.2% of production in air vented to the collectors as was
assumed in Section 9.3.4 for a similar manufacturing operation. Baghouse
collections are recyclable. Emission quantities to the atmosphere from bag-
house exhausts are very small when the Siebert et al. (1976) baghouse effi-
ciency of 99.99% is applied.
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17.4.2 Use Emissions
When a shot gun shell is fired from a gun, the base wad is
normally expelled from the cartridge and is commonly fragmented into many
separate pieces. Monitoring data for asbestos fiber release is not available;
however, it may be possible that free fibers are released when a shotgun is
discharged with an asbestos-containing base wad.
17.4.3 Alternatives
Other shotgun shell manufacturers apparently do not use asbestos
in making base wads, so alternatives to asbestos for this application are com-
mercially available. The exact need'for asbestos in some base wads is not
clear.
17.5 Artificial Fireplace Ashes
In addition to asbestos joint cements, the Consumer Products Safety
Commission has banned the consumer sales of artificial fireplace ashes contain-
ing asbestos (Anon., 1977c). In mid-1977, manufacturers stopped producing
asbestos fireplace ash in anticipation of a consumer ban (Ray, 1977). This
should effectively eliminate this application of asbestos in the future.
Artificial fireplace ashes or emberizing materials are decorative,
simulated ashes and embers which are used in some gas-burning fireplace systems
to give the appearance of burning embers. They serve strictly a decorative
purpose. Artificial emberizing material is sprinkled on or glued to gas logs,
or sprinkled on fireplace floors (Ray, 1977).
Between 1971 and 1976, over 100,000 gas logs were reported sold which
were frosted or treated by consumers with asbestos-containing materials (Ray,
1977). During 1976, this would indicate that roughly 20,000 gas logs were
278
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asbestos-treated. Asbestos quantity per log would normally be less than half a
pound; therefore, in 1976, only about 5 tons of asbestos (chrysotile) were used
for artificial embers.
Substitute materials for asbestos in artificial embers have been
commercially developed and distributed. These substitutes include Cerafiber,
which is a synthetic fiber developed by Johns-Manvilie, as well as rock wool,
vermiculite, and mica (Ray, 1977).
17.6 Other Uses
Other notable uses of asbestos, which have not been classified in any
of the Bureau of Mines' major end-use categories, include formed or spray-on
insulations, artificial snows, and foundry sands.
Formed or spray-on type insulations containing asbestos have been
nearly phased out of current commercial productions (Section 12.1). However,
retail sales of asbestos fiber, in small quantity lots, are probably being used
for these purposes. ,
Artificial snows, for decorative purposes, are apparently no longer
being made with asbestos fibers. It can be assumed that health considerations
caused production to stop. Annual use quantities were probably quite small,
anyway.
Asbestos has been mixed into foundry sands for special mold applica-
tions. Discussions with local foundries have indicated that OSHA regulations
have virtually put an end to the use of asbestos in foundry sands. A very good
alternative to asbestos for its special applications, wollastonite, is now
being used. Wollastonite is a naturally occurring calcium silicate found in
metamorphic rocks.
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18.0 SUMMARY OF ASBESTOS END-USES AND EMISSIONS FROM MANUFACTURE AND PRODUCT USE
The quantity of asbestos used for various end-uses is presented in
Tables 4.9 and 4.10 and is also presented in the individual sections throughout
this report. For the most part, these quantitative figures have been deter-
mined by the Bureau of Mines (Clifton, 1977). As has been explained in indi-
vidual sections, some of the end-use categories, as presented by the Bureau of
Mines, are considered to overlap. For example, the roofing end-use contains
quantities of asbestos fibers used to make paper, asphalt coatings, A-C sheet,
and A-C shingles; asbestos textiles are grouped into the insulation, friction
materials, and gaskets and packing classes as well as its own class. Other
overlaps also occur.
Table 18,1 gives a breakdown of the quantities of raw asbestos fiber
consumed in the primary manufacturing operations; overlaps have been eliminated
to the best possible degree from available data. Table 18.1 is intended to
list the asbestos fiber usage by each segment of the asbestos industry. Daly
e£ al. (1976), in cooperation with the Asbestos Information Association, sur-
veyed the entire asbestos industry to determine the asbestos fiber usage of
each industry segment, among other data. Comparison of Table 18.1 and the
data tabulated by Daly et^ al. (1976) reveals good agreement; the percentage of
usage does not vary more than several percent for any classification. As can
be seen from Table 18.1, more than one-third of all raw asbestos fiber is used
to make paper.
18.1 Asbestos Emissions from Manufacturing
The estimated environmental disposals and releases of asbestos from
manufacturing are listed in Table 18.2. The estimates in Table 18.2 consider
280
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Table 18.1. Asbestos Fiber Usage for Each Industry Segment in 1976 (SRC
estimates; Clifton, 1977; various personal contacts)
Industry Segment
Paper
A-C Pipe
Flooring
A-C Sheet
Friction Materials
Coatings and Paints
Textiles
Plastics
Drilling Fluids
Joint Cements
Gaskets and Packing
Other
Total
Tons Consumed
260,600
140,000
113,500
55,000
54,200
38,000
26,200
21,500
10,000
10,000
5,200
**
733,200
Percent of U.S.
Asbestos Usage
35.5
19.1
15.4
7.5
7.4
5.2
3.6
2.9
1.4
1.4
0.7
**
Undetermined, but probably less than five thousand tons.
281
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Table 18.2. Environmental Disposals and Releases of Asbestos from Manufacturing
(quantities in short tons)
ho
00
Paper
A-C Pipe
Flooring
A-C Sheet
Friction Materials*
Coatings and Paints
Textiles*
Plastics
Drilling Fluids
Joint Cements
Gaskets and Packing
Amount Collected
in Baghouses***
1,173
737
227
210
6,100
75
150
860
0
20
10
Totals 9,562
Total Amount
to Landfills
or Waste Piles
2,380
11,897
**
3,408
8,137
**
<350
230
10,000
**
40
36,442
Amount in
Free-Fiber Form
to Landfills
or Waste Piles
**
737
**
210
6,100
**
150
**
**
**
**
7,197
Amount
in Wastewaters
to Surface Waters •
46-98
11-12.5
**
3.8
0.3
**
**
**
**
**
**
61.1-114.6
**
***
Textiles used in making friction materials are listed in friction material collections and releases;
no other overlapping data is included.
Relatively very small quantities.
See text for amount of free-fibers released from baghouses.
-------
the primary manufacturers and most of the secondary manufacturers. The esti-
mates were extracted from Sections 6.0 through 17.0 of this report; the methods
describing how the estimates were made are given in those sections. As was the
case for Table 18.1, Table 18.2 consolidates estimates for the various industry
segments; for example, the release and disposal estimates for paper can be
obtained by adding the individual estimates for paper in the roofing, paper,
gaskets and packing, and insulation sections. It should be noted that most of
the estimates were derived from engineering assumptions and not from direct
monitoring data. Direct monitoring data were available for A-C pipe (Harwood
and Ase, 1977). Indirect monitoring data was available for friction materials
(Jacko and DuCharme, 1973; EPA, 1974) and for wastewater effluents from various
industry segments (Carton, 1974; Stewart et aJL., 1976).
Although the estimates in Table 18.2 appear to be rather exact
quantities, they should definitely not be considered as such. At best, these
estimates should be considered as "ballpark" figures.* The generation of pre-
cise release estimates would require a vigorous and extensive monitoring pro-
gram which has not been conducted to date.
Manufacturing emissions can, of course, be released to land, water,
or air. Table 18.2 estimates that in the neighborhood of 5% of the total
amount of asbestos consumed by manufacturing in 1976 was disposed to landfills
or waste piles, and of this amount, perhaps one-fifth was in free-fiber or
potentially respirable fiber form. Most of this free-fiber asbestos disposed
to landfills was generated by baghouse collection and then disposal; also
included in this quantity is free-fiber asbestos collected and disposed from
vacuum cleaning type devices. Disposal methods of these baghouse collections
283
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vary from plant to plant; in some plants, the collections are apparently dumped
on a waste pile with no further treatment while other plants may bag and bury
these wastes. The method of disposal will obviously affect the potential for
the free-fibers to become airborne. However, in perhaps four-fifths of the
amount of asbestos wasted to landfills and waste piles, the asbestos fibers are
tightly bound in some sort of matrix binder such as cement, asphalt, plastic,
or resins. It is unlikely that free-fiber asbestos is released to become
airborne from this matrix unless the scraps are crushed or incinerated or acted
upon by some similar physical force. This is apparently not the case, when
considering manufacturing wastes, with the exception of A-C pipe as detailed in
Section 7.0. It is visualized, for the most part, that the matrix bound asbes-
tos wastes will eventually become stabilized in the ground sediment of the
landfills or waste piles and be virtually unable to contaminate the air with
free-fiber asbestos. Ground waters may be able to leach fibers from some
products which are matrix bound; however, there is no monitoring data which
would suggest this action. Ground waters may be able to leach free-fiber
asbestos from waste piles or landfills if they are not contained in some pre-
cautionary manner.
The amount of asbestos released to surface waters from manufacturing
wastewaters is estimated in Table 18.2 to be roughly 100 tons annually. This
estimate is, of course, dependent upon the efficiency of clarifying equipment
at each individual manufacturing location. The results in Table 18.2 tend to
agree with Stewart's e_t al_. (1976) finding that "plants manufacturing asbestos
paper present the greatest potential for contamination of surface waters by
asbestos." It should be pointed out, however, that Stewart e£ al. (1976)
284
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monitored relatively high asbestos concentrations upstream as well as down-
stream from plant discharge points. At times the water entering the paper
plant was as contaminated with asbestos as when it left. It has been specula-
ted that ground outcroppings of asbestos, which are rained on or passed over by
ground or surface waters, contribute to the contamination of surface waters by
asbestos. Possible areas of naturally occurring asbestos deposits in the U.S.
are shown in Figure 5.1. It is impossible to try to quantify this potential
contamination at this time. Recycling of wastewaters has already begun at many
asbestos manufacturing locations. As wastewater recycling becomes more common
or technically feasible, surface water contamination by manufacturers will
become less significant. At this time it is not possible to say that asbestos
manufacturing wastes contaminate surface waters more than naturally occurring
asbestos ground formations.
The most important mode of asbestos release to consider is release of
free-fibers to the air. From the manufacturing process, emissions from bag-
houses or other air cleaning devices represent the greatest potential for
airborne release of asbestos fibers in free-form. Table 18.2 estimates that in
the neighborhood of 10,000 tons per year are collected in baghouses industry-
wide. As previously explained, these collections are either wasted to land-
fills or waste piles or recycled back to the manufacturing operations. Siebert
e_t al. (1976) has monitored the efficiency of baghouses, with regards to atmos-
pheric emissions, as nearly 99.99%. This would indicate that only 0.01% of
baghouse collection would be exhausted to the atmosphere. On the basis of
10,000 tons of collection, about one ton of free-fiber asbestos emissions are
released from all asbestos manufacturing plants nationwide using the Siebert
efficiency factor. This assumes that all plants use baghouses, which is not
285
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necessarily true. Although most plants do use baghouses, a few plants in the
past have used air scrubbers and may not have converted to baghouse filters.
Section 6.6 estimated that perhaps between 0.1 and 0.2 tons of free-fibers are
emitted to the air each year from air scrubbers in the friction material plants.
The accuracy of this figure is not certain. Also, the accuracy of applying the
Siebert baghouse efficiency of 99.99% to all baghouses industrywide is not
certain. In Section 7.3.1, a baghouse emission factor of 1.34 Ibs of asbestos
fiber emitted per year per 100 CFM rating was developed. For the various rea-
sons given in Section 7.3.1, this factor is probably higher than is the actual
case. However, it still appears valid to use such a factor because it was
developed from monitoring data; Siebert e£ al. (1976) monitored the typical
89 3
outlet concentration of a baghouse to be on the order of 10 -10 fibers/m (for
fibers > 0.06 ym) and 105-107 fibers/m3 (for fibers >_ 1.5 ym).
According to the 1972 Census of Manufacturers (Bureau of the Census),
there are about 140 asbestos manufacturing establishments in the U.S. Assuming
the ventilation exhaust capacity of these 140 plants averages 50,000 CFM, then
the total exhaust industrywide would be 7 x 10 CFM. The emission factor of
1.34 Ibs per 100 CFM rating would indicate that roughly 47 tons of asbestos
fibers are annually emitted by baghouses. This is a "worst possible" estimate.
It should be noted that both estimates of baghouse emissions, one ton and
47 tons, are developed from monitoring data of baghouses which are operating
with best practical efficiency. Faulty baghouse equipment or operation can
potentially cause significant emissions. Without continual monitoring data
from each individual asbestos plant, it is impossible to be more precise on the
amount of asbestos emitted by air cleaning devices collectively.
286
-------
The 99.99% efficiency factor implies that atmospheric emissions from
baghouses are proportionally related to the quantity of asbestos fiber collected.
This would indicate that the baghouses which collect the most material would
release the most emissions. On this basis, friction material manufacturers
would be responsible for nearly two-thirds of all baghouse emissions of asbes-
tos. Siebert et al. (1976) monitoring data also indicates that the amount of
baghouse emissions is related to .the volume of exhaust air. This would indi-
cate that the higher the CFM utilization on a baghouse, the higher would be the
mass of fibers emitted. Because of the cleaning requirements from dust genera-
tions, it is judged that friction material plants require the greatest CFM
volume from baghouses. In terms of air contamination from air cleaning de-
vices, friction material plants are apparently responsible for the largest
quantities of asbestos fibers being emitted to the atmosphere from any industry
segment.
18.2 Asbestos Emissions from Product Use
Monitoring data are available which indicate that asbestos fibers are
released from the normal use of asbestos-containing friction materials (Jacko
and DuCharme, 1973; Alste e£ al., 1976; Rohl e£ al., 1976, 1977) and from the
normal use of A-C pipe under certain conditions (Kuschner et_ al., 1974; Hallenbeck
et^ al., 1977; Buelow et, al^ , 1977; Craun e£ al., 1977). There is also monitor-
ing data available to indicate that fibers are released from use of asbestos
filters (Nicholson e£ al., 1973; Biles and Emerson, 1968; Wylie, 1974; Wehman
and Plantholt, 1974). Common installation procedures of asbestos patching
compounds have been found to release asbestos fibers (Rohl et_ al., 1975).
However, with the exception of the above examples and perhaps a very few
287
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others, asbestos release from normal product use of the estimated 3,000 asbes-
tos products has not been monitored.
At this time, the only use of asbestos products which appears to
release potentially significant weight units of free-fibers to the general
environment is friction material applications. It should be noted that the
evidence is inconclusive as to whether asbestos emissions from brake linings
have any biological significance. The use of A-C pipe and filters apparently
does not release sizeable weight amounts of fibers; however, the concentrations
which are released from these uses have caused concerns about adverse health
effects because they are released in areas where humans are exposed.
From Section 6.4.2, asbestos emissions from friction materials in
vehicles have been estimated to range from 79 tons (using Jacko and DuCharme,
1973, figures) (of which about 2.5 tons become airborne) to 1710 tons (of which
about 55 tons become airborne). The latter estimate is made from the Rohl
et £l. (1976) average of 4.5% median asbestos content in wear debris. It may
be noteworthy that this amount of asbestos estimated to be emitted to the air
from friction material use is higher than the amount of asbestos estimated to
be emitted from all industry manufacturing baghouse releases.
18.3 Asbestos Emissions from Product Disposal
As has been explained in the various product sections throughout this
report, a certain fraction of current production is destined for product re-
placements. Additionally, worn-out or damaged products containing asbestos are
removed from their use and disposed of, primarily to municipal dumps and land-
fills. It can be estimated that upwards of several hundred thousand tons of
asbestos, contained in the many products, are annually disposed to municipal
dumps and landfills.
288
-------
For the most partv the asbestos fibers in these disposals are bound
in some sort of matrix system, whether it be cement, plastic, or asphalt. As
indicated earlier, unless these wastes are crushed or incinerated, it is dif-
ficult to visualize any significant release of free-fiber asbestos. Demolition
operations, especially to friable asbestos products, can release free fibers
(EPA, 1974). The amount of asbestos released from demolition operations cannot
be satisfactorily quantified on a tonnage basis because enough data is not
available.
Carlin (1977) has estimated that of the asbestos products disposed to
municipal dumps or landfills, approximately 9% is destined for incineration;
the remainder is covered by landfill. Carlin (1977) has additionally estimated
that incinceration of asbestos products annually emits about 220 short tons of
free-fiber asbestos from all municipal incinerators. The accuracy of this
estimate is not certain; Carlin used many assumptions to arrive at his esti-
mate. Carlin (1977) concluded that asbestos air pollution from municipal in-
cinerators amounts to hardly 5% of the total emissions from all mining, milling,
fabrication, and disposal operations; and, in addition, that incinerators could
be significant, but far from predominant, in causing asbestos air pollution in
the United States. However, according to the findings of our current report,
Carlin's estimate of 220 tons of emissions would make incineration one of the
worst emission sources of free-fiber asbestos to air.
The ability of asbestos to survive municipal incineration has been
questioned by several asbestos industry spokesmen. The temperature of a properly
operating municipal incinerator should range from 1400-1800°F (Ross, 1970). At
about 900°F, chrysotile asbestos decomposes into a different mineral form
(Lynch, 1968) such as olivine. Therefore, most of the asbestos fiber should be
289
-------
destroyed by decomposition. However, amphibole asbestos fibers could poten-
tially survive incineration with minor alterations and still be in a biologi-
cally active form. Field check is warranted to determine if, and how much,
asbestos is environmentally released by incineration.
Asbestos products which are contained in landfills may be subject to
leaching by groundwaters. It would seem unlikely, however, that asbestos fibers
could penetrate any distance through soil unless there were a significant
number of cracks and fissures. A study to determine potential asbestos leach-
ing has apparently never been conducted. This type of study may be desireable.
290
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19.0 SOURCES OF ASBESTOS OTHER THAN FROM ITS COMMERCIAL PRODUCTION AND USE
Rock types in which asbestos minerals might be encountered lie at or near
the surface of about 30-40% of the continental United States (Stewart e£ al.,
1977; Kuryvial et al., 1974); Figure 5.1 shows these possible areas. These
areas also include most of the economically important mineral deposits. Re-
covery of these minerals, therefore, produces a potential for the release of
asbestos fiber to the environment (Stewart e£ al., 1977). Kuryvial e£ al.
(1974) investigated 58 mining districts throughout the U.S. and found various
types of asbestiform minerals in 16 of the districts. Bronstein e£ ail. (1978)
identified chrysotile asbestos in wastewater sources from various ore mining
and coal mining operations. Chrysotile concentrations found by Bronstein et al.
(1978) are presented in Tables 19.1, 19.2, and 19.3.
At least three sources of inadvertent asbestos contamination, from sources
other than commercial production and use of asbestos, have been publicized in
recent years. These sources involve asbestos contamination of talc, disposal
of taconite tailings containing asbestos, and quarrying for road stones which
contain asbestos. This section gives a brief description of these sources.
19.1 Talc
Various types of asbestiform minerals are present in commercially
mined talc: anthophyllite accompanies talc mined in the Dadeville deposits of
Alabama (Wells, 1975); New York talc from St. Lawrence County is intimately
associated with tremolite; and some California talcs are laden with tremolite
(Mulryan, 1969). It should be noted that only the infrequently occurring fibrous
tremolite is considered to be a true asbestos. Wastewater effluents from a
talc mine in upstate New York were monitored to have asbestos concentrations
5 8
ranging from 10 to in excess of 10 fibers per liter (Stewart et^al., 1977).
291
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Table 19.1. Results of Screen Sample Analysis of Total Fiber and Chrysotile Asbestos
(Bronstein e£ al., 1978)
10
vo
ro
Facility
Alcoa
Asarco-Galena
Asarco-Galena
Kennecott-SLC
Kennecott-SLC
Kenneco t t-SLC
Kennecott-SLC
White pine
Anaconda-Bu t te
Anaconda-Butte
Bunker Hill
Hecla-Star
St. Joe-Edwards
Hanna-Butler
Republic
UCC-Uravan
Lucky McMining
Cotter-Schwartzwalder
Kerr-McGee
Placer-Amex
Me In tyre Development
Pine Creek-UCC
Mo ly corp-Ques t a
Ore
Al
Ag
Ag
Cu (02B)
Cu (04B)
Cu (06B)
Cu (08B)
Cu
Cu
Cu
Pb/Zn
Pb/Zn
Pb/Zn
Fe
Fe
U
U
U
U
Hg
Ti
W
Mo
Wastewater Source
Treated mine water
Treated mine water
Tailing pond effluent
Tailing pond effluent
Treatment plant effluent
Tailing pond effluent
Treatment plant effluent
Treatment system effluent
Tailing pond -effluent
Treated mine water
Treatment system effluent
Tailing pond effluent
Tailing pond effluent
Mine water settling pond
Tailing pond effluent
Effluent from mill settling pond
Treated mine water
Treated mine water
Treated mine water
Tailing pond recycle
Mill water to recycle
Treated mine water
Tailing pond effluent
Total Fiber
(fibers/liter)
1.4 x 109
5.7 x 107
2.1 x 109
4.3 x 109
1.5 x 107
3.7 x 107
4.9 x 109
8.2 x 106
1.2 x 109
7.2 x 107
4.1 x 108
1.6 x 109
3.4 x 10®
4.2 x 107
4.3 x 107
1.2 x 109
5.7 x 108
2.3 x 109
4.3 x 108
7.7 x 108
1.5 x 108
3.3 x 107
3.3 x 1010
Chrysotile
(fibers/liter)
2.0 x 108
1.1 x 106
1.8 x 108
6.7 x 108
7.8 x 105
8.2 x 106
7.7 x 107
5.5 x 105
3.0 x 108
8.2 x 106
4.1 x 107
<3.3 x 105
2.4 x 107
3.8 x 106
4.1 x 106
1.5 x 108
2.7 x 107
2.0 x 108
5.3 x 107
5.7 x 107
1.3 x 106
8.2 x 106
2.0 x 109
-------
Table 19.2. Results of Screen Sample Analysis of Total Fiber and Chrysotile Asbestos
(U.S. Steel - Geneva Mine) (Bronstein et al., 1978)
Sample Total Fiber Chrysotile
Facility (M58-XI-Coal) Wastewater Source (fibers/liter) (fibers/liter)
8 7
Geneva Mine 01B Wastewater Storage Tank 8.8 x 10 8.6 x 10
(E. Carbon, UT) Overflow
9 8
Geneva Mine 026 Carlson Pumps Discharge 1.3 x 10 1.4 x 10
(E. Carbon, UT) (Mlnewater)
8 7
Coal Preparation Plant 05B Settling Pond Decant 3.7 x 10 1.6 x 10
(Wellington, UT)
10 * 5
£ Corresponding Blank - 2.2 x 10 fibers/liter
Detection Limit - 3.3 x 105 fibers/liter
-------
Table 19.3. Results of Screen Sample Analysis
in Coal Mining (Bronstein et^ al.,
of Total Fiber and Chrysotile
1978)
Asbestos
Company /Mine
Duquense Light Co. /Warwick //2
North American Coal/Conemaugh #1
Central Ohio Coal Co . /Muskingum
Peabody Coal Co./Sunnyhill
Eastern Associated Coal Corp. /Joanne
Valley Camp Coal Co. /Mine #6
Bethlehem Mines Corp./Boone #131
Island Creek Coal/Pocahontas #3
Bethlehem Mines/Pike #26
Falcon Coal Co./Haddix Operations
Consolidation Coal/Matthews
Amex Coal Co./Ayshire
Island Creek Coal Co. /Hamilton #1
Peabody Coal Co. /Will Scarlet
Southwestern Illinois Coal Co. /Captain
Peabody Coal Co. /Bee Veer
Texas Utilities/Fairfield
Decker Coal Co. /Decker #1
Western Energy/Colstrip
National Mines Corp. /Isabella
Versar Code
NC-20
NC-21
NC-22
T-5
NC-14
PN-11
NC-15
NC-16
NC-11
NC-12
NC-17
NC-8
NC-10
NC-9
NC-7
NC-5
V-6
NC-1
NC-2
NC-19
Total Fiber
(fibers/liter)
1.2 x 109
7.3 x 107
8.6 x 107
1.4 x 107
5.5 x 108
3.4 x 107
1.3 x 108
4.1 x 1010
3.3 x 107
3.4 x 109
1.5 x 1010
1.9 x 109
1.8 x 1010
3.1 x 108
4.0 x 109
2.2 x 109
5.2 x 1010
5.1 x 107
5.2 x 109
2.1 x 109
Chrysotile
(fibers/liter)
2.7 x 108
6.6 x 106
3.7 x 106
3.1 x 106
1.2 x 107
7.8 x 105
5.4 x 106
7.5 x 108
1.6 x 106
1.0 x 108
1.9 x 105
1.9 x 105
1.9 x 105
3.4 x 106
3.9 x 107
2.0 x 107
8.3 x 108
1.9 x 105
1.4 x 108 "
5.7 x 107
-------
The Mount Sinai researchers, including Selikoff, Rohl, Langer, and
Nicholson, completed a talc study in late 1975 which identified asbestos in
commercial cosmetic preparations of talc in amounts ranging from 2-20% (Anon.,
1976e). The FDA, however, said that results of its 1975 survey of 76 commer-
cial cosmetic talc products did not find asbestos.
Mount Sinai discovered that talc used to coat short-grained rice may
I
also contain asbestos (Anon., 1976e). Merliss (1971) states that talc-coated
rice in Japan has asbestos present as a contaminant.
U.S. talc mines produce roughly 1.2 million tons of talc each year
(Wells, 1975). Because the amount of asbestos which may be present in some
talc ores varies from deposit to deposit, it is very difficult to estimate the
tonnage quantity of asbestos which may appear as a contaminate. It becomes
more difficult, if not impossible, to then attempt to estimate the quantity
which may become exposed or emitted to the environment. An extensive amount of
monitoring data would be required to make an accurate estimate. This type of
monitoring data does not exist at this time.
19.2 Taconite Wastes
Taconite is a hard, low-grade ore, containing only 25% of finely
dispersed iron in the form of hematite or magnetite. Years of research re-
sulted in the development of a practical process for the up-grading of magnetic
taconite for use by steelmakers. In brief, the process involves pulverization
of the taconite ore and a magnetic separation operation to make pellets which
contain 65% iron. About three tons of taconite ore are processed to produce
one ton of taconite concentrate pellets. The remaining two tons are waste
tailings of a siliceous nature (Schmitt et al^., 1977).
295
-------
The Reserve Mining case brought to national attention the contamina-
tion of Lake Superior with asbestos particles from taconite tailings. Since
1955 the Reserve Mining Company has been discharging about 67,000 tons of
tailings suspended in 2 million tons of water to Lake Superior each day (Anon.,
1977e). The tailings in this discharge contain trace amounts of several
metals, but mostly they contain billions of amphibole silicate (asbestiform)
fibers. The heavier fibers sink by the force of gravity to the bottom of the
lake, but the lighter, buoyant fibers travel with the prevailing currents to
Duluth, Minnesota and Superior, Wisconsin, to become part of these cities1
drinking water (Anon., 1977e). Monitoring of drinking water systems in this
region has yielded amphibole fiber counts of 0.02 to 12.4 million fibers/liter
via electron microscopy analysis (Fairless, 1977).
19.3 Rock Quarries
At the present time, the Environmental Protection Agency is in the
process of studying the crushed stone industry to determine the asbestos con-
tent of serpentinite rock at quarrying operations (Anon., 1977d). The con-
troversy over asbestos content of some crushed stones began when Rohl et al.
(1976) published results of a study of crushed serpentinite quarried in
Montgomery County, Maryland. The stone had been extensively used for paving
roads, parking lots, and driveways. Air samples taken in the vicinity of these
paved roads showed that some chrysotile concentrations were about 1,000 times
greater than those typically found in urban ambient air in the U.S. Monitored
concentrations in Montgomery County ranged from extremely low readings to
3 3
readings as high as 17 million fibers/m and 6400 ng/m (Anon., 1977d). As
noted in Section 6.4.2.1 of this report, normal urban concentrations of air-
3
borne asbestos are commonly less than 30 ng/m .
296
-------
It is impossible to attempt to quantify asbestos emissions from such
sources until a great deal more monitoring data is available.
19.4 Summary
Without quantitative estimates it is difficult to assess the poten-
tial environmental contamination by indirect asbestos sources relative to the
commercial asbestos industry. The commercial asbestos industry is restricted
in certain areas as to the emissions or concentrations of asbestos which may be
permitted by the EPA or by OSHA. With a few exceptions, such as Reserve Mining,
the sources of asbestos release other than the commercial asbestos industry,
are apparently not regulated for asbestos emissions. In this regard, the
potential of these sources to emit asbestos into the general environment
deserves a great deal more study; the data which is available is extremely
sparse.
297
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20.0 SUMMARY ASSESSMENT
This report has focused on the commercial manufacture and use of asbestos
products. It has attempted to quantify the amounts of asbestos fiber consumed
by each of the major end-use industry segments and has attempted to estimate
the quantities of asbestos which may be emitted to the environment from manu-
facturing and product use. For the most part, quantity emission estimates were
predicted from engineering assumptions and the relatively small amounts of
monitoring data which were applicable. The accuracy of the emission estimates
made in this report should be regarded a.s "ballpark" estimates at best. More
precise emission estimates for manufacturing and product uses require addi-
tional monitoring data of a rather extensive nature. Although the basic manu-
facturing operations within a particular industry segment are common to nearly
all of the individual factories, slight variations, especially in terms of
disposal techniques, can cause one factory to emit a much greater amount of
asbestos than another. A plant by plant monitoring program would be required
to predict a precise total amount of asbestos fiber released to the environment
from manufacturing. For the purposes of this report it was necessary to assume
average disposal methods and pollution abatement methods within a particular
industry segment. The estimates which have resulted from these assumptions are
at least helpful in describing the magnitude of possible emissions.
The greatest amount of airborne fibers directly released by asbestos
product manufacturers is judged to come from baghouse emissions. Although the
baghouses used in the asbestos industry have been determined to have an excep-
tional efficiency, a very large number of small fibers are emitted each year by
baghouse exhausts. An attempt to quantify baghouse emissions has resulted in
298
-------
estimates ranging from one to forty-seven tons per year. The highest value is
considered as a severest possible emission. The exact fate of airborne asbes-
tos fibers is not known with certainty. Whether the fibers remain airborne,
settle to the ground, or are washed from the air by precipitation may depend
upon particle size and other factors; however, there is nothing available in
the literature to quantitatively predict the result. From the available data
and estimates, it appears that plants manufacturing friction materials, par-
ticularly brake linings, are responsible for a significant portion of all
baghouse emissions from product manufacture. Certain disposal techniques of
free-fiber manufacturing wastes'may also contribute significant amounts of
free-fibers into ambient air. However, available monitoring data is not suf-
ficient to quantify these releases.
As far as asbestos emissions from use of asbestos products are concerned,
friction materials appear to be by far the most serious polluter of any of the
asbestos products. Estimates of annual airborne fiber emissions from brake
linings range from 2.5 to 55 tons, and this represents only about 3% of the
total brake emissions of asbestos. However, the evidence is inconclusive as
to whether the emission of asbestos from brake linings has any biological sig-
nificance.
Relatively small amounts of asbestos fibers are emitted by the use of some
asbestos-cement pipes, depending upon the quality of water being transported.
Water which is particularly acidic is susceptible to causing erosion from walls
of A-C pipe, thereby releasing fibers in concentrations as high as a million
fibers per liter of water. Because A-C pipes are extensively used to transport
drinking water in the United States, release of small quantities of fibers may
cause considerable concern. The potential threat to human health from the
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amounts of fibers which may be released by A-C pipes is beyond the scope of
this report. However, it should be noted that the proper use of A-C pipe, as
outlined by the American Water Works Association, releases only extremely small
amounts of fibers or none at all.
Two consumer uses of asbestos, which have been determined to expose humans
to dangerous levels of airborne fibers, have been banned by the Consumer
Products Safety Commission. These uses are patching compounds and artificial
fireplace embers.
For the most part, however, most asbestos containing products have not
been monitored for fiber release during use. In a very high percentage of
applications, the asbestos fibers are bound in a matrix system, such as
asphalt, cement, or plastic, which makes fiber emission extremely difficult
under normal use.
As this report has noted, asbestos is a unique and very useful fiber due
to its properties and characteristics. Asbestos is widely used not only be-
cause it is economical, but also because it is the best available material for
nearly all of its applications. Products made with asbestos serve a very
useful purpose in the American industrial and consumer market. It is unfor-
tunate that the most widely used consumer product containing asbestos, brake
linings in automobiles, is also one of the major identifiable sources of asbes-
tos fiber emission into ambient air. In present-day drum brake lining and
clutch facing use, asbestos presence is almost essential. No other fiber or
material performs the job requirements nearly as well as asbestos. In disc
brake pad area, steel fiber reinforced semimetallic friction materials have
enjoyed increased usage; in model year 1978 the projected usage is for M.7% of
the U.S. production of passenger cars and VL3% of light trucks (Jacko, 1978a).
300
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Semimetallic disc pads are specified for certain after-market replacements and
semimetallic brake blocks are also installed on heavy trucks as aftermarket
replacements to the original equipment materials which are asbestos-based.
Alternate materials have been tested and are considered inferior. In practical
terms, it will probably be a number of years before asbestos can be totally
eliminated from automobile brake linings, disc pads, and clutches. Replace-
ment of asbestos will be accompanied by cost penalties due to increased mater-
ial and processing costs.
Demolition of buildings containing asbestos has been shown to emit asbestos
fibers. Quantification of these emissions is not possible because necessary
monitoring data are not available. Therefore,, no comparison on the magnitudes
of releases in relation to asbestos manufacturing or product use can be made.
Likewise, the amounts of asbestos emitted by product disposals is diffi-
cult to estimate. The most serious consideration of the wasting of asbestos
products may be potential airborne emissions resulting from incineration. One
estimate of fiber emission from incineration is 220 tons per year. The accu-
racy of this figure is not certain. However, this estimate would make incin-
eration the largest single airborne polluter of asbestos fibers. The genera-
tion of monitoring data in this regard seems highly desirable.
The mining and milling of asbestos have only been briefly touched upon in
this report. The various U.S. mines and mills have been identified in Sec-
tion 5.0 and the respective productions have been listed. However, no esti-
mates have been made as to the quantities of asbestos fiber which may be
released to the environment from mining and milling operations. Therefore, it
is impossible to attempt to compare emissions from mining and milling versus
manufacturing or product use. Although mining and milling are generally
301
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considered to contribute more fibers into the environment than manufacturing
per unit of processed asbestos, it should be remembered that over 85% of the
asbestos consumed in this country is imported.
Asbestos fibers are also emitted by sources which are not directly con-
nected to the asbestos industry. Natural ground formations of asbestiform
minerals can apparently release fibers into rivers and ground waters; however,
the quantities or concentrations of asbestos which can be attributed to these
natural sources has not been determined at this time. Asbestiform minerals are
also present in some talc, taconite, and rock quarries which are commercially
mined in the United States. Available monitoring data indicate that asbestos
emissions from these sources may potentially create dangerous exposure levels
to humans. However, because quantitative emission estimates are not available
for these sources, it is not possible to compare asbestos product manufacturing
and use with them.
To summarize, asbestos fibers are emitted into the general environment
from a variety of sources. These sources include asbestos mining and milling,
asbestos product manufacturing operations, use of some asbestos-containing
products, disposal operations to various asbestos products, and varied mining
and natural sources. Sufficient data are not available to predict which of the
above sources are primarily responsible for the asbestos fibers which have been
monitored in general ambient air and potable water samples. Air monitoring in
localized areas has indicated that specific sources contribute significant
levels of asbestos into ambient air in that particular area. These specific
sources include crushed serpentinite stone containing serpentine asbestos used
to pave roads and driveways, demolition of buildings containing asbestos
302
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construction materials, and automotive brake linings adjacent to toll plazas
where cars brake to a stop. An extensive program of specialized monitoring is
required to determine, with any certainty, the degree of responsibility which
may rest with a potential emission source in terms of the total urban air
environment.
This report has, however, estimated a general magnitude of emission from
asbestos product manufacturing and from automotive brake lining use. It has
also identified municipal incineration as a potential source of significant
asbestos fiber emission to ambient air. It is probably reasonable to judge
that urban air levels of asbestos are caused by a combination of brake emis-
sions, municipal incineration, building demolition, and product manufacturing.
It is further judged that elimination of asbestos from brake linings could
significantly reduce urban air levels of asbestos.
303
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TECHNICAL REPORT DATA
(fleate read Iiatntctlum on the revcnc before completing)
1 REPORT NO.
EPA 560/6-78-005
2.
4. TITLE AND SUBTITLE
Chemical Market Input/Output Analysis of Asbestos to
Assess Sources of Environmental Contamination
3. RECIPIENT'S ACCESSION-NO.
S. REPORT DATE
August 1978
6. PERFORMING ORGANIZATION CODE
AUTHOR(S)
William M. Meylan, Philip H. Howard,
Sheldon S. Lande , Arnold Hanchett
8. PERFORMING ORGANIZATION REPORT NO
TR 77-515
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Center for Chemical Hazard Assessment
Syracuse Research Corp.
Merrill Lane
Syracuse, N.Y. 13210
10. PROGRAM ELEMENT NO.
li.C6KITRAcT/ORANTNO.
EPA 68-01-3224, Task III
12. SPONSORING AGENCY NAME AND ADDRESS
Office of Toxic Substances
U.S. Environmental Protection Agency
Washington, D.C. 20460
13. TYPE OF REPORT AND PERIOD COVERED
Final Report
14. SPONSORING AGENCY CODE
IS. SUPPLEMENTARY NOTES
ID. ABSTRACT
This report considers the sources of asbestos environmental contamination.
Marketing information, available monitoring data, and engineering assumptions were
used to estimate asbestos emissions. Chrysotile is the more common commercial
mineral form of asbestos, although others such as crocidollte, amosite, and
anthophyllite are also commercially important. Asbestos is used in thousands of
products including friction materials (brakes and clutches), asbestos-cement pipe
and sheet, roofing, paper, flooring, insulation, packing and gaskets, textiles,
coating and paints, and plastics. The available information would not allow for
any quantitative estimates and rarely was an ambient level attributable to a
particular source. Exceptions were crushed serpentinite rock containing asbestos
that was used to pave roads and driveways, demolition of buildings containing
asbestos construction material, and automotive brake linings adjacent to toll
plazas where cars brake to a stop. Municipal incineration may also be a potential
source of significant asbestos fiber emission to ambient air. Release of asbestos
fibers from A/C pipe used for drinking water appears to be minor, except where the
water is very aggressive.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
asbestos
chrysotile
crocidolite
brakes
A/C cement
roofing
18. DISTRIBUTION STATEMENT
Document is available to the public
through the National Technical Informa-
tion Service. Springfield. Va. 22151
b.IDENTIFIERS/OPEN ENDED TERMS
19. SECURITY CLASS (TillsReport)
20. SECURITY CLASS (TMt pagf)
c. COSATI I tcld/Croup
21. NO. OF PAC.es
323
22. PRICE
EPA Form 2X20-1 (»-73)
•U.S. GOVERNMENT PRINTING OFFICE: »7S J80-MO/1OT 1-S
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