Interior Coatings in
Potable Water Tanks
and Pipelines
Coal Tar Based Materials and
Their Alternatives
The MITRE Corporation
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DISCLAIMER
This report has been reviewed by the Office of Drinking Water,
U.S. Environmental Protection Agency, and approved for publication.
Approval does not signify that the contents necessarily reflect the
views and policies of the U.S. Environmental Protection Agency, nor
does mention of trade names or commercial products constitute en-
dorsement or recommendation for use*
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ABSTRACT
This report discusses the use of coal tar based coatings and
their alternatives as protective linings in potable water pipelines
and storage tanks. The report includes descriptions of the various
coatings, and presents information on their cost, extent of use, and
problems associated with their application.
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ACKNOWLEDGMENTS
The authors wish to express their appreciation to the following
persons at the Mitre Corporation for their most helpful suggestions
and assistance in preparation of this report: Dr. Lydia M. Thomas,
Dr. Stephen H. Lubore, Dr. Paul Clifford, and Pamela Miller. Special
thanks go to Mr. J.E. Carvlin and Mr. Henry Stoner and their col-
leagues at Koppers Company for their review and constructive comments.
We gratefully acknowledge the cooperation and courteousness of the
numerous persons in government and industry who responded to our
queries. Without their cooperation this report would not have been
possible.
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TABLE OF CONTENTS
Page
LIST OF TABLES vlii
GLOSSARY ix
EXECUTIVE SUMMARY xi
1.0 INTRODUCTION 1
2.0 COAL TAR BASED PRODUCTS 3
2.1 Coal Tar Based Coatings Used in the Potable 3
Water Supply Industry
2.1.1 Hot Applied Coal Tar Enamel 5
2.1.2 Cold Applied Coal Tar Paint 7
2.1.3 Cold Applied Tasteless and Odorless 8
Coal Tar Paint
2.1.4 Coal Tar Epoxy Paint 8
2.1.5 Coal Tar Urethane Paints 11
2.1.6 Coal Tar Emulsion Paint 11
2.2 Importance of Coal Tar Based Products to 12
Producing Industry
3.0 ALTERNATIVES TO THE USE OF COAL TAR BASED LININGS IN 15
POTABLE WATER DISTRIBUTION SYSTEMS
3.1 Water Supply Industry Preferences for Protective 24
Linings in the Water Distribution System
3.2 Comparison of the Cost of Alternative Protective 30
Lining Systems
4.0 UTILIZATION OF COATING MATERIALS 36
4.1 Application Methods 36
4.2 Problems Associated with the Application of 39
Coatings
5.0 TOXICOLOGICAL CONSIDERATION OF THE MATERIALS USED 44
AS LININGS
5.1 Compounds Identified in Potable Water and 45
Attributed to the Use of Lining Materials
5.2 Amelioration of Potential Toxicological 53
Problems
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TABLE OF CONTENTS
6.0 CONCLUSION AND RECOMMENDATIONS
BIBLIOGRAPHY
APPENDIX A DESCRIPTION OF NON-COAL TAR BASED
LINING SYSTEMS
APPENDIX B TYPICAL COATING CHARACTERISTICS
APPENDIX C FDA LIST OF APPROVED POTABLE WATER
TANK LININGS
APPENDIX D APPLICATION PROCEDURES FOR PIPE AND TANK
LININGS
APPENDIX E DIRECTIONS FOR DETERMINING THE WATER
EXTRACTABLE SUBSTANCES FROM A POLYMERIC
OR RESINOUS WATER CONTACT SURFACE
Page
54
56
65
75
93
101
119
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LIST OF TABLES
Page
Table Number
2-1 PARTIAL LIST OF MANUFACTURERS OF COAL 14
TAR BASED PAINTS
3-1 COMPARISON OF ALTERNATIVE WATER SYSTEM 20
LININGS WITH RESPECT TO SELECTED VARIABLES
AFFECTING THEIR USE
3-2 PIPE USED IN U.S. WATER SUPPLY DISTRIBUTION 23
SYSTEMS BY UTILITIES SERVING OVER 2,500
PERSONS
3-3 COMPARISON OF THE COST OF CONSTRUCTION OF 25
WATER TANKS BY MATERIAL OF CONSTRUCTION
3-4 TABULATION OF VARIOUS ESTIMATES OF THE 29
PERCENTAGE OF NEW WATER TANKS LINED WITH
A GIVEN PAINT SYSTEM
3-5 ESTIMATES OF THE COST OF APPLYING SELECTED 31
LININGS TO POTABLE WATER TANKS BY SOURCE
3-6 COST ESTIMATES FOR APPLYING SELECTED LININGS 32
TO POTABLE WATER TANKS
4-1 BLOWER CAPACITIES REQUIRED TO MAINTAIN VAPOR 41
CONCENTRATION WELL BELOW LOWER EXPLOSIVE
LIMIT
5-1 ESTIMATED CONCENTRATIONS OF COMPOUNDS 46
DETECTED IN THE WATER IN THE BAYOU CASOTTE
GROUND STORAGE WATER TANK
5-2 COMPOUNDS DETECTED IN THE WATER SAMPLES 49
OBTAINED IN PORTLAND, OREGON
5-3 ALTERNATE SOURCES OF THOSE COMPOUNDS IDENTIFIED 50
IN THE BAYOU CASOTTE GROUND STORAGE WATER TANK
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LIST OF TABLES
Page
Table Number
5-4 ATMOSPHERIC CONCENTRATIONS REPORTED FOR THOSE 51
COMPOUNDS IDENTIFIED IN THE BAYOU CASOTTE
GROUND STORAGE WATER TANK
5-5 QUALITATIVE AND QUANTITATIVE LEACHING 53
EVALUATIONS CURRENTLY IN PROGRESS
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GLOSSARY
Acronyms
AISI
ANSI
ASTM
AWWA
NACE
SPCC
American Iron and Steel Institute
American National Standards Institute
American Society for Testing and Materials
American Water Works Association
National Association of Corrosion Engineers
Steel Structures Painting Council
Barytes
Cathodic
protection
Coal tar
pitch
Destructive
distillation
Enamel
Fractional
distillation
A rippling appearance
A brown to black solid or semisolid mixture of non
paraffinic hydrocarbons which occur naturally and
which are also obtained as a residue from petroleum
refining processes
Barium sulfate
The use of direct current electricity from an external
source to oppose the discharge of corrosion current
A dark brown to black residue from the distillation of
coal tar ranging from a sticky mass to a brittle solid
depending on the degree of distillation
The heating of material such as wood, coal oil shale
and residual oil in an inert atmosphere at a tempera-
ture high enough for chemical decomposition
A paint that forms a smooth, glossy, hard coat when
applied
A process of separating components of a volatile
mixture by continuous counter current contact of a
liquid phase and a vapor phase so that the vapor
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Keystone
Light oil
Penetration
Pig
Slot-type
c oke oven
Softening
point
Talc
Thixotropic
phase is continuously enriched in the more volatile
component and the liquid phase is simultaneously
enriched in the less volatile component
Wedge-shaped pieces that form when a concrete lining
is cracked
A clear, yellow-brown oil somewhat lighter than water
and containing varying amounts of coal gas products
with boiling points ranging between 40°C and 200°C
A measure of hardness or softness of coal tar enamel
by ASTM test method D-5
A brush, swab, or scraper device that is pushed or
pulled through a pipe, usually for the purpose of
cleaning the pipe
A coke oven designed and operated to permit collec-
tion of the volatile material from coal during the
coking process and characterized by a narrow, long
and tall coking chamber
Temperature at which the viscosity of coal tar enamel
is 1 X 10^ centistokes when tested in accordance
with ASTM test method D-36
Hydrous magnesium silicate
The property exhibited by certain gels of becoming
liquid when stirred or shaken
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EXECUTIVE SUMMARY
Under the Food Drug and Cosmetic Act, the FDA has the respon-
sibility for determining the appropriateness of the use of materials
that contact food, which may include potable water; the U.S. Envir-
onmental Protection Agency (EPA) has been providing informal advice
regarding the suitability of coating materials used to line potable
water tanks and pipelines. Coal tar and petroleum based coatings are
widely used by the water supply industry to protect iron and steel
from corrosion. These coatings have been considered safe for contact
with potable water; however, increasing awareness of the presence of
trace organic contaminants in drinking water provided the impetus for
a reevaluation by the EPA of the suitability of these coatings for
this purpose. Mitre/Metrek was requested to provide some of the
background information which the EPA would need as input to an evalu-
ation of the safety of coatings used for potable water system contact
surfaces.
Coal tar coatings have been used in the United States to provide
corrosion protection to the interior of steel potable water pipelines
and to the interior of steel potable water storage tanks since 1912.
The coal tar coatings are made by combining coal tar pitch with other
material to make a coating with the properties desired for particular
service conditions. The pitch imparts the properties of water imper-
meability, good adhesion, and protection against attack by biological
organisms.
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There are two types of coal tar coatings, hot applied and cold
applied. The hot applied coating is formulated as an enamel by
combining the coal tar pitch with coal, coal tar base oil and talc.
By altering the proportions of the various ingredients, the proper-
ties of the coating can be adjusted to desired specifications. Cold
applied coal tar coatings are combinations of coal tar pitch and
suitable solvents or synthetic resins. The cold applied coal tar
coating systems include cold applied coal tar paint, cold applied
tasteless and odorless coal tar paint, coal tar epoxy, coal tar
urethane, and coal tar emulsion.
Hot applied coal tar enamel is widely used to protect the inter-
ior and exterior of buried water mains and the interiors of water
storage tanks. It is very durable, having a reported service life in
excess of 50 years. Thus, it requires very little maintenance. The
cold applied coal tar coatings are not as durable as the hot applied
enamel but are more convenient to apply. Therefore, they are often
used for above ground structures and the interiors of water storage
tanks where maintenance is less difficult.
Approximately 685,000 miles of water pipe have been installed
in the U.S. by those water utilities which serve a minimum of 2500
persons. A steady annual increase of approximately 2 percent in the
quantity of inservice piping is the result of new water pipe instal-
lation. Slightly less than 6 percent (i.e., 39,400 miles) of the
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water pipe that is currently installed is steel, and it is believed
that between 50 and 80 percent of this steel pipe is lined with hot
applied coal tar enamel. Other linings that have been used in steel
pipe are cement mortar, baked phenolic, polvinyl chloride, poly-
ethylene, vinylidene chloride copolymer, tetrafluoroethylene and
neoprene. Approximately 75 percent (on a mileage basis) of the
water pipe that is currently in place is cast iron, which is usually
lined with cement mortar. The cement mortar lining in cast iron pipe
is given a seal cost of bituminous material to aid in curing of the
cement mortar and to inhibit soft water decalcification. The
seal coat is usually a petroleum derived asphalt paint. Asbestos
cement pipe accounts for approximately 13 percent (on a mileage
basis) of water pipe in place. Materials used for the remaining
water pipe are reinforced concrete, plastic, iron, copper and wood.
There are approximately one-half million steel water storage
tanks in the U.S., ranging in capacity from 50,000 gallons to 10
million gallons. A number of different linings have been used to
protect the interior of these tanks from corrosion including
several which are coal tar based, and vinyl, epoxies, wax, zinc
rich, metallic zinc, chlorinated rubber, and phenolic based linings.
Over 1000 new steel water tanks are constructed each year.
Because conflicting estimates were obtained from industry contacts
of the percentage of these tanks being lined with coal tar based
coatings, no accurate estimates can be given. Koppers Company, the
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major supplier of coal tar coatings to the industry, estimates that
19 percent of new steel water tanks are lined with coal tar* In
some locations, 100 percent of the steel water tanks are lined with
hot applied coal tar enamel (Seattle, Washington; California Water
Service).
An estimated 10,000 tons of hot applied coal tar enamel, repre-
senting somewhat less than 10 percent of the total market for the
product, were sold to the water supply industry in 1976. The value
of the coal tar enamel to the producers was $1,500,000. The dollar
value of solvent based cold applied coal tar paint used in new water
supply industry construction in 1976 was about $225,000.
In recent years, the use of hot applied coal tar based linings
for water distribution systems has been declining. Shortages in the
availability of qualified applicators, Increasing costs, difficulties
in the ability to control worker exposures during application, and
increasing concern of the potential effects on human health have
all contributed to the decline in usage of hot applied coal tar
based materials for this purpose.
A variety of alternatives to the hot applied coal tar based
linings have been developed and are finding increasing application.
Cement mortar (not normally seal coated) or polyamide cured epoxy
paint are commonly used as alternatives to hot applied coal tar
enamel for lining steel water pipes. The AWWA standard for painting
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and repainting steel water storage tanks includes a number of non-
coal tar based systems (e.g., vinyl paints, metallic zinc, wax,
chlorinated rubber, and epoxy). In addition, there are numerous
proprietary paint formulations considered suitable for use in water
immersion service which have received approval for use as linings
in potable water storage tanks by local, state, and federal agencies.
Personal preferences and cost play a part in the selection of a
particular lining for water tanks. Many different linings are being
used nationally, however, some localities still prefer coal tar
enamels. Although the initial application cost of most of the
alternative coatings is comparable to that of hot applied coal tar
enamel, their life time cost (e.g., including maintenance and repairs)
ranges from 2.5 to 11.5 times that of the cost of coal tar enamel,
primarily due to the necessity for more frequent recoating.
Although it is apparent that obvious choices in a lining mate-
rial may be indicated by ease of application, frequency of need for
repair, and/or lifetime costs, there is no suitable and comprehensive
method for evaluating the relative health risks of the various avail-
able materials. Concern of risks to public health has escalated
with repeated determinations of the presence of organics in trace
quantities in potable water. There are data that provide evidence
for leaching of organics into water from coal tar based coatings used
for water system contact surfaces. The data are limited, however,
and are not Indicative of leaching rates, the constancy of those
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rates, the effects of water quality on leaching rates, the solubili-
ties of the leached compounds, the extent and products of decomposi-
tion of the leached compounds, the ultimate concentrations to which
the general public might be exposed via drinking water, or the
interactions between the compounds. Due to the inadequacies of the
data it is not possible to prudently estimate the relative health
risks inherent to the various materials utilized for potable water
system contact surfaces. In addition to the health risks to the
general public, there are occupational health risks associated with
application of the linings (e.g., vinyl paints may contain vinyl
chloride monomer a known carcinogen; urethane paints and epoxy paints
contain ingredients that are irritants to some people; exposure to
zinc oxide fumes during application of metallic zinc coatings can
cause metal fume fever; some materials contain solvents which are
central nervous system depressants).
New paint products and formulations are regularly introduced to
the market, and their suitability for use on potable water contact
surfaces is currently based primarily on durability under long-term
immersion conditions and the results of an extraction test. The
extraction test is not designed to qualitatively or quantitatively
determine the individual compounds that are leached into the water
nor does it provide values for the parameters of interest mentioned
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previously. Until such time as these data are available and applic-
able toxicological information is compiled it would be difficult to
proceed with a comprehensive assessment of the relative effective-
ness/risk of the various coatings.
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1.0 INTRODUCTION
Iron and steel are commonly used for potable water pipelines and
storage tanks. A surface coating is applied which will protect the
metal fro™ corrosive attack and reduce rust contamination of the
water. Since the coating is in contact with the potable water, it is
essential that it not impart any taste, odor or toxicity to the
water. The U.S. Environmental Protection Agency (EPA) has been
providing informal advice to states regarding the suitability of
substances which may directly or indirectly contact potable water.
Coal tar and petroleum based coatings are widely used by the water
supply Industry to protect iron and steel from corrosion and have
been considered to be safe for contact with potable water. However,
increasing concern about trace organic contaminants in drinking water
has caused the EPA to reevaluate the safety of these and other
coatings used in potable water distribution systems.
The EPA Office of Drinking Water requested Mitre/Metrek to
provide some of the background information needed to properly
evaluate the safety of various coating formulations used in potable
water distribution systems. In particular, information was requested
regarding the following:
a. Coal tar products used, the extent of their use, their cost,
and their Importance to the coal tar producers and to the
water supply industry.
b. The alternatives to coal tar base coatings, their cost,
availability, and acceptability for contact with potable
water.
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c. The composition of the coatings; and an identification of
substances that may be leached into the water from the
coatings.
d. Problems associated with application of the coatings in-
cluding application procedures, curing problems, and hazards
to workers who apply the coatings.
Information for this report was obtained from the open litera-
ture, industry trade associations, manufacturers, coating applicators,
municipal water engineers, U.S. government agencies, and engineering
consultants.
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2.0 COAL TAR BASED PRODUCTS
Coal tar is obtained by the destructive distillation of bitumi-
nous coal. In the United States, it is usually produced as a
by-product of the manufacture of metallurgical coke. The tar is
recovered from the coke oven gases by partial condensation. The
material escaping the initial partial condensation Is "light oil"
and gas. The tar can be further processed by fractional distilla-
tion to yield tar acids, tar bases, naphthalene, and creosote oil.
The residue remaining after distillation is commonly referred to as
pitch. It is dark brown to black in color and may range from a sticky
mass to a brittle solid. Most coal tar pitch made melts between 60°C
and 70°C (Bureau of Mines, 1968). The pitch fraction resists pene-
tration by water and resists deterioration by water action. These
characteristics make it highly desirable for such applications as
waterproofing and roofing, and for use in protective coatings for
burled or submerged Iron and steel structures and pipelines (Lowry,
1963). Approximately 1 million tons of pitch are sold annually in
the United States for all uses (Chemical Marketing Reporter. 1976).
The primary use of coal tar pitch, however, is as a binder in the
manufacture of carbon electrodes which are used in the electrolytic
production of aluminum.
2.1 Coal Tar Based Coatings Used In the Potable Water Supply Industry
Coal tar pitch Itself is generally not suitable as a protective
coating for metalwork. It softens when exposed to the sun in warm
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weather. At temperatures below freezing, it becomes brittle and may
crack or separate from the metal surface. Flowing water will produce
ripples in the coating, creating thin spots that reduce its protec-
tive capability (Bureau of Reclamation, 1976).
The American Water Works Association has specified minimum
requirements for the coal tar to be used in potable water systems.
These are that "coal tar shall be produced from coal that has a
minimum heating value of 13,000 Btu per pound on a moisture-and-
mineral-matter free basis (ASTM test method D-388) and that has
been carbonized in a slot-type coke oven at a temperature of not
less than 900°C.
Coal tar coatings suitable for use as a protective coating on
steel are made by combining coal tar pitch with other materials.
The coating retains the impervious properties of the pitch but the
undesirable properties of the straight pitch are overcome. There
are six coal tar based coating systems: 1. Hot Applied Coal Tar
Enamel; 2. Cold Applied Coal Tar Paint; 3. Cold Applied Tasteless
and Odorless Coal Tar Paint; 4. Coal Tar Epoxy Paint; 5. Coal Tar
Urethane Paint; and 6. Coal Tar Emulsion Paint. Within each of
these generic coal tar coating designations, numerous formulation
variations are possible. Some of these variations may be suitable
in a particular service for which other variations are not suitable.
Thus, for example, a manufacturer may sell a number of different coal
tar epoxy paints but only a few may be suitable for use in potable
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water. Each of the six generic coal tar coatings have been avail-
able in formulations considered suitable for potable water service
at one time* Some of them may no longer be sold. Koppers Company
(1978) stated that they did not know of any coal tar urethane cur-
rently for sale.
2.1.1 Hot Applied Coal Tar Enamel
The hot applied coal tar enamel used in water works systems
conforms to the C-203 specification of the American Water Works
Association (AWWA, 1964; 1973; 1978). The enamel is manufactured
by dispersing coal in a mixture of coal tar pitch or refined coal
tar and high boiling coal tar base oil at a temperature between 250°
and 350°C. The product can be adjusted to any desired softening
point/penetration specification by varying the proportions of the
three ingredients. The enamel is strengthened by the incorporation
of about 30 percent by weight of talc (Harris et al., 1975). The
enamel specified as a lining in steel water pipe is usually highly
plasticized and has the characteristics shown in Appendix B,
Table B-l (Bureau of Reclamation, 1976; Fair, 1956).
Hot applied coal tar enamel was first used in the United States
for lining steel water pipelines in 1914 by the City of New York
(Kinsey, 1973)* A water storage tank is reported to have been
enameled with coal tar in 1912 in southern California (Hayes, 1970).
Inspection of coal tar enameled pipes and tanks after many years of
service in water supply systems showed no coating failures when the
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material was properly applied (Hayes, 1940; Garrett, 1946). A
service life in excess of 50 years can be expected for the lining
(Bureau of Reclamation, 1976).
Coal tar enamel has a service life in excess of 50 years pri-
marily because of its resistance to absorption of water. Curves of
water absorbed by the coal tar enamel per square foot of surface
show almost no increase in water absorption beyond about 0.2 grams
of water absorbed per square foot after 20 days immersion (Fair,
1956). This characteristic of coal tar enamels is not changed by
addition of fillers to improve other properties of the enamel
(Hayes, 1940).
Other advantages of hot applied coal tar enamels are that they
have good erosion resistance and silt or small amounts of sand in
the water will not erode the lining. Algae and other growths do not
build up on coal tar enamel surfaces. The lining remains smooth and
therefore the carrying capacity of the pipe does not diminish over
time (Garrett, 1946).
Some disadvantages of the hot applied coal tar enamel are:
• The thickness of the lining (.094 inches) reduces the carry-
ing capacity of the pipe over what it would be if a thinner
liner were used. (The available cross-sectional area of a
20 inch pipe is reduced by 2 percent (Cook, 1977).)
• The enamel is easily damaged by welding heat which causes
the lining to char and peel off on each side of the weld.
This results in the dangerous and difficult job of repainting
the area with hot coal tar (Cook, 1977).
• In below freezing weather, great care must be taken in hand-
ling the pipe because of increased brittleness of the coating.
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• If an empty enamel lined pipe Is exposed to warm weather and
sunlight, it may shrink and harden. The enamel may then
develop cracks and the embrlttlement may be the cause of
later damage during the handling of the pipe (Bureau of
Reclamation, 1976).
• In storage tanks, where part of the enamel coated interior
may not be completely submerged, heat from the sun can cause
the enamel to sag and "alligator" (Hayes, 1940).
2.1.2 Cold Applied Coal Tar Paint
The cold applied coal tar paint is made of the same components
as the hot applied coal tar enamel but is liquified by the incorpora-
tion of coal tar solvents such as xylene or naphtha. It is easier to
apply than the hot applied coal tar enamel because it can be brushed
or sprayed on at ambient temperatures. The paint exhibits thixotropic
properties and can be applied in a thick film of approximately .020
inches without sagging or running (Fair, 1956).
The coating was recommended for use in water storage tanks above
the high water level by AWWA standard D 102-64 (AWWA, 1964). If used
underwater, it may contribute to taste and odor. It is also consi-
dered unsuitable for open top tanks, since sunlight will crack and
alligator the coating (Bureau of Reclamation, 1976; Fair, 1956). It
is also unsuitable for service temperatures above 71°C (dry) or above
38°C immersed, nor below -29°C (Fair, 1956). The coating is less
durable than the hot applied enamel and has a service life of between
5 and 10 years (Bureau of Reclamation, 1976). The Bureau of Recla-
mation no longer uses this paint system for new installations. They
have replaced it with a coal tar epoxy paint which is projected to
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have an immersion service life of at least 20 years (Bureau of
Reclamation, 1976). The proposed revision to the AWWA standard for
Painting Steel Water Storage Tanks does not include this coating
(AWWA, 1977).
2.1.3 Cold Applied Tasteless and Odorless Coal Tar Paint
The tasteless and odorless coal tar based paint suitable for use
in water storage tanks is composed of a selected pitch and coal tar
solvents which must be free of phenol or other materials which impart
taste or odor to the water. The paint contains no added filler, pig-
ments, fibrous materials, or asphalt material. It is applied in a
thin film having a dry film thickness of 0.002 inches per coat. AWWA
requirements for this paint are listed in Appendix B, Table B-2
(AWWA, 1964). A new cold applied coal tar paint system is specified
which is prepared by blending coal tar enamel with suitable solvents
to produce a taste- and odor-free paint. The coal tar enamel used
is similar to the hot applied coal tar enamel described above. The
dry film thickness of each coat is approximately 0.009 inches*
The AWWA standard (AWWA, 1964) states that the system will shrink
and crack if exposed to direct sunlight but gives good service when
kept shaded. It can be damaged by ice and therefore should not be
used where ice formation is anticipated.
2.1.4 Coal Tar Epoxy Paint
A coal tar epoxy paint suitable for use in the interior surfaces
of potable water storage tanks has been specified by the Steel
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Structures Painting Council (SSPC, 1973). This coating system is a
two-component paint which uses a co-reacting polyamide resin* and an
aromatic tertiary polyamine catalyst as curing agents. One component
of the paint contains a refined coal tar pitch, a liquid type polya-
mide resin, a polyamine catalyst, a mineral filler, a gelling agent,
and a volatile thinner. The catalyst accelerates curing of the paint
and the gelling agent Induces thixotropic antisag properties. The
second component of the paint system is a liquid type epoxy resin
which is mixed with the first component just prior to application.
The mixed paint contains approximately 75 percent by volume of non-
volatile film forming solids. Each coat will give a dry film thick-
ness of approximately 0.008 inches.
A typical composition of the coating system is shown in Appendix
B, Table B-3. Specifications for the ingredients of each component
and for the components are included in Appendix B, Tables B-4 through
B-8.
Coal tar epoxy paints using polyamines as the sole curing agent
are also available; however, one such coating which conforms to
Military Specification MIL-P-23236 (dated 28 June 1962) is reported
*The polyamide resin is a condensation product of a dimerized fatty
acid and a polyamine. Fatty acids derived from the following vege-
table oils have FDA approval for food contact surfaces: beechnut,
candlenut, castor, chinawood, coconut, corn, cottonseed, hempseed,
linseed, oiticica, perilla, poppyseed, pumpkinseed, safflower,
sesame, soybean, sunflower, tall oil, and walnut (CFR 21, Part
175.300, 1977). A number of polyamines acceptable for use on food
contact surfaces are also identified in the CFR. Among them are
tri(dimethylaminomethyl)phenol and ethylenediamine.
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to impart "highly objectionable taste and odor to water" for a period
of time (not specified) after curing (Bureau of Reclamation, 1976).
There are a variety of coal tar epoxy paints on the market which do
not conform to either the Military Specification or the Steel Struc-
tures Painting Council specifications which may or may not be suit-
able for use in potable water systems. A specification for a coal
tar epoxy paint system for the interior and exterior of steel water
pipe has been developed by the American Water Works Association
(AWWA, 1978). The specification was made available in April 1978.
It is not the same specification as that published by the Steel
Structures Painting Council (Kemp, 1978). The specification includes
a suggested formulation for a two package epoxy primer containing
non-toxic inhibitive ingredients (zinc phosphate or zinc molybdate
and micaceous iron oxide). Suggested ingredients for the coal tar
epoxy top coat are not given. However, characteristics of the coal
tar epoxy and performance requirements are given. A minimum curing
time of 7 days before placing the coated tank in service is specifled•
Coal tar epoxy resin paints cure as a hard film and the service
life in immersion service is anticipated to be in excess of 20 years.
A coal tar epoxy resin tested by Frye (1974) was not as abrasion
resistant as hot applied coal tar enamel. Coal tar epoxies chalk
when exposed to sunlight.
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2.1.5 Coal Tar Urethane Paints
Coal tar pitch can also be combined with polyurethane to make
a coating having properties similar to coal tar epoxy paints (Bureau
of Reclamation, 1976; SSPC, 1973). The polyurethanes are formed by
reaction between a diisocyanate and a polyhydroxy compound. The
properties of a polyurethane coating can vary widely depending on
the nature of the polyhydroxy compound used and also on the type of
isocyanate used. The coating can be formulated for fast or slow
drying, to give a hard, flexible, or soft film, and for ability to
resist chemical attack. Single component coatings can be prepared
that cure by oxidation or by reaction with atmospheric moisture. Two
component coatings can be prepared that use a catalyst to cure the
coating in a manner similar to the epoxy paints. The abrasion resis-
tance, hardness, and impact resistance of urethane are considered to
be outstanding. In a 25-year evaluation of water tank paints (Keane,
1975), a two-coat, 0.011 inch thick coal tar urethane was reported
to be giving good protection. It was rated as good as or better
than some vinyl and epoxy paints. However, in the same test, a
two-coat, 0.0045 inches thick coal tar urethane coating of the
same manufacturer showed total failure below the water line.
2.1.6 Coal Tar Emulsion Paint
Coal tar emulsion paint is formulated by suspending coal tar
pitch, inert mineral filler such as magnesium silicate, and rust
inhibitor such as zinc oxide in water instead of solvent. The
11
-------
advantages of coal tar emulsion paints over solvent based paints
are that they will adhere satisfactorily to damp surfaces and are
practically odorless (Bureau of Reclamation, 1976). They also show
better resistance to sunlight. The Bureau of Reclamation has found
that coal tar emulsions are not as watertight as the organic solvent
coal tar coatings. They are used by the Bureau to only a limited
extent for the protection of submerged metalwork (Bureau of Reclama-
tion, 1976).
Coal tar emulsion forms a strong bond with concrete and can be
used as a seal coat in cement mortar lined pipes. It acts as a
curing compound and forms a waterproof membrane which protects the
concrete from leaching. Koppers Company, however, states that it is
not suitable for water immersion service. Typical properties of coal
tar emulsion are presented in Appendix B, Table B-9. A typical coal
tar emulsion consists of 23.1 percent coal tar, 29.3 percent mineral
filler, and 47.6 percent water (Bricker, 1968).
2.2 Importance of Coal Tar Based Products to Producing Industry
There are two manufacturers of hot applied coal tar enamel for
pipe coating and for pipe and tank lining in the United States:
Koppers Company, and Reilly Tar and Chemical Company. Koppers Com-
pany also manufactures coal tar paints in addition to a number of
other types of paints used to line steel water tanks. There are
a number of other manufacturers and suppliers of coal tar paint
products. A partial list of these manufacturers is presented in
12
-------
Table 2-1. The coal tar paints of all these companies are not
necessarily used by the water supply industry.
Koppers Company reported sales of 6,000 tons, or approximately
$900,000 worth of hot applied coal tar enamel to the water supply
industry in 1976. In addition, 15,000 gallons of a chlorinated
rubber primer with a dollar value of $120,000 was used. Koppers
assumed that all of the hot applied coal tar enamel went to line
pipes and they assumed half of the steel pipes installed by the
water supply industry in 1976 were lined with the material.
Sales of coal tar enamel to the water supply industry for tank
linings represents about 10 percent ($600,000) of the business of
Reilly Tar and Chemical Company. Their customers are primarily in
the Southwest and Midwest.
Koppers Company estimates that they supply 80 percent of the
coal tar paints to the water supply industry and that the value of
these paints was approximately $450,000 in 1976. Approximately half
of the market for coal tar paints is believed to be for relining
existing tanks.
13
-------
TABLE 2-1
PARTIAL LIST OF MANUFACTURERS OF COAL TAR BASED PAINTS
American Tar Company
1702 N. Northlake Way
Seattle, Washington
Randolph Products Company
Park Place East
Carlstadt, New Jersey
Briggs Bituminous Composition
Company
2745 North Amber Street
Philadelphia, Pennsylvania
Calbar, Inc.
2620 N. Martha Street
Philadelphia, Pennsylvania
Riley Brothers, Inc.
858 Washington
Burlington, Iowa
Samuel Cabot, Inc.
Dept. 1371
1 Union Street
Boston, Massachusetts
Everseal Manufacturing Company,
Inc.
477 Broad Avenue
Ridgefield, New Jersey
Sterling Division of Reichold
Chemicals, Inc.
1977 Ohio River Blvd.
Sewickley, Pennsylvania
Glidden Coatings & Resins
Architectural and Maintenance
Division of SCM Corporation
Cleveland, Ohio
Tnemec Company, Inc.
121 W. 23rd Avenue
P.O. Box 1749
Kansas City, Missouri
Koppers Company, Inc.
1900 Koppers Building
Pittsburgh, Pennsylvania
Tropical Paint Company
2630 Pearl Road
Medina, Ohio
Mass and Waldstein Company
2121-T MeCarter Highway
Neward, New Jersey
Matcote Company, Inc.
P.O. Box 10762-TR
Houston, Texas
Universal Protective
Coatings
123-29 Jordan Street
San Rafael, California
14
-------
3.0 ALTERNATIVES TO THE USE OF COAL TAR BASED LININGS IN POTABLE
WATER DISTRIBUTION SYSTEMS
Alternatives to the use of coal tar based linings in potable
water distribution systems include:
• the use of non-coal tar based linings;
• the use of cathodic protection;
• water conditioning, and
• the use of noncorroding construction materials.
Non-coal tar based linings - A number of non-coal tar based lining
materials are currently being used by the water supply industry for
iron and steel water pipelines and storage tanks. The two most
commonly used non-coal tar based lining materials for steel water
pipelines are cement mortar and epoxy. Cement mortar is applied as
a 0.30 to 0.50 inch thick lining. Liberation of calcium hydroxide
from the cement mortar inhibits rusting. Cement mortar was first
used in steel water pipes in the late 1800s and some of those early
pipelines were in service for the better part of a century. Cement
mortar lining of steel pipes is practiced in accordance with AWWA
standard C205-71 (AWWA, 1971). Among the advantages of cement mortar
linings over organic lining materials (Padley, 1975) are:
• lower cost;
• lower sensitivity to variations in substrate quality;
• lower sensitivity to variations in application procedures;
15
-------
• provides protection to uncoated metal at pipe Joints;
• fewer coating imperfections ("holidays");
• reduced sensitivity to "holidays";
• form a pipe within a pipe which is securly held in place by a
"keystone" effect even if cracked or damaged in handling;
and
• surface fissures in the lining "self heal" when immersed in
water (Padley, 1975; Wagner, 1974).
A disadvantage of a cement mortar lining in steel pipe is that
it can fail by cracking and breaking loose in pipes subject to
excessive deflection. The acceptable deflection of cement mortar
lined pipe is less than that for coal tar enamel lined pipe (AISI,
1977) and for epoxy lined pipe (Cook, 1977). Another disadvantage
of cement mortar linings is that the thickness of the lining reduces
the available cross-sectional area and water carrying capacity of the
pipe more than either coal tar enamel or epoxy. The cross-sectional
area of a 20-inch inside diameter pipe lined with cement mortar is
reduced by over 6 percent. A coal tar lining reduces the cross-
sectional area by 2 percent and an epoxy lining reduces the cross-
sectional area by less than 0.2 percent.
At the present time, cement mortar is the only material used
to line cast iron and ductile Iron pipe (Higgins, 1977; Dahl, 1977).
American National Standard A21.4-1974 (ANSI, 1974) covers cement
mortar linings for cast iron and ductile iron pipe and fittings for
16
-------
water. The ANSI standard suggests the use of a bituminous seal coat
over the cement mortar lining in cast iron and ductile iron pipe.
The purposes of the seal coat are to aid the cement curing process by
retaining moisture, and to protect the cement mortar from decalcifi-
cation In soft (calcium dissolving) waters. The seal coat is most
commonly, a petroleum derived asphalt based coating. The coating is
about 0.001 inch thick.
The AWWA standard for cement mortar lining of steel pipes does
not include the use of a seal coat as a curing aid (AWWA, 1971).
In April 1978, the AWWA published a standard for lining steel
waterpipe with coal tar epoxy. Non-coal tar based epoxy systems that
have been used to line water pipes include an epoxy phenolic formula-
tion (Frye, 1974) and polyamide cured epoxy formulations (Crawshaw,
1974; Kipin, 1978; Lingle, 1978). The epoxy paints can be formulated
with components that have FDA approval for food contact surfaces.
The AWWA standard for painting and repainting steel tanks for
water storage (AWWA, 1964) includes several types of non-coal tar
based paint systems. These are:
• Red Lead Aluminum Phenolic
• Vinyl
• Zinc Phenolic
• High Solids Vinyl
• Hot Applied Wax
• Cold Applied Wax
17
-------
• Metallic Zinc
Since the original standard was published, new paint systems
have been developed and have come into use while other systems have
practically gone out of use. The AWWA standard is currently being
revised to include some of the newer paints and to eliminate some of
the lesser used paints. The latest draft of the revision omits red
lead, aluminum phenolic, zinc phenolic, hot applied wax, and cold
applied wax (AWWA, 1977). It adds a two-component epoxy paint system
and a chlorinated rubber paint system.
Omission of a paint system from the standard does not imply that
it cannot be used, only that the newer systems appear more useful.
The draft revised standard includes a reference to the original
standard for cold applied wax and for hot applied wax and reprints it
as a "convenience" for those who may still wish to use that lining.
The standard also states that "the ideal arrangement is for purchasers
to cooperate with reputable paint manufacturers who will agree to
furnish paint systems which have proved to perform as well as or
better than those included in this standard." There are numerous
paint systems on the market which have been approved for use in
potable water storage tanks by local, state, and federal government
agencies. While many of these conform to the AWWA standard, many
others are variations of the AWWA standard systems or completely
different proprietary paint systems. One of the reasons for revising
the AWWA standard was to recognize that new paint systems have been
18
-------
developed and that they are currently being used with satisfactory
results.
A brief description of some of the non-coal tar based linings
that have been used in potable water systems is included in Appendix
A. Table 3-1 presents a comparison of several paint systems used to
line water tanks and pipelines•
Cathodic Protection - Corrosion is an electrochemical phenomenon.
When two dissimilar metals are metallically connected in an electro-
lyte, a current flows in the electrolyte from the corroding metal
(the anode) to the more "noble" metal (the cathode) which does not
corrode. Cathodic protection is a means of making the corroding
metal a cathode. Two methods of providing cathodic protection are
in use. These are the sacrificial anode method and the impressed
voltage method. The sacrificial anode method involves using less
"noble" metals as anodes in electrical contact with the metal to be
protected. The less "noble" metal then corrodes instead. Zinc,
magnesium, or aluminum are usually used as the sacrificial anode.
Note that if this procedure is used to protect the interior of water
tanks, corrosion products of the sacrificial anode could enter the
water. In the impressed voltage method, an electric current is pro-
vided by an external source and Is passed through the system by use
of a non-corroding anode, such as carbon or platinum, which is sus-
pended in the water.
Cathodic protection is frequently used in conjunction with a
protective coating to control corrosion. The coating acts as an
19
-------
Table 3-1
COMPARISON OF ALTERNATIVE HATER SYSTEM LININGS WITH RESPECT
TO SELECTED VARIABLES AFFECTING THEIR USE
ro
o
Coating use
Coal Tar
hot applied enamel Tanks & Pipes
cold applied paint Tanks
Coal Tar Epoiy Tanks S Pipes
Vinyl Tanks
Epoiy Tanks 4 Pipes
Chlorinated Rubber Tanks
Metallised Zinc Tanks
Uax
cold applied Tanks
hot applied Tanks
Phenolic Tanks
Zinc-rich Tanks
Asphalt Tanks
Cement-mortar Pipes
Surface Number Total mil
Preparation of Coats Thickness
Commercial blast
2-3 62-124
2-3 16-20
Near-white blast 2 16
Near-white blast 3-5 4.5-6.0
Near-white blast 2-3 8.0-15
Sear-white blast 3 6.0-9.5
White metal blast 1 7.5-10.0
Removal of loose 1 20-30
particles only 1 30-60
Commercial blast 3 3-5
Near-white blast 1 2-5
Commercial blast 3 15
Removal of loose 1 250-500
or foreign Batter
Curing Environmental Restrictions
Tine during application & drvlna. Comments
5-10 days >10°C
5-10 days r-4°C
5-10 days >10°C
depending on
teaperature
2 days with 2-32'C
heated air <80Z R.H.
5-14 days S
21* C «
7-10 days 9 >10"C
16"C <80Z R.H.
temperature
must be greater
than 16"C for
curing
7 days tbt critical
none •> re-
strictions
24 hours >J,°C
24 hours unless heated
7 days >4°C
7 days >2°C
R.H. 50-851
7 days >4'C
7 days above freez-
ing
'
\
1) shortage of qualified applicators
2) hot applied-predominantly west coast
use
3) skin and eye irritant
1) short pot life
2) shortage of refined pitch
3) solvents which must be used don't
comply with Rule 66, California
Pollution Laws
4) may contribute to taste & odor
problems
1) at least 24 hours drying between
coats for solvent releaae is
recommended
1) Ameron recommends baking at 60° C
for 24-48 hours for proper curing
2) at least 24 hours drying time
between coats but not longer than
one week
3) skin irritant
1) not widely used for water storage
tanks
1) metal must be applied Immediately
after blasting
2) toxic fumes produced
1) wax coatings are predominantly used
to recoat old tanks
2) tanks are usually only out of
service 2-5 days (100,00 gal tank)
1) intercoat adhesion problems
1) used predominantly as primer
1) major use is for recoat ing
(maintenance)
1) Limits allowable pipe deflection
2) Has self-healing characteristics for
small cracks
3) Seal coat is used over mortar in
cast iron pipe
4) Subject to decalciflcatlon In soft
water if seal coat not used
-------
insulator and minimizes the current requirements of cathodic protec-
tion. The cathodic protection system protects areas which may have
lost the protection of the coating due to coating discontinuity or
coating failure. Cathodic protection has been used to protect the
interior of water tanks and the exterior of buried water pipes. It
cannot be used to protect the interior of pipelines (Koppers, 1978).
Water Conditioning - Water treatment and conditioning can also be
used to control corrosion. The presence of oxygen is required for
corrosion of iron and steel to take place. If oxygen can be removed
from the water, corrosion will not occur. However, removal of oxygen
from the large volumes of water involved in potable water supply
systems is usually not practical. Calcium carbonate films formed by
precipitation of calcium carbonate onto the metal surface will also
retard corrosion (Merrill and Sands, 1978).
Non-corroding construction materials - Water pipelines and storage
tanks can also be constructed of materials that are less susceptible
to corrosion than iron and steel. Pipes and tanks can be fabricated
from polyvinyl chloride, fiberglass-reinforced plastic, asbestos
cement, stainless steel, concrete, copper, wood, polyethylene, and
other materials. Limitations on the use of these alternatives
include cost and ability to withstand environmental stresses. Iron
and steel are generally the cheapest metals available. They are
also strong and capable of withstanding the environmental stresses
to which water pipes and storage tanks may be subject. These include,
21
-------
for example, wind, earthquake, and, In the case of burled pipe, the
effect of heavy traffic and the pressures developed underground
during winter freeze-thaw cycles.
In terms of miles of pipe in place in the U.S., cast iron is
the leading type of water pipe. It accounted for more than 75
percent of water pipe mileage in place in 1975. It also accounted
for 45.8 percent of the water pipe mileage Installed in 1975.
Asbestos cement pipe and steel pipe account for 13.1 and 5.9 percent,
respectively, of water pipe in place in 1975. The use of steel pipe
for new installations showed a decline in 1975 when it accounted for
only 3.4 percent of water pipe mileage installed. A summary of pipes
installed in 1975 and pipe in place in 1975 by type and size of pipe
is presented in Table 3-2.
Water storage tanks have been constructed of wood, fiberglass
and concrete. Concrete has been widely used for the construction of
large capacity tanks. It is estimated that almost 15 percent of new
water tanks are constructed of concrete. Concrete is considered
economical for tanks with capacities between 1.25 and 5 million
gallons. Below that, steel is more economical (Meek, 1978). Steel
is also more adaptable for elevated use (Koppers, 1978). A concrete
tank has lower maintenance costs than a steel tank because It does
not require a protective coating (Dickson, 1978). In the Northwest
region of the country, leakage problems have been encountered with
concrete tanks and their use has been discontinued in that area
(Baker, 1978).
22
-------
TABLE 3-2
PIPE USED IN U.S. WATER SUPPLY DISTRIBUTION SYSTEMS BY
UTILITIES SERVING OVER 2,500 PERSONS
TYPE OF PIPE
Cast Iron
Asbestos Cement
Steel
Reinforced Concrete
Plastic
Ductile Iron
Galvanized Wrought Iron
Wood
RCP Steel Cylinder
Black Galvanized Iron
Copper
All others and unidentified
MILEAGE
IN PLACE
(beginning
of 1975)
481,816
83,871
37,852
10,083
6,981
7,498
2,364
1,246
652
431
312
6,879
Z OF
TOTAL
75.29
13.11
5.91
1.58
1.09
1.17
0.37
0.19
0.10
0.07
0.05
1.07
MILEAGE
INSTALLED
(1975)
6,847
3,743
505
517
1,826
1,388
3
*
8
*
*
96
PERCENT OF
Under 6"
15.7
9.7
53.4
0.2
62.0
*
*
*
*
*
*
PIPE MILEAGE IN PLACE AX BEGINNING OF
1975 BY DIAMETER
6"-12" 13"-24" Over 24"
76.7 6.6 1.0
86.3 4.0 0.1
29.5 10.7 6.4
4.1 43.4 52.3
37.3 0.6 0.1
* * *
* * *
* * *
* * *
* * *
* * *
Source: Scott and Caesar, 1975
*Not Specified
-------
Approximately 100 redwood tanks are used by the California Water
Service. A typical tank has a capacity of 25,000 to 50,000 gallons,
the largest being 250,000 gallons• Because of their limited capacity,
wood tanks are no longer being constructed for the California Water
Service. The Service is attempting to salvage some leaky tanks by
lining them with fiberglass-reinforced plastic. The wood is used as
a frame for construction. The result is a fiberglass-reinforced
plastic tank supported by the wood.
Some fiberglass-reinforced plastic tanks are in use for potable
water storage but they are not common (Meadows, 1978). Cost and
quality control problems with onsite fabrication of large fiberglass-
reinforced plastic tanks generally limit the capacity of the tanks to
that which can be shop fabricated and transported (Reinhart, 1975).
Fiberglass tanks of up to 48,000 gallon capacity have been shop
constructed (Kraft, 1978).
Comparative cost information for tanks of concrete, fiberglass-
reinforced plastic, wood and steel is presented in Table 3-3.
3.1 Water Supply Industry Preferences for Protective Linings in the
Water Distribution System
The selection of materials to be used in a water distribution
system is influenced by many factors. The foremost consideration in
the selection of material that will be in contact with potable water
is its potential to introduce toxic substances or taste and odor into
the water. For information on the acceptability of materials in this
regard, water supply utilities and contractors rely on the advice of
24
-------
TABLE 3-3
COMPARISON OF THE COST OF CONSTRUCTION OF WATER TANKS BY CONSTRUCTION MATERIAL
TANK CAPACITY
(gallons)
3,000
10,000
20,000
30,000
45,000
50,000
100,000
250,000
500,000
1,000,000
2,000,000
4,000,000
6,000,000
8,000,000
10,000,000
CONSTRUCTION MATERIAL
WOOD
GROUND
LEVEL
3,780
8,140
10,485
13,185
16,615
—
—
—
—
—
—
—
—
—
^™
FIBERGLASS-
REINFORCED
PLASTIC
GROUND
LEVEL
—
—
—
—
22,500
—
—
—
—
—
—
—
—
—
~~
CONCRETE
GROUND
LEVEL
—
—
—
—
—
—
—
92,000
132,000
212,000
333,500
546,000
760,000
—
—
GROUND
LEVEL
—
—
—
—
—
—
35,000
52,000
77,500
145,000
240,000
420,000
600,000
760, 000
900,000
STEEL
STANDPIPE
—
—
—
—
—
—
—
125,000
192,500
325,000
—
—
—
—
ELEVATED
—
—
—
—
105,000
130,000
195,000
280,000
490,000
—
—
—
—
—
to
Ul
Sources: Means, 1975 for all except fiberglass reinforced plastic tanks.
Kraft, 1978 for fiberglass reinforced plastic tanks.
*— means cost data not available from above sources.
-------
state and local health departments, and various U.S. government
agencies, including the U.S. Public Health Service, the Food and Drug
Administration and the U.S. Environmental Protection Agency. Accept-
ability is based on a determination that the coatings contain no
toxic ingredients and on the results of an extraction test. The
extraction test measures the weight of extractables in a water sample
exposed to the cured coating (see Appendix E).
The other Important factors influencing selection are the dura-
bility and cost of the material. In choosing from among several
acceptable alternatives, the experience and preferences of the con-
tractor or public works engineer regarding the various alternatives
will influence the choice.
Until recently, the most widely used lining materials for steel
water pipe were hot applied coal tar enamel and cement mortar. Epoxy
linings are now beginning to be used. Three pipeline companies
indicated that they only use epoxy to line steel pipe (Kipin, 1978;
Lingle, 1978; Husselbaugh, 1978). The AWWA has Issued a standard for
coal tar epoxy lining for steel water pipe (AWWA, 1978). One of the
reasons given for switching from coal tar enamel is the difficulty of
controlling fumes released during application of the enamel (Lingle,
1978; Kipin, 1978; Husselbaugh, 1978; Roschburg, 1978). One pipe
lining company indicated that they use coal tar enamel for 60 percent
of their pipe lining jobs and epoxy for another 25 percent of their
Jobs. .It was stated that coal tar is 75 to 80 percent cheaper than
26
-------
cpoxy on large jobs. Hovever, water supply Industry pipe lining jobs
could not be separated from other pipe lining jobs (Crane, 1978).
Over 1,000 steel water storage tanks are constructed each year
(Harper, 1977; Hauser, 1977; Lawrence, 1977; Arnell, 1977). Many
different linings have been used. Some localities prefer coal tar
enamel. In Seattle, nearly 100 percent of the steel water tanks are
lined with coal tar enamel. In 1977, in Seattle, 14 of 15 new water
tanks were lined with coal tar enamel (Garrison, 1978). In Los
Angeles, coal tar enamel is used above the low water mark (Lemans,
1978). Coal tar enamel is used to line water tanks in Atlanta;
however, if relining is required, vinyl is used (Layton, 1978).
Vinyls and epoxies are used in Houston, exclusively (Healer, 1978).
Virginia has withdrawn coatings that contain lead, coal tar, vinyl,
tarytes, lampblack, carbon black, or bituminous material from their
list of approved water tank linings (Bartsch, 1977). In Baltimore
County, hot applied coal tar enamel was used to line steel water
tanks in the past. However, new specifications call for a chlor-
inated rubber type paint. The major reason for abandoning coal tar
is the difficulty of controlling fumes (Silham, 1977). The Cali-
fornia Water Service has 175 coal tar enamel lined tanks in service.
They recently stopped using coal tar enamel in new tanks because of
reports that it may Introduce toxic substances to the water. A new
27
-------
proprietary bituminous coating system that is advertised as FDA
certified* for contact with potable water is being tried (Steiber,
1978).
California has had poor experience with vinyl paints. It was
reported that a high solids vinyl failed in less than a year in a
California water tank (Dickson, 1978). Steiber (1978) stated that
vinyl does not hold up well in soft water. Formulation changes
required to meet California air pollution control regulations are
also believed to adversely affect the performance of vinyl paints
(Boyd, 1978). Epoxy paints are also adversely affected for the same
reason.
There are no statistical data on the number of tanks lined with
particular paints. Estimates of the extent of use of different paint
systems nationwide were solicited from tank fabricators, coatings
suppliers and engineers. The estimates are tabulated in Table 3-4.
It can be seen that the estimates are conflicting. The reason for
the conflicting responses is believed to be that the estimates
reflect the personal experiences of the estimator and may also be
influenced by personal preferences or interests. An engineering
consultant estimates that his company specifies high solids vinyl
for 90 percent of its projects and epoxy linings for the remaining
10 percent (Brotsky, 1977). Two of the larger water tank maintenance
companies in the United States (Pittsburgh Tank and Tower Company and
Leary Construction Company) estimate that 70 to 80 percent of all
*The FDA states that they do not certify coatings for use in potable
water. 28
-------
Table 3-4
TABULATION OF VARIOUS ESTIMATES OF THE PERCENTAGE OF NEW WATER TANKS
LINED WITH A GIVEN PAINT SYSTEM NATIONWIDE
Paint System
Is}
Vinyl
Epoxy
Coal Tar
Other
Garrett
1977
80-90
10-20
0
-
Wallace
1977
90
6
0
4
Enoch
1977
47.5
47.5
5
0
Songer
1977
75
15
0
10
McCoy
1977
*
50*
*
-
Fisher
Tank
90
9
1
Van Sant Dickson Campbell
1978 1978 1978
90 - -
10
0 90 0
0 - -
Carvlin
1978
SO
l'»
13
17**
*Estimated as 50 percent vinyl and coal tar and 50 percent epoxy.
** Includes 8Z asphalt
-------
water tanks in the country are lined with wax. They currently coat
about 700 to 800 tanks per year, but most of this is recoating of
older tanks. Jackson (1970) states that wax coating has practically
gone out of use.
3.2 Comparison of the Cost of Alternative Protective Linings
Many factors enter into the decision of choosing a particular
protective lining for water tanks and pipelines. Among the important
factors is the cost of the lining. In water distribution systems it
is desirable to minimize maintenance requirements that would entail
an interruption to service. Thus, the benefits of a durable lining
may outweigh initial cost differences between linings. A better cost
comparison is one based on the life cycle cost.
The cost of lining a pipe or a tank depends on many factors,
including weather, season of the year, union restrictions, environ-
mental regulations, the availability and cost of manpower and
supplies, degree of surface preparation, methods of application,
the type of painting system, and other factors. Many of these
factors are job-specific and therefore cannot be considered in a
general comparison of the costs. In order to present a reasonable
cost comparison between linings for purposes of this paper, estimates
were obtained from the published literature and from paint suppliers,
engineering consultants, and painting contractors (Table 3-5). In
addition, costs were calculated for selected linings using Means Cost
Data, 1975 (Means, 1975) and the Estimating Guide of the Painting and
30
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TABLE 3-5
ESTIMATES OF THE COST OF APPLYING SELECTED LINIHGS TO POTABLE HATER TANKS BY SOURCE
Coating
3-coat vinyl
4-coat vinyl
1-cosjponent epoxy
2-component epoxy
Coal tar epoxy
Coal Tar
cold applied
hot applied
Chlorinated lubber
Metallized Zinc
sax
Zinc-rich
Phenolic
Asphalt
Inertol f49
Thick*
Petropoxy
Source
Brotsky, 1977
Kopperi
Means
Sterling Chemical
AHHA, 1970
Koppers
Means
Sterling Chemical
AHHA, 1970
Koppers
Means
Sterling Chemical
AHHA. 1970
Brotsky
Koppers
Means
Sterling Chemical
Brotsky
Koppers
Means
Koppers
Hsans
Robison-Burnap
D. E. Burgess Co.
SKILL Fainting
Robison-Burnap
Brotsky
Koppers
Means
Barges. 1978
Harner •- '
Pittsburgh Tank Co.
Kessler Tank Co.
Brotsky
Means
Brotsky
Koppers
Means
Koppers
Means
Koppers
Means
Surface
Preparation
S/Sq ft
1.00
0.50
1.00
0.47
O.SO
1.00
0.47
0.24
O.SO
0.75
0.47
0.24
0.30
0.50
0.75
0.47
0.30
0.30
0.75
0.30
0.75
0.40
0.40
0.30
0.50
a 75
0.30
1.65
0.12
1.00
1.00
0.30
0.50
0.75
0.30
0.75
0.50
1.00
Materials
S/S<, ft
0.22
0.11
0.15
0.15
0.18
0.09
0.15
0.25
0.08
0.06
0.15
0.15
0.50
0.18
0.15
0.15
0.13
0.25
0.15
0.10
0.14
0.05
0.50
0.04
0.25
0.13
0.11
0.10
a 24
Initial
Application Cost
S/Sq ft S/Sq ft
0.50
0.16
0.33
0.50
0.21
0.43
0.22
0.50
0.50
0.31
0.17
0.50
0.70
0.25
0.30
0.25
0.30
0.30
0.60
0.60
0.50
0.16
0.15
1.75
0.29
0.15
0.50
0.30
0.30
0.50
0.30
1.11
0.95
1.15
1.08
0.55
1.15
1.50
0.86
0.47
1.15
1.95
0.9O
0.75
0.73
1.30
0.85-1.25
1.15
• 1.10
1.50-2.00
1.14
a so
3.90
a 35
0.45
1.40
1.11
070
1.24
Service
Life
Years
8
8
8
10
10
10
10
15
10
12
15
20
6
40-50
4
5
6
6
15
Cost Effectiveness
$/Sq ft /year
0.139
0.119
0.144
0.108
0.115
0.086
0.115
0.060
0.075
0.061
0.055-0.
0.075-0.
a 190
0.098-0.
0.088
a 090
a 185
a 117
0.083
083
100
. ,m
078
-------
u>
Table 3-6
MITRE COST ESTIMATES
FOR APPLYING SELECTED LININGS TO POTABLE WATER TANKS
Coating
Coal Tar Enamel (hot)
3-coat vinyl
Metallized Zinc
4-coat vinyl
Chlorinated Rubber
Coal Tar paint (cold applied)
Coal Tar Epozy
2-compouent epozy
Asphalt
PetropoxyR
Haz
1-component epozy
Asphalt
Inertol *49 ThickR
Phenolic
Zinc-rich
Surface
Preparation
S/Sq ft
0.50
0.80
0.80
0.80
0.50
0.50
0.50
0.80
0.80
Materials
$/Sq ft *
0.14(Lingle)
0.15
O.SO(Warner)
0.20
0.17
0.13
0.20
0.15
0.24
0 . 12 (Schetzer) . 04(Shet zer)
0.80
0.50
0.50
0.80
0.12
0.11
0.11
0.25 (Means)
Application Initial Cost
$/sq ft $/sq ft
0.30
0.16
1.15
0.21
0.16
0.30
0.25
0.16
0.30
0.29 (Schetzer)
0.16
0.30
0.16
0.05
0.94
1.11
2.45
1.21
0.83
0.93
0-95
1.11
1.34
0.45
1.08
0,91
0.77
1.10
Service
Life
Years **
50
23
50
23
15
15
14
14
15
5
10
6
4
5
Cost Effectiveness Relative
$ Sq ft/year Costs
0.019
0.048
0.049
0.053
0.055
0.062
0.068
0.079
0.089
0.090
Q.108
0.152
0.193
0.220
1.00
2.53
2.58
2.79
2.89
3.26
3.58
4.16
4.68
4.74
5.68
8.00
10.16
11.58
*Costs froB Coppers unless otherwise indicated
** Service Life la an average of estimates obtained from vendors and users by phone.
-------
Decorating Contractors of America (PDCA, 1977). These are tabulated
in Table 3-6. In addition to the total cost, the tables include the
three main cost components: surface preparation, materials, and
application cost. An annualized cost based on the estimated service
life of the lining is also presented. Table 3-6 includes a relative
cost figure which is the ratio of the annualized cost of the lining
and the annualized cost of a coal tar enamel lining.
The cost-effectiveness of a lining and thus its relative cost,
is sensitive to its service life. For example, if a 3-coat vinyl
lining lasts only 8 years instead of 23 years, its cost-effectiveness
and relative cost would approximately triple. Unfortunately, the
reported service life for each lining varies widely. A poor service
life may have been experienced because of faulty application proce-
dures rather than because of the inherent properties of the lining.
Thus, the cost-effectiveness and the relative cost figures indicated
in the table may not reflect achievable costs.
The most significant component of the initial cost of most
linings is the cost of surface preparation* However, since surface
preparation has a major influence on the service life of a lining,
it is generally not advisable to try to "cut corners" in this
area of the Job.
There is also uncertainty regarding the cost of applying hot
coal tar enamel. There is disagreement concerning the degree of
skill required to apply the hot coal tar enamel. Some references
33
-------
point out the Importance of using experienced applicators (SSPC,
1973; Bureau of Reclamation, 1976). According to the SSPC, some
consulting engineers demand that a contractor submit at least 10
5-year case histories in order to qualify. Other reports (Wood,
1975; Steiber, 1978) state that coal tar enamel is tolerant to
poor surface preparation and to mistakes in application* It is
reported that the number of experienced applicators is dwindling,
particularly in the east, and that those who are willing to apply the
coal tar demand upwards of $2.00 per square foot (Campbell, 1978).
However, as can be seen in Tables 3-5 and 3-6, most cost estimates
were about half that amount.
The choice of pipe material for water main construction is
based upon technical considerations at the particular installa-
tion (soil conditions, potential for future connections, location),
material availability, and cost, tempered by the personal prefer-
ences of the utility or contractor (Imhoffer, 1973). With regard
to cost, asbestos cement pipe in sizes up to 3 Inches is about half
the cost of cement lined cast iron pipe (Means, 1975). Unlined
steel pipe in sizes up to 8 inches is between 1-1/2 and 2-1/2 times
the cost of cement mortar lined cast iron pipe (Means, 1975). Steel
pipe is commonly lined with cement mortar, hot applied coal tar
enamel or epoxy. Materials cost for enamel and cement mortar are
approximately 14 cents and 34 cents per square foot, respectively
(Lingle, 1978; Lawrence, 1977). However, surface preparation
34
-------
requirements for application of the coal tar enamel are greater and
more costly and tend to equalize the total cost for lining with that
of cement mortar. The cost of lining steel pipes with epoxy was
estimated at 60 cents per square foot (Kipin, 1978).
35
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4.0 UTILIZATION OF COATING MATERIALS
In this section the methods for application of the various coat-
Ing materials are delineated followed by a brief discussion of the
expected and Identified problems associated with application.
4.1 Application Methods
The performance of a protective coating depends in large part
on surface preparation and on careful and proper application of the
coating. Specification of the requirements necessary for a complete
paint job have been published by the Steel Structures Painting
Council (1973), the American Water Works Association (AWWA, 1972;
AWWA, 1964), and by the coating manufacturers* It has been shown
that a near-white blast cleaning or white metal blast cleaning Is the
minimum level of surface preparation required for long-term perform-
ance (Berger, 1976). The draft AWWA standard for painting and
repainting steel tanks (AWWA, 1977) specifies a near white blast
cleaning or pickling of the tank surface before application of most
coating systems. Pickling removes all mill scale, rust and rust
scale from the metal surface. Blast cleaning removes nearly all mill
scale rust, and rust scale, and can also remove paint and other
foreign matter. White metal blast cleaning is essentially equivalent
to pickling in the degree to which the metal surface is cleaned. A
near-white blast cleaned surface is 95 percent free of all visible
discoloration. A commercial blast cleaned surface is two-thirds free
of all visible discoloration.
36
-------
The first coat of paint should be applied as soon as possible
after cleaning to prevent rust formation. If rust is allowed to form
before the paint is applied, it is necessary to clean the metal
again.
Protection of the steel surface depends on good bonding of the
paint to the steel and to prior coats, and on film thickness. Proper
curing procedures also must be followed. If a coating dries too
slowly, excessive dust and dirt may accumulate on the coating. There
may be a maximum time interval between application of successive
coats to assure good intercoat adhesion. Poor ventilation can retard
curing of the coating by slowing evaporation of the solvent. Since
solvent fumes are heavier than air they will collect at the bottom of
the tank unless steps are taken to remove them.
Pipe linings can be applied in the shop or the field. Storage
tanks, because of their large size, are usually erected in the field
and lined in place.
Hot coal tar enamel and cement mortar linings are usually shop
applied to pipes by a centrifugal lining process.. The process
involves feeding the lining material into the bore of a rotating pipe
so that the lining material is spread uniformly over the pipe bore by
centrifugal force. Fittings are lined by manual methods.
Coal tar enamel linings can be damaged at joints if pipe sections
are connected by welding. In pipes larger than about 27 Inches in
37
-------
diameter, the joints can be manually lined In the field, otherwise
mechanical joining methods are used.
Cement mortar can also be applied to pipe interiors by a spray
process. In this process, a centrifugal applicator head, situated at
the end of a lance that is supported on a wheeled carriage, is pushed
through the pipe. The mortar mix is pumped through the lance to the
applicator head which throws the mix onto the pipe surface.
Epoxy linings are usually field applied after the pipe is in
place and all welding is complete. The lining can be applied by
forcing the epoxy mixture through calibrated orifice openings in
pigs in the correct quantity against the pipewall as the pig is
propelled through the pipe by compressed air. If the lining is shop
applied, mechanical pipe joining methods are used.
Hot applied coal tar is applied to storage tanks by a hand
daubing procedure. Other linings are usually spray applied to a
specified film thickness in one or more coats.
A summary of the application procedures for several pipe and
tank linings are included in Appendix D. The manufacturers recommend-
ations should be followed with regard to the time to allow for curing
of the paint before placing the tank or pipe in service.
Following application and curing of the lining, the water tank
or pipeline is disinfected before It is placed in service. Some
state and local health departments have developed their own proce-
dures. The AWWA has described two acceptable methods for disinfecting
water tanks in their standard for painting water tanks (AWWA, 1964).
38
-------
The first AWWA method calls for filling the tank slowly to the
overflow level with potable water to which enough chlorine has been
added to produce a concentration of 50 ppm in the full tank. Filling
the tank will provide a thorough mix of the chlorine and water to
assure contact with all surfaces for disinfection. After the tank
has been filled it must stand full for about 6 hours, preferably 24
hours. After this holding period, the tank is drained and then
refilled using the regular water supply. Water samples must be taken
to determine the effectiveness of the disinfection process.
Use of the second method is less desirable (Trichilo, 1979). It
calls for placing water containing 50 ppm chlorine in the tank to a
level which will enable a concentration of 2 ppm to be attained when
a sufficient amount of regular water is added to fill the tank. The
water containing 50 ppm of chlorine is held in the tank for 24 hours
before the tank is filled with the regular water supply. The full
tank is then allowed to stand for 24 hours. After this time, the
tank may be put into service without draining the water used to
disinfect it.
4.2 Problems Associated with the Application of Coatings
The problems associated with the application of coatings in-
clude:
• potential toxic effects of the paint on the applicator;
• requirements for control of emissions to the atmosphere;
• requirements for ventilation during application and curing;
39
-------
• insuring adequate curing time before placing in service;
• safety in rigging; and
• visibility in the closed tank.
The latter two problems are common to the application of all
coatings Inside water storage tanks. The other problems vary accord-
ing to the coating system used.
Ventilation is the key to safety for most paint systems since
toxic and flammable solvents are components of most paint systems
usedt Sufficient ventilation must be provided to keep the solvent
concentration in all parts of the tank below the lower explosive
limit during the entire application and curing period. Since the
solvent vapors may be heavier than air and settle to lower parts of
the tank, they should be removed by suction ventilation. The blower
size required to reduce vapor concentration in specific sized tanks
is provided in Table 4-1. Occupational Safety and Health Adminis-
tration (OSHA) regulations require solvent vapor concentrations to be
below a specified level. Since this cannot be achieved by means of
ventilation, air-supplied respirators must be worn by workers at all
times.
In addition to ventilation requirements, spark-proof and
explosion-proof equipment should be used. Smoking, matches, flames
or sparks of any kind should be prohibited. These precautions
represent the minimum steps to be taken to ensure worker safety.
Special considerations need to be made for specific paint systems.
40
-------
Table 4-1
BLOWER CAPACITIES REQUIRED TO MAINTAIN VAPOR
CONCENTRATION WELL BELOW LOWER EXPLOSIVE LIMIT
Volume of Tank Required Blower Size*
(Gallons) (CFM)
500-5,000 1,000
5,000-20,000 2,000
20,000-100,000 5,000
100,000-250,000 10,000
500,000 15,000
1,000,000-2,000,000 20,000
*Suction type
Source: Ameron Company
41
-------
Ventilation is also important for promoting evaporation of sol-
vent from the paint film, thereby aiding the curing process. Impro-
perly cured coatings may retain solvent residues that can subsequently
enter the water and introduce taste, odor, or toxicity to the water
supply (Wellington, 1971).
In addition to the hazards associated with the solvents, the
film forming ingredients of the paint may also present a hazard to
the applicator. There are several hazards associated with the use of
coal tar based coatings. The National Institute for Occupational
Safety and Health (NIOSH) has published a criteria document on the
effects of exposure to coal tar (NIOSH, 1977). Exposure has been
reported to produce phototoxic effects such as skin erythema, burning
and itching, photophobia and conjunctivitis. In addition, exposure
can increase the risk of lung and skin cancer. NIOSH recommends an
exposure limit of 0.1 mg/m^ of the cyclohexane-extractable fraction
of the sample. This is of particular concern during application of
the hot applied coal tar enamel because volatile constituents of the
coal tar are released at the temperature of application.
The strongly alkaline amine type catalysts used in epoxies are
irritating to some people (Berger, 1976). The vinyl paints may
contain free vinyl chloride, a known carcinogen. Urethane coatings
contain free toluene diisocyanate or isocyante monomer which will
cause severe skin irritation (Berger, 1976).
A hazard also exists in the use of metallic zinc coatings.
Exposure to the zinc oxide fumes can produce metal-fume fever.
42
-------
This condition is not fatal but causes severe discomfort which lasts
a day. The American Conference of Governmental Industrial Hygienists
and the Occupational Safety and Health Administration established a
zinc oxide fume concentration exposure limit of 5 mg/nH for workers.
To ensure workers' safety, air-supplied respirators must be worn
during the metallizing procedure.
Wax seems to be the least hazardous of available coatings to
apply. The formulation commonly used contains petroleum solvents
such as kerosene. No special protective equipment is used during
application.
Application of the coatings may also contribute to air pollu-
tion. Solvents used in the coatings are often photochemically
reactive and contribute to the photochemical smog problem. In
California, where there is a serious pollution problem, substitution
of non-photochemically reactive solvents has sometimes adversely
affected paint performance (Boyd, 1973). Visible emissions and odors
emanating during the shop application of hot applied enamel to pipes
has resulted in the abandonment of the use of hot applied enamel for
this purpose in some locations (Lingle, 1978; Klpin, 1978).
43
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5.0 TOXICOLOGICAL CONSIDERATIONS OF THE MATERIALS USED AS LININGS
Factors affecting the health risks to the general public asso-
ciated with a particular material used for lining pipes or tanks that
are part of a potable water distribution system include the following:
• those compounds contaminating the water as a result of con-
tact with the lining material,
• the rates with which these compounds leach into the water,
including constancy of the leaching process over time,
• the water solubilities of those compounds that do leach,
• the effect of chlorination, ozonation, pH, dissolved solids,
etc., on the potential for leaching and on leaching rates,
• the concentrations in the water of those compounds that do
leach (both in the system and at the tap),
• the rates of decomposition and the decomposition products of
the detected compounds,
• the reactions of leached compounds with compounds already
present in the water (e.g., resulting from disinfectant
techniques),
• the characteristic synergistic, antagonistic, and additive
interactions of the compounds present,
• the potential for adverse health effects due to ingestion
and metabolism of the compounds,
• the relative risk of exposure to these compounds in water
(i.e., compared with contributions to the body burden from
other exposure sources), and
• the relative risk presented by utilization of the lining
material being investigated versus that inherent to alter-
native lining materials.
In the sections that follow, the currently available data items
that describe many of these factors are presented.
44
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5.1 Compounds Identified in Potable Water and Attributed to the Use
of Lining Materials
Data are available from one investigation, which identified
numerous compounds in potable water and attributed their presence to
the utilization of a coal tar pitch coating in a ground storage water
tank (McClanahan, 1978). Sampling of the water in the 750,000 gallon
Bayou Casotte tank in Pascagoula, Mississippi, was precipitated by
repeated taste and odor complaints after the coating, Bitumastic
Super Tank Solution (manufactured by Koppers Company, Inc.), had been
applied. Although the coating was dried and the tank was disinfected
and refilled four times, there were taste and odor complaints and/or
unacceptable bacteria counts after the first three times (Compton,
1978). Eighteen compounds were identified in the first samples,
obtained approximately 5 months after the coating was applied (Table
5-1)• The water from which these samples were obtained had a contact
time* of 6 days, while the estimated retention time* was 6.1 days.
The second sampling occurred approximately 3.5 months after the first
and revealed the presence of 12 compounds. Samples were acquired from
the top of the tank, as for the first sampling; however, the sample
^Contact time is the maximum period of time that the water could have
been In contact with the tank (i.e., time elapsed from the beginning
of flow into the tank for refilling purposes until the sample was
obtained), while retention time is the estimate of actual residence
time for the water in the tank (i.e., rate of turnover as calculated
by dividing the volume of the tank by the rate of discharge from the
overflow valve). Retention time is normally the measurement of
choice, but in this case contact time was calculated because only
one measurement of the rate of discharge from the overflow valve was
made. As this rate can fluctuate dramatically from day to day, it
was felt that, for accuracy, contact time would be more appropriate.
45
-------
TABLE 5-1
ESTIMATED CONCENTRATIONS OF COMPOUNDS DETECTED IN THE WATER
IN THE BAYOU CASSOTTE GROUND STORAGE WATER TANK
USING GAS CHROMATOGRAPHY/MASS SPECTROMETRY
Compound
naphthalene
methyl naphthalene
biphenyl
acenaphthene
dibenzofuran
fluorene
phenan threne/ anthracene
carbazole
bromoform
C alkylchlorobenzene
indene
C alkylbenzene
an thr aquinone
methyl benzofuran
quinoline
methyl styrene/indan/indene
methylene phenanthrene/methyl
phenathrene
pyrene
2 , 5-diethyltetrahydrof uran
dimethyl naphthalene
fluoranthene
Sample Date and Concentration (ng/1)
9/6/77
A B
5.4 6.7
0.75 1.4
0.21 0.40
2.8 4.6
3.1 5.0
3.4 5.1
8.7 9.3
0.70 1.3
<10 <10
<50 <50
< 2.0 < 10
< IQ < iQ
<10 <10
< iQ < 10
<10 <10
<10 <10
1/16/78
A
0.63
1.3
1.1
1.5
4.5
0.44
<10
<50
<10
<10
<10
11
2/21/78
A
1.3
<1
<1
3.1
2.3
2.9
14
3.9
2.7
2.3
<1
<1
1.7
1.2
2.2
1.2
2.7
B
2.7
1.3
<1
8.0
6.3
8.0
35
11
7.3
8.3
1.0
<1
2.6
4.0
7.0
2.7
9.7
A Sample obtained from a valve approximately 3 feet above the bottom
of the tank
B Sample obtained from the top of the tank
Source: Adapted from McClanahan, 1978.
46
-------
from the top of the tank was lost before analysis. Contact and
retention times for this sample were 2.8 and 58 days, respectively.
Analysis of the third sampling, performed without draining the water
from the tank after the second sampling, indicated the presence of 17
compounds. For these samples contact and retention times were 39 and
58 days, respectively. At the time the third pair of samples was
obtained, samples of the raw water were taken prior to entry of the
water into the tank. None of the compounds detected in any of the
samples acquired from within the tank were present in the raw water
samples.
It was suggested that the relatively high concentrations detec-
ted in the 2/21/78 sample obtained from the top of the tank may have
resulted from the action of convection currents in the water. Prior
to this sampling, the flow of water through the tank had ceased for 4
days. During this time solar heat would have been transferred from
the walls of the tank to that water immediately adjacent to the
walls, thereby increasing its temperature. This water, which under
the conditions of no forced flow would contain the highest concentra-
tions of any materials leaching from the coating, would tend to rise
to the top of the tank. As a result, it might be expected that the
leached compounds would be present in higher concentrations toward
the top of the tank.*
*N.B. Flow was resumed 1 hour prior to sampling. This flow was not,
however, considered sufficient to have completely disturbed the ele-
vated concentrations at the top of the tank before the samples were
obtained.
47
-------
In a study in Portland, Oregon, water samples were obtained from
the source and the terminal point of a coal tar (type unspecified)
lined pipe, 24 inches in diameter and 2.43 miles in length (Robeck,
1978). Table 5-2 indicates the compounds and the concentrations
detected at both the source and at the end of the pipe. This was the
only other report available of compounds detected in drinking water
that were attributed to leaching from coal tar based lining materials.
The data cited do provide evidence for leaching from the coal
tar linings into the water, and some compounds have been identified.
However, there are no Indications of leaching rates, the fluctuations
of those rates, the effects of water quality on leaching rates, the
solubilities of the leached compounds, the extent and products of
decomposition of the leached compounds, the ultimate concentrations
to which the general public might be exposed via drinking water, the
interactions between the compounds both before and after human expo-
sure, or the potential for adverse effects on human health*
Table 5-3 lists the compounds identified in the Bayou Cassette
ground storage water tank and indicates those for which atmospheric
detection has been reported. Data concerning quantification of these
compounds in the air are, at best, limited. Table 5-4 lists those
compounds, detected in the Bayou Cassette ground storage water tank,
for which actual atmospheric concentrations have been found.
No data revealing total dietary intake of the compounds detected
in the Bayou Cassette ground storage water tank were found. There
48
-------
TABLE 5-2
COMPOUNDS DETECTED IN THE WATER SAMPLES OBTAINED IN PORTLAND, OREGON
Concentration (ng/1)
Compound A B ^
phenanthrene ^3 3225
1-methyl phenanthrene - NQ
2-methyl phenanthrene - NQ
fluoranthene <1 572
pyrene <1 671
chrysene - 32
benzo(b)fluoranthene <1 4
fluorene - NQ
acenaphthene/biphenyl - NQ
A At the source
B At the end of 2.43 miles of coal tar lined pipe
NQ Not quantifiable
Source: Robeck, 1978.
49
-------
TABLE 5-3
ALTERNATE SOURCES OF THOSE COMPOUNDS IDENTIFIED IN THE
BAYOU CASSOTTE GROUND STORAGE WATER TANK
COMPOUND
naphthalene
methyl naphthalene
biphenyl
acenaphthene
dibenzofuran
fluorene
phenanthr ene / an thr acene
carbazole
bromoform
C alkylchlorobenzene
indene
C alkylbenzene
anthraquinone
methyl benzofuran
quinoline
methyl strene/indan/ indene
methylene phenanthrene/methyl
phenathrene
pyrene
2,5-diethyltetrahydrofuran
dimethyl naphthalene
fluoranthene
SOURCES
A
/
J
/
B
*
/
S
/
/
/
/
'
Cl
*
S
J
/
/
^
/
^
C2
*
^
J
/
^
^
C3
^
CA
J
A Compound is a component of the particulate polycyclic organic matter
(PPOM) emitted by coal-fired residential furnaces, which are the
largest source of PPOM emissions from heat generation. The compound is
also emitted through incineration, open burning, and motor vehicle exhaust.
B Among PPOM identified in 1961 by Sawicki and co-workers as being present
in air or emitted to the air.
C Reported by Sawicki and co-workers and/or Hartwell and Shubik as being
present in air (C,), tobacco smoke (C-), gasoline exhaust (C»), or
diesel exhaust (C,).
Source: National Environmental Research Center, 1975.
50
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TABLE 5-4
ATMOSPHERIC CONCENTRATIONS (DETECTED IN THE U.S.) REPORTED FOR THOSE
COMPOUNDS IDENTIFIED IN THE BAYOU CASSOTTE GROUND STORAGE WATER TANK
COMPOUND
CONCENTRATION
(ng/m )
methyl naphthalene
acenaphthene
pyrene
fluoranthene
134 - 3,100,000
0.0 - 2.5
0.1 - 36
5.1 (average)
5.5 (average)
Source: National Environmental Research Center, 1975.
51
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were data available concerning the concentrations of three of the
compounds (i.e., phenanthrene, fluoranthene and pyrene) In certain
foodstuffs, largely smoked meat and fish (Santodonato et al., 1979).
The concentrations of phenanthrene, fluoranthene, and pyrene found in
coconut oil were 51, 18, and 15 ppb, respectively; while the range
(in ppb) detected for each in smoked fish was 4.1 to 52, 1.8 to 12,
and < 0.5 to 4.4. All these were also detected in smoked meats/meat
products, and the concentrations (ppb) were: detected to 104 for
phenanthrene, 0.6 to 49 for fluoranthene, and 0.5 to 42 for pyrene.
As is apparent, there is a minimum of data available indicating
atmospheric and total dietary concentrations of these compounds.
The only other data available concerning leachates in potable
water systems from materials used in the system are indicated below.
In a determination of the potential for migration of vinyl chloride
into water from polyvinyl chloride pipe, Dressman and McFarren (1978)
detected low concentrations of vinyl chloride in four of five water
distribution systems sampled* The five sampling sites were selected
because they were representative of climatic extremes, and because
data concerning age, length, and size of the pipes were available.
Although only one sample was sufficiently high to be verified by mass
spectrometry, the concentration as determined by gas chromatography
ranged from 0.03 to 1.4 g/1. The data were limited but water in the
newest, longest system had the highest concentration of vinyl chlor-
ide, while water from two 9-year-old systems had the lowest concentra-
tions.
52
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5.2 Amelioration of Potential Toxicological Problems
In the introduction to this chapter, a list was presented indi-
cating those broad categories of data that would be essential for a
thorough evaluation of the hazards presented by water contaminants
derived from materials on distribution system contact surfaces* The
first item (i.e., identification of those compounds contaminating the
water as a result of contact with a lining material) is the only one
that is addressed even minimally by the available data.
Currently, there are a limited number of evaluations that are
being conducted by government or private laboratories that are
applicable to the problem being reviewed. The tests being performed
are essentially qualitative and quantitative leaching determinations*
Table 5-5 indicates the laboratories performing the analyses and the
material(s) being analyzed. Unfortunately, data generated by these
studies were not available at the time this report was prepared.
TABLE 5-5
QUALITATIVE AMD QUANTITATIVE LEACHING EVALUATIONS
CURRENTLY IN PROGRESS
MATERIAL(S) BEING EVALUATED
Coal Tar Epoxy Paint
Organic Coatings
Asphalt Seal Coat
Coal Tar Pipe Lining
Asbestos Cement Pipe
Plastic Pipe
EVALUATING LABORATORY
Corps of Engineers Laboratory
Champaign, Illinois1
National Association of Corrosion
Engineers
Katy, Texas2
Southern Research Institute
Birmingham, Alabama^
Municipal Environmental Research
Laboratory (EPA)
Cincinnati, Ohio
Municipal Environmental Research
Laboratory (EPA)
Cincinnati, Ohio
Olson, 1977.
Municipal Environmental Research 2
Laboratory (EPA) Dlllard, 1978.
Cincinnati, Ohio Barrett, 1977.
53
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6.0 CONCLUSIONS AND RECOMMENDATIONS
The water supply industry represents a relatively small portion
of the total market for coal tar based coatings. One of the two
suppliers of hot applied coat tar enamel stated that the water supply
market accounted for approximately 10 percent of the company's sales
of the enamel. The total value of coal tar products supplied to the
water supply industry is estimated at two million dollars annually.
On the basis of the information obtained from industry represen-
tatives and presented in this report, it is concluded that there is a
trend away from the use of hot applied coal tar enamel by the water
supply industry. Reasons for this include:
• difficulty in finding experienced applicators,
• difficulty in complying with OSHA and EPA regulations
regarding control of fumes during application,
« the availability of alternative linings, and
• increased awareness of a potential for leaching of toxic
components of coatings into the water supply.
The use of a coal tar based epoxy paint for lining steel water
pipes may increase because of a recently issued standard on coal tar
epoxy for this use by the American Water Works Association. However,
non-coal tar based epoxy is also used to line steel water pipes.
Although alternatives to coal tar based coatings are available
and widely used, as with the coal tar based coatings, the potential
for introduction of toxic substances into the water supply has not
been adequately determined. The extraction tests that are currently
-------
utilized to evaluate the acceptability of coatings for use on potable
water supply contact surfaces are inadequate* They assess total
leachates only; they do not provide a qualitative or quantitative
indication of the extent of leaching from coatings.
Several research programs are currently underway which may pro-
vide data on the leaching characteristics of selected coal tar based
linings and other materials that may be used for potable water
distribution system contact surfaces; however, the results of these
programs are not yet available.
In order to be able to identify those materials suitable for use
as potable water contact surfaces and to provide guidance to utilities
in upgrading existing systems or installing new ones, the following
should be addressed:
• Develop protocols for determining the extent of leaching
from the various materials applicable as coatings;
• Determine the qualitative and quantitative nature of the
leachates under the expected conditions of use;
• Evaluate the individual and collective chemical reactivities
of the leachates;
• Establish a monitoring system designed to determine the
extent of leaching in water distribution systems currently
being utilized; and
• Develop a toxicological data base tailored to facilitate
comparisons of the various materials (i.e., estimations of
relative risk).
55
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BIBLIOGRAPHY
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56
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BIBLIOGRAPHY (Continued)
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57
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BIBLIOGRAPHY (Continued)
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Dillard, J., Technical Activities Director, NACE Headquarters,
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Dressman, R.C. and E.F. McFarren, "Determination of Vinyl Chloride
Migration from Polyvinyl Chloride Pipe into Water." Journal AWAA,
PP. 29-30. January 1978.
Enoch, A., Pennsbury Coatings, New Britain, Pennsylvania. Personal
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Fair, W.F., Jr., "Properties, Specifications, Tests and Recom-
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Corrosion, V. 12, pp. 579-587. November 1956.
58
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BIBLIOGRAPHY (Continued)
Fair, W.F., Jr., "Properties, Specifications, Tests and Recom-
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Corrosion, V. 12, pp 605t-610t. December 1956.
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Faustel, Gilbert M., Chief, Water Supply Design and Construction
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Koppers Company, Pittsburgh, Pennsylvania. February 21, 1973.
Faustel, G.M., Chief, Water Supply Design and Construction Section,
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to R.C. Schwarz, Organic Materials Division, Koppers Company. Inc.
September 24, 1975.
Frye, S.C., "Epoxy Lining for Steel Water Pipe," Journal of AWWA,
V 66, No. 8, pp. A98-501. August 1974.
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Capacity," Corrosion, September 1946.
Garrett, G.H., Ameron Company, Brea, California. Pesonal communi-
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Personal communication, January 1978.
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Harper, Chicago Bridge and Iron, Oak Brook, Illinois. Pesonal
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Journal AWWA, V. 32, No. 10, October 1940.
59
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BIBLIOGRAPHY (Continued)
Higgins, Mike, Cast Iron Research Institute. Personal communi-
cation, 1977.
Houser, B., Universal Tank Company, Indianapolis, Indiana. Personal
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Husselbaugh, Bill, Industrial Coatings, Inc. Personal communi-
cation, 1978.
Irish, National Association of Pipe Coating Applicators. Personal
communication, 1977.
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Tanks." Journal AWWA V. 62, No. 9, pp. 577-584, September 1970.
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1, 1975.
Kemp, Woodrow, Personal communication, 1978.
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Kimm, Victor J., Deputy Assistant Administrator for Water Supply,
Letter to Mr. Melvin Mitchell, City of Pascagoula, Mississippi,
dated August 24, 1977.
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and Installation." Journal AWWA, V. 65, No. 12, pp. 786-788.
December 1973.
Kipin, Peter, CST Pipeline Service Company, Pittsburgh, Pensylvania.
Personal communication, 1978.
Kraft, Owens-Corning Fiberglass, Columbia, Maryland. Personal
communication, February 1978.
Lawrence, Alonzo Wm., Letter to Carl Kessler, Economist, EPA Office
of Water Supply, December 12, 1977.
Leary, C., Leary Construction Co., Cincinnatti, Ohio. Personal
communication, January 1978.
60
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BIBLIOGRAPHY (Continued)
Lingle, Bob, Gaido-Lingle Co., Inc., Houston, Texas. Personal
communication, February 1978.
Lipscom, Engard Coatings Corp. , Huntington Beach, California.
Personal communication, January 1978.
Lombardo, J., ICI America Co., Wilmington, Delaware. Personal
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1978.
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61
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BIBLIOGRAPHY (Continued)
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62
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BIBLIOGRAPHY (Continued)
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63
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BIBLIOGRAPHY (Continued)
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64
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APPENDIX A
DESCRIPTION OF NONCOAL TAR BASED LINING SYSTEMS
65
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Epoxy Paint Systems
Epoxy paints have been used on the interior surfaces of potable
water tanks and pipelines with good results when properly formulated
and applied. The resin for these coatings is proudced by the polymer-
ization of epichlorohydrin and bisphenol A. As the proportionate
amount of bisphenol A is increased, the resin becomes a hard, high
molecular weight resin suitable for use in water immersion service.
There are two types of epoxy coatings, the single component and the
two-component.
A single component epoxy consists of an epoxy vehicle mixed with
pigments. The vehicle consists of a high molecular weight epoxy
resin reacted with a minimum amount of drying oil and modified with a
reactive resin in suitable solvents. The resin dries by oxidation
and polymerization.
This system adheres strongly to steel surfaces and exhibits
satisfactory cohesion between the paint coats. In addition, it
exhibits low permeability to water and oxygen. Technical data
associated with a typical single component epoxy paint are included
in Appendix B, Table B-10.
The two-component epoxy paints consist of a base and a hardener.
The base contains the epoxy resin, pigments and solvent; the hardener
is usually a polyamide or an amine plus a solvent. Phenolics have
also been used as the curing agent or hardener.
67
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The coating films of this system dry hard, with excellent adhe-
sive qualities and low permeability to oxygen and water. Specifica-
tions for a typical two-component epoxy paint system are contained in
Appendix B, Table B-ll.
The draft AWWA standards for painting storage tanks (AWWA, 1977)
specifies a two-component epoxy paint system. Two systems have been
included. One is a three-coat system conforming to Military Specifi-
cation MIL-P-24441 and the other is a two-coat system conforming to
Military Specification MIL-C-4556.
Epoxy linings in pipelines have been shown to sustain high flow
coefficients which enable smaller diameter pipes to be used for an
equivalent flow capacity. Also, the thinner lining (0.008 inches as
compared with 0.094 inches for coal tar and 0.30 inches for cement
mortar) Is an advantage for the epoxy, allowing increased flow capa-
city for a given diameter pipe (Cook, 1977).
Vinyl Paint
Vinyl paint resins are solutions of vinyl chloride-vinyl acetate
copolymer and a hydroxyl compound such as vinyl alcohol and/or a
carboxyl compound such as maleic acid. Vinyls are one of the most
popular linings used in water tanks. In long-term immersion tests,
all vinyl systems have shown outstanding performance when properly
applied (Keane, 1975). Vinyls are inert in water, and provide a
hard, tough, smooth film with low moisture absorption properties
(Bureau of Reclamation, 1976).
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The draft proposed AWWA standard for painting potable water
storage tanks (AWWA, 1977) includes two interior vinyl paint systems.
One is a five-coat vinyl system. The other is a four-coat system
based on a high solids vinyl resin.
The five-coat system consists of a primer of basic zinc chromate
vinyl butyral wash coat and four coats of a vinyl resin paint. Two
of the vinyl resin coats are intermediate paint formulations and two
coats are finish paint formulations. Three variations of the five-
coat system are described in the draft proposed standard. The
variations relate primarily to the composition of the finish coat
and to the final film thickness.
The wash coat consists of two components which are mixed together
prior to use. One component contains an alcohol solution of butyral
resin pigmented with basic zinc chromate which acts as a corrosion
inhibitor. The second component contains an alcohol solution of
phosphoric acid which reacts with the vinyl resin, the pigment, and
the steel. An approximate summary of the wash coat composition is
presented in Appendix B, Table B-12. A typical composition of the
vinyl resin paint used in this system is presented in Appendix B,
Table B-13.
The four-coat system is a high solids vinyl formulation developed
by the Bureau of Reclamation. It is called VR-3 paint (Bureau of
Reclamation, 1967). Each coat uses the same paint; however, the
thickness of each coat is different. The total dry film thickness is
69
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0.005 inches. Three four-coat systems are described in the draft
proposed standard. They differ only in the color of the finish coat*
The vehicle of the vinyl paint used in this system is a solution of
vinyl chloride-vinyl acetate-maleic acid tripolymer resin. The
remainder of the resin is vinyl chloride-vinyl acetate copolymer
or partially hydrolyzed copolymer. A plasticizer such as dioctyl
phthalate is used. Solvents that may be used include methyl isobutyl
keytone and toluene.
Wax Coatings
The AWWA standard for painting steel tanks (AWWA, 102-64) in-
cludes two wax coating systems that may be used inside water storage
tanks. These are a hot applied wax and a cold applied wax system*
Both are blends of petroleum waxes and oils containing proprietary
active corrosion inhibitors. The characteristics of the coating are
specified in Appendix 8, Table B-14.
Chlorinated Rubber Coatings
Chlorinated rubber is made by exposing natural rubber to chlor-
ine gas until it contains approximately 67 percent chlorine. The
resultant resin is hard and brittle and must be plasticized with
other resins or with linseed oil or alkyd resin. These plasticizers
make the paint more flexible and adherent to steel but also less
resistant to water.
70
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The chlorinated rubher vehicle used contains 50 to 60 percent by
weight of chlorinated rubber and the remainder is solid or liquid
chlorinated paraffin. Older formulations contained chlorinated
biphenyls or polyphenyls. These compounds are no longer allowed
to be used*
High-build systemn are formulated to allow a 0.005 to 0.006
inch dry thickness using three coats. A typical composition of a
high-build chlorinated rubber paint that may be used in water storage
tanks is included in Appendix B, Table 15.
Metallic Sprayed Zinc
Metallic sprayed zinc is 99.9 percent pure zinc wire that has
been melted, atomized in high pressure air, and blown onto the steel
surface as a 0.010 inch thick coating. It provides long service life
and freedom from rust contamination. Specialized application skills
and equipment are required and the surface of the steel must be blast
cleaned to white metal before application. These requirements make
this coating relatively expensive (Bureau of Reclamation, 1976)
Miscellaneous Paint Systems
Included in this section are paint systems which have been re-
ported to be suitable for use in potable water service but which have
not received wide use for various reasons. Some of these systems
are relatively new and may be used more extensively in the future.
Others have not performed well and have been abandoned.
71
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Asphalt Based Linings
Asphalt is a term used to describe a variety of dark resinous
materials; some are natural and some are by-products of petroleum
cracking or distillation. Standards for asphalt coatings and linings
customarily specify petroleum asphalt (Seymour, 1959). However,
Koppers Company supplies asphalt coatings containing the natural
resin, gilsonite. Gilsonite has been listed by the FDA as acceptable
for use as a food contact surface (CFR 21, 1977).
Asphalt and asphalt enamels show less resistance to water
absorption than coal tar enamels and pitches. They exhibit a rapid
increase in water absorption with time whereas the water absorption
curve for coal tar enamel does not increase with time. The rising
water absorption rates for asphalt indicate eventual failure (Fair,
1956). For this reason, asphalt coatings are not widely used as a
protective lining for new steel water tanks or pipelines. The AWWA
does not include asphalt coatings in their standards for lining water
pipelines or storage tanks. Asphalt based coatings are used to
recoat existing asphalt lined tanks (Wagner, 1978). They are also
used as a seal coat over cement mortar linings in cast iron and
ductile iron pipe. In this service the coating serves primarily as a
seal to retain the moisture in the cement long enough to effect
proper curing.
Phenolic Based Linings
A lead aluminum phenolic paint system and a zinc phenolic system
were listed in the AWWA standard for painting tanks (AWWA, 1964).
72
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These paints received a poor rating in an evaluation of coatings for
water tank interiors (Keane, 1975). They are not included in the
draft proposed revision to the AWWA standard for painting tanks
because of a lack of wide use*
Zinc Rich Linings
Zinc rich paints are composed of an organic or inorganic vehicle
with a high zinc dust content. In organic vehicles the zinc dust
content ranges from 80 to 95 percent by weight of total nonvolatile
content. Inorganic zinc rich vehicles contain upwards of 95 percent
by weight of zinc dust. The paints are formulated to provide hard,
tough, abrasion resistant protection to steel. Rust inhibition is
also provided due to the galvanic protection provided by the zinc.
The zinc rich paints normally require a near-white metal blast
cleaned surface and are applied in one coat to a 0.002 to 0.005 inch
dry film thickness over the cleaned steel. Often they are used as
primers and top coated with another paint. The zinc coating requires
a 7-day drying period (SSPC, 1973).
In a water tank test, zinc dust-zinc oxide paints, in both phenol-
ic and polyamide epoxy vehicles, were in good condition after 7 years
(Keane, 1969).
Powder Linings
Epoxy powder coatings are also beginning to be used for lining
pipelines. The powder is sprayed onto a heated pipe surface. The
73
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hot pipe melts the powder which then forms a film which is fused onto
the pipe. A major advantage of the powder coatings is the elimina-
tion of solvents which have been found to create occupational health
hazards and air pollution problems (Lingle, 1978).
-------
APPENDIX B
TYPICAL COATING CHARACTERISTICS
NOTE: The typical coating characteristics included herein are not
sufficient by themselves to be used to specify a coating
system. They are, however, an important part of the complete
specification.
75
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Table B - 1
Characteristics of AWWA Coal Tar-Enamel
Test
Softening Point, ASTM D36
Filler (ash), ASTM D2 71
Fineness filler, through
200 mesh, ASTM D546
Specific Gravity at 25C,
ASTM D71
*Penetration, ASTM D5
at 77F 100-g weight
5 sec
at 115F 50-g weight
5 sec
High temperature test
at 160F (sag) , AWWA
C203, Sec. 2.8.8
Low-temperature test
at -10F (cracking)
AWWA C203, Sec. 2.8.9
Low-temperature test
at -20F (cracking)
AWWA C203, SEC. 2. 8. 9
**Deflection test (Initial
heating), AWWA C203,
Sec. 2.8.10
Initial crack
Disbonded area
**Deflection test (after
2-hr heating) , AWWA
C203, SEC. 2.8.11
Initial Crack
Disbonded area
**Impact test at 77F
650-g ball, 8-ft. drop,
AWWA C203, Sec. 2.8,13
Direct impact,
disbonded area
Indirect Impact,
disbonded area
"""Peel test, AWWA C203,
Sec. 2.8.12
Enamel Type I
Minimum
220F
25%
90%
1.4
5
12
-
-
N/A
0.5 in.
-
0.3 in.
-
-
-
Maximum
240F
35%
-
1.6
10
30
2/32 in.
None
N/A
-
5 sq. in.
-
8 sq. in.
16 sq. in.
6 sq. in.
No peeling
Enamel Type II
Minimum
220F
25%
90%
1.4
10
15
-
N/A
-
0.8 in.
-
0.6 in.
_
-
-
Maximum
240F
35%
.._
1.6
20
55
2/32 in.
' N/A
None
_
3 sq. in.
_
5 sq. in.
10 sq. in.
2 sq. in.
No Peeling
*For static conditions above 5F use enamel with 5-10 penetration at 77F; below 5F and above
-10F use 10-15 penetration; and below -10F and above -20F use 15-20 penetration enamel.
("Static conditions" are those conditions under which the pipe is not being handled.)
**Choice of bond testing methods by deflection (before heating), by deflection (after 2-hr.
•heating), or by impact shall depend upon laboratory equipment available.
+Type I enamel in the 5-10 penetration range at 77F shall be tested with synthetic primer, Type B.
N/A - Not Applicable
SOURCE: AWWA C203-73.
77
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TABLE B-^2
AWWA REQUIREMENTS FOR COLD APPLIED TASTELESS AND ODORLESS
COAL TAR BASED PAINT SUITABLE FOR LINING POTABLE WATER STORAGE TANKS
CHARACTERISTIC
SPECIFICATION
Viscosity - seconds per 100
revolutions @ 77°F
(ASTM D-562)
Density, Ib/gallon
Ash Content, % by weight
Flash Point (ASTM D-56)
Distillate, % by weight
(ASTM D-20)
60 -75
8.7 - 9.7
0.5 maximum
70°F minimum
45% maximum
Source: AWWA, 1964
78
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TABLE B-3
COMPOSITION OF COAL TAR EPOXY COATING SUITABLE FOR
USE IN POTABLE WATER STORAGE TANKS
INGREDIENT
% BY WEIGHT
COMPONENT ONE
Coal Tar Pitch
Polyamide Resin* [2,4,6-Tri-
(dimethylamino methyl phenol)]
Magnesium Silicate (ASTM D-605)
Xylene (ASTM D-364)
Ethyl Alcohol (95% denatured)
Gelling Agent
Catalyst
34.0 - 36.0
11.0 - 12.0
30.0 - 32.0
18.0 - 21.0
0.9 - 1.1
1.5
1.2 - 1.3
COMPONENT TWO
Liquid Epoxy Resin (a di-epoxide
condensation product of bisphenol
A and epichlorohydrin with
terminal epoxide groups)
Approximately 1 part of
component 2 to 4 parts
of component 1 by weight
Source: SSPC, 1973, with permission.
79
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TABLE B-A
SPECIFICATION FOR COAL TAR PITCH
USED IN COAL TAR EPOXY PAINT
Characteristic
Specification
Softening Point, °C (ASTM D-36)
Ash, % by weight (ASTM D-271)
Benzene insolubles, % by weight
(ASTM D 367)
Volatiles, % by weight (ASTM D-20)
Under 250°C
Under 300°C
70 minimum, 75 maximum
0.5 maximum
18.9 maximum
0
5 maximum
Source: SSPC, 1973, with permission
TABLE B-5
SPECIFICATION FOR POLYAMIDE RESIN
USED IN COAL TAR EPOXY PAINT
Amine value*
330 minimum, 360 maximum
Source: SSPC, 1973, with permission.
*Amine value is defined as the milligrams of potassium hydroxide equiva-
lent to the amine alkalinity present in one gram of sample. It is
determined by a potentiometric titration with standard perchloric acid,
80
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TABLE B-6
SPECIFICATIONS FOR GELLING AGENTS C AND D
USED IN COAL TAR EPOXY PAINT
Characteristic
Gelling Agent C
Gelling Agent D „
Chemical Form
Crystalline Form
Bulking value
Density
Refractive index
Absorbed water, /
Surface area
organic derivative of micro-crystalline
magnesium montmorillonite hydrated magnesium
powder silicate powder
— * Colloidal, rod
shaped, submicron
particles obtained
by processing
chrysotile
15+2 pounds per gallon
it
*
3.0 maximum
*
2.2 gm/cc
1.5
1.0
68 sq m/gm
*— means no specification.
Source: SSPC, 1973, with permission.
81
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TABLE B-7
SPECIFICATIONS FOR COMPONENT A OF
COAL TAR EPOXY PAINT
Characteristic Specification
Viscosity, poise @ 25°C* 160
Konvolatiles, %* 77 minimuin
Source: SS?C, 1973, with permission.
TABLE 3-8
SPECIFICATIONS FOR COMPONENT B OF
COAL TAR EPOXY PAINT
Epoxide Equivalent (ASTM D-1652) 180 minimum, 200 maximum
Non volatile content, % one hour
@ 105 + 2°C 99 minimum
Color, (Gardner) (ASTM D 1544) 5 maximum
Specific gravity, 25°C/25°C 1.15 minimum, 1.18 maximum
Vicosity, poises @ 25°C 100 minimum, 160 maximum
(Brookfield)
*Test procedures are described in reference.
Source: SSPC, 1973, with permission.
82
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TABLE B-9
PHYSICAL PROPERTIES OF COAL TAR EMULSION
PROPERTY
Specific Gravity
pH
Viscosity, Centistokes
(ASTM D-562)
Vapor Pressure, Reid @ 25°C
(ASTM D-323
Flash Point (ASTM D-92)
Cleveland Open Cup
Tag Open Cup
Firepoint
Resistance to flow with heat
(Slide Test) (ASTM D-466)
Sag
Electrical Insulation
Resistivity per cm thickness
One mil thickness resists
TYPICAL VALUE
1.2
6.2
518
3 psi
131°C
131°C
314 °C
No slide to 80°C
None at temperature to
80°C
3300 ohms
600 volts
Source: Briggs Bituminous Composition Co.
83
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TABLE B-10
A SINGLE COMPONENT EPOXY PAINT
Composition Pigment - pure brown oxide
Vehicle - modified epoxy
Viscosity @ 25°C 80-115 seconds, #4 Ford cup
Thinning Not to exceed 10% by volume
Recommended thinner Xylol
Solids by volume 38-39%
Solids by weight 60.0 + 2%
Source: Sterling Division of Reichhold Chemicals, Inc.
-------
TABLE B-ll
TWO-COMPONENT EPOXY PAINT
HI-BUILD EPOXY UNDERCOAT
Composition;
Solids by weight - 75% Pigment - Titanium dioxide and
reinforcing pigments - 46%
Vehicle - epoxy resin solids - 29%
Solvent by weight - 25%
Solids by volume - 54-56%
Viscosity - 86-94 KU
EPOXY HARDENER
Composition;
Solids by weight - 66% Pigment-reinforcing pigments - 47%
Polyamide solids - 19%
Solvent by weight - 34%
Solids by volume - 46-48%
Viscosity - 88-94 KU
MIXED MATERIAL DATA
Solids by weight 69.5 + 0.5%
Solids by volume 50 - 51%
Thinning Not to exceed 10% by volume
Drying time 16-24 hours @ 21°C
Pot life @ 21°C 8-10 hours
Source: Sterling Division of Reichhold Chemicals, Inc.
85
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TABLE B-12
BASIC ZINC CHROMATE VINYL BUTYRAL WASH COAT
Pigment Base % by weight
Polyvinyl butyral resin 9.2
Basic zinc chromate 8.8
Magnesium silicate 1.3
Lampblack 0.1
Butyl alcohol, normal 20.5
Isopropyl alcohol* 57.7
Water 2.4
Acid Dilutent
85% Phosphoric acid 18.5
Water (maximum) 16.5
Isopropyl alcohol* 65.0
*
Isopropyl alcohol and water in the pigment base may be replaced by
ethyl alcohol, 61,3 parts. In the acid component it may be replaced
by 67 parts of ethyl alcohol.
Source: SSPC, 1973, with permission
86
-------
TABLE B-13
TYPICAL VINYL RESIN PAINT
Ingredient
Intermediate Coat
% By Weight
Finish Coat
% By Weight
Pigment:
Titanium Dioxide
Aluminum Powder
12.0
0
o
6.7
Vehicle :
**
Vinyl Resin
Vinyl Resin B
Tricresyl Phosphate or
Dioctyl Phthalate
Methyl Isobutyl Ketone
Toluene
8.0
8.0
3.0
34.5
34.5
7.5
7.5
1.5
38.4
38.4
Lampblack or carbon black or stable durable tinting pigments may be
substituted for a portion of the titanium dioxide when a tint or
gray or dull black color is specified. The maximum content shall
not exceed 5 percent by weight of pigment.
Vinyl Resin A shall be a virgin, unprocessed hydroxyl containing
vinyl chloride-acetate copolymer. It shall contain 89.5 to 91.5
percent vinyl chloride, 5.3 to 7.0 percent vinyl alcohol, and 2.0
to 5.5 percent vinyl acetate. The inherent viscosity of the resin
(ASTM 0^1243, Method A) at 20°C shall not be less than 0.5.
***
Vinyl Resin B shall be a virgin, unprocessed carboxyl containing
vinyl chloride-acetate copolymer. It shall contain 85.0 to 87.0
percent vinyl chloride, 12.0 to 14.0 percent vinyl acetate, and
0.5 to 1.0 percent maleic acid. The inherent viscosity of the
resin (ASTM D-1243, Method A) at 20° C shall not be less than 0.48.
Suitable high boiling vinyl resin solvents such as cyclohexanone
may be substituted for a portion of the methyl isobutyl ketone if
the paint is to be applied in hot atmospheric conditions or by
brush.
Source: SSPC, 1973, with permission.
87
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TABLE B-14
CHARACTERISTICS OF WAX PAINT SYSTEMS FOR LINING POTABLE WATER TANKS
Characteristic
Penetration @ 25°C
ASTM D-937
ASTM D-5
Melting Point, °C
ASTM D-127
Solvent Content, %
Phenol, ppm
Hot Applied Wax
30-70
60-77
None
10
Cold Applied Wax
200-250
54-60
20
10
Source: Texaco, Inc.
88
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TABLE B-15
COMPOSITION OF CHLORINATED RUBBER PAINTS
USED IN POTABLE WATER STORAGE TANKS
Ingredients
Chlorinated Rubber Resin -
Type A*
Chlorinated Rubber Resin -
Type B*
Liquid Chlorinated Biphenyl***
Solid Chlorinated Biphenyl ***
Dioctyl Sebacate
Red Lead (97% Grade)
Zinc Yellow
Mica
Indian Red
Talc (Platy, Medium
Consistency)
Organomontmorillonite**
Talc (Medium Consistency)
Rutile Ti02
Lampblack
Toluene
Xylene
Pigment Volume Concentration
Primer
0.0
10.2
5.6
2.7
18.6
3.1
3.1
0.5
7.0
1.3
0.0
0.0
0.0
47.9
0.0
100.0
38.2
% By Weight
Midcoat
0.0
12.1
6.0
3.0
0.0
0.0
0.0
3.9
0.0
0.0
0.4
9.3
2.4
0.2
62.7
0.0
100.0
30.0
Topcoat
15.0
0.0
6.0
3.6
1,5
0.0
0.0
OiO
0.0
0.0
0.0
0.0
17.2
0.2
28.2
28.3
100.0
20.0
*Type B - 67% chlorine and 17-25 at 20% concentration in chlorine at
25 C. (Example: Parlon S-20 for Type B, Parlon S-10 for Type A.)
Example, Bentone 38, registered trade name of National Lead Company.
Source: SSPC, 1973, with permission.
*** Chlorinated Biphenyls are no longer- permitted to be used.
89
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TABLE B-16
ASPHALT BASE OF SEAL COAT FOR CEMENT MORTAR LININGS
Characteristics of Asphalt Base
Specific gravity
Softening point
Penetration @ 25°C
Asphaltene content
Saturated hydrocarbons
Naphthene Aromatics and Polar
Aromatics 59%
Benzo (a) pyrene & other suspect
carcinogens in asphalt base 10 ppb
Nickel 80 ppm
Vanadium 550 ppm
Sodium 25 ppm
Source: The Gregg Co., Inc.
90
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TABLE B-17
EPOXY PRIMER
Composition Pigment - Pure iron oxide with
inhibiting pigments
Vehicle - modified epoxy
Viscosity @ 25°C 80-115 seconds #4 Ford cup
Thinning not to exceed 10% by volume
Recommended Thinner . . . Xylol
Solids by volume .... 39-40%
Solids by weight .... 62+2%
Source: Sterling Division of Reichhold Chemicals, Inc.
91
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APPENDIX C
FDA LIST OF APPROVED POTABLE WATER TANK LININGS
NOTE: This list includes coatings that may be no longer be marketed.
Its presence in this report does not imply that the coatings
listed are acceptable for use in potable water systems at the
present time.
93
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CATEGORY 15: POTABLE WATER TANK LININGS
The following linings for potable water tanks are accepted
solely on the basis that they contain no toxic ingredients which may
be imparted to the water. Such acceptance is predicated on adherence
to manufacturers' instructions for application.
1. Acryloid B-72, Rohm & Hass (Sinclair Refining Company, Marcus
Hook, Pennsylvania) L-1014-57
2. Amercoat #33 (Amercoat Corporation, South Gate, California)
3. Amercoat #33 Gray (Amercoat Corporation, South Gate, California)
4. Amercoat #66 (Amercoat Corporation, Brea, California)
5. Apexuir #3 (Damphey Company, Boston, Massachusetts)
6. Bakelite Resin Aluminum 5504 (Inertol Company, Inc., Newark,
New Jersey)
7. Ballastite #5953 (Farboil Company, Baltimore, Maryland)
8. Ballastite #7340 (Farboil Company, Baltimore, Maryland)
9. Ballastite #7386 (Farboil Company, Baltimore, Maryland)
10. Bisonite "M"
11. Butyl B44 Rubber Compound (F.P.T. Industries Ltd., Portsmouth,
England)
12. Carboline Epoxy 154 F.G. (Carboline Company, St. Louis, Missouri)
13. Cement Wash
14. Coal Tar-epoxy Black Paint (Corps of Engineers Paint & Corrosion
laboratory, Rock Island, Illinois)
15. Collodial Natural Flake Graphite "K-43" (Kograf Corporation,
New York, N.Y.)
16. Devran Coating #207 (Version B) (Devo & Reynolds Company, Inc.,
New York, New York)
95
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17. Durabel Tank Coating #679 (Peroline Company, Inc., New York, New
York)
18. Durabel Primer #8493 (Perolin Company, Inc., New York, New York)
19. Ensign 395 (Ensign Products Company, Cleveland, Ohio)
20. Epon 828 (Shell Chemical Corporation, New York, New York)
21. Epoxy Activator #6330 (Pratt & Lambert, Inc., Buffalo, New York)
22. Epoxy Coating #836-R-10 (Cook Paint & Varnish Company, Kansas
City, Missouri)
23. Epoxy Red Lead Primer #347 (Pratt & Lambert, Inc., Buffalo,
New York)
24. Epoxy Resistant Coating, Black #0483, (Pratt & Lambert, Inc.,
Buffalo, New York)
25. Epoxy Resistant Coating, Silver Gray #71513, (Pratt & Lambert,
Inc., Buffalo, New York)
26. Epoxy Resistant Coating, Dark Gray #71512, (Pratt & Lambert, Inc.,
Buffalo, New York)
27. Epoxylite BC 963, (The Epoxylite Corporation, South El Monte,
California)
28. Epoxylite BC 964, (The Epoxylite Corporation, South El Monte,
California)
29. Epoxylite BC 965, (The Epoxylite Corporation, South El Monte,
California)
30. Epoxylite 203, (The Epoxylite Corporation, South El Monte, Cal-
ifornia)
31. Epoxylite 211, (The Epoxylite Corporation, South El Monte,
California)
32. Eureka Fluid Film, Grade WT (Eureka Chemical Company, San Fran-
cisco, California)
33. Farbertite (Briggs Bituminous Composition Company, Philadelphia,
Pennsylvania)
96
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34. Farbo-Coat #73 (The Farhail Company, Baltimore, Maryland)
35. Farbo-Coat #64 (The Farhail Company, Baltimore, Maryalnd)
36. Fed-Cote (Pioneer Latex & Chemical Company, Inc., Middlesex,
New Jersey)
37. Formula C-200 (Corps of Engineers Paint & Corrosion Laboratory,
Rock Island, Illinois)
38. Formula T2908 (Red Hand Paint Company, New York, New York)
39. Fresh Water Paint No. 1810 (International Paint Co., Inc.,
New York, NY)
40. Gilsonite Asphalt Coating #827 (Detroit Graphite Company, Lyons,
Illinois)
41. HERESITE P-403 (Heresite & Chemical Company, Manitowoc,
Wisconsin)
42. Horsey-Set (Horsey, Robson & Company, Inc., New York, New York)
43. Inertol No. 49 Thick (Inertol Company, Inc., Newark, New Jersey)
44. Intergard Solvent Free Blue 4421 (International Paint Co., New
York, NY)
45. Intergard Solvent Free Reactor 4423 (International Paint Co.,
New York, NY)
46. Intergard Solvent Free White 4424 (International Paint Co., New
York, NY)
47. Jennite J-16 (Maintenance, Inc., Wooster, Ohio)
48. Jennite J-16-R (Maintenance, Inc., Wooster, Ohio)
49. Kata-Pontex Enamel (Intertol Company, Inc., Newark, New Jersey)
50. KOLMETAL (Erajay Maintenance Engineers, Rutherford, New Jersey)
51. Koppers Bitumastic Tank Solution #C-63240-BS-A-1477 (Koppers
Company, Inc., Westfield, New Jersey)
52. Liquid Stainless Steel (Lockrey^Fater Corporation, New York,
New York)
97
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53, Napko Durachlor Fresh Water Tank Enamel 5014 White (Napko Paint
& Varnish Works, Houston, Texas)
54. Napko Fresh Water Tank Enamel #2360 Metallic Brown (Napko Paint
& Varnish Works, Houston, Texas) r
55. Navy Formula #26
56. Navy Formula #102
57. NO-OX-ID "A Special" (Dearborn Chemical Company, Chicago,
Illinois)
58. Orange Phenolic Primer 6261 (Humble Oil & Refining Company,
Houston, Texas)
59. Palmer 7078 Epoxy Coating (Palmer Products, Inc., Worcester
Pennsylvania)
60. Pitt Chem Amide Cured Coal, Tar Epoxy Coating (Pittsburgh Chemical
Co., Pittsburgh, Pennsylvania)
61. Pitt Chem Coal Tar Urethane Coating (Pittsburgh Chemical Co.,
Pittsburgh, PA)
62. Pitt Chem Coating Powder, (Pittsburgh Chemical Co., Pittsburgh,
PA)
63. Pitt Chem Permapipe Compound (Pittsburgh Chemical Co., Pittsburgh,
PA)
64. Pitt Chem Tarset Primer (Pittsburgh Chemical Co., Pittsburgh,
PA)
65. Pitt Chem TARSET Red (Pittsburgh Chemical Co., Pittsburgh, PA)
66. Pitt TARSET Standard- Coal Tar Epoxy Coating (Pittsburgh Chemical
Co., Pittsburgh, PA)
67. Rigortex No. 3305 Enamel Finish (Inertol Company, Inc., Newark,
New Jersey)
68. Rigortex No. 3305 Intermediate (Inertol Company, Inc., Newark,
New Jersey)
69. Rigortex No. 3305 Primer (Inertol Company, Inc., Newark, New
Jersey)
98
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70. Rigortex No. 3313 Enamel Finish (Black & Aluminum Finish only),
Inertol Company, Inc., Newark, New Jersey)
71. Rigortex No. 3313 Primer (Inertol Company, Inc., Newark, New
Jersey)
72. Rigortex No. 3324 Enamel Finish (Black & Aluminum Finishes only)
(Inertol Company, Inc., Newark, New Jersey)
73. Rock-Tar T.O. (Detroit Graphite Company, Lyons, Illinois)
74. Rust-Ban PH 6297 or 6297 (Humble Oil & Refining Company, Houston,
Texas)
75. Rust-Oleum Series 400 to 499 (Rust-Oleum Corporation, Evanston,
Illinois)
76. Rust-Oleum #9323 Aqua Blue (Rust-Oleum Corporation, Evanston,
Illinois)
77. Rust-Oleum #9332 Aqua Green (Rust-Oleum Corporation, Evanston,
Illinois)
78. Rust-Oleum #9334 Green Zinc-Sele (Rust-Oleum Corporation,
Evanston, Illinois)
79 Rust-Oleum #9374 Orange Primer (Rust-Oleum Corporation,
Evanston, Illinois)
80. Rust-Oleum #9384 Light Gray (Rust Oleum Corporation, Evanston,
Illinois)
81. Rust-Oleum #9385 Gray Zinc-Sele (Rust Oleum Corporation, Evanston,
Illinois)
82. Rust-Oleum #9390 White Primer (Rust-Oleum Corporation, Evanston,
Illinois)
83. Rust-Oleum #9392 White (Rust-Oleum Corporation, Evanston, Illinois)
84. Sarva Compound - Sarva Acid Resisting Paint
85. Serviron
86. Sherwin-Williams Coating F52 A A8 (Sherwin-Williams Co., Washington,
D.C.)
87. Socony-Vacuum Product #2305 (Socony-Vacuum Oil Co., Inc., Wash-
ington, D.C.)
99
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88. Special Laykold Binder Formula #510 (American Bitumuls & Asphalt
Company, San Francisco, California)
89. Sure Seal Butyl Rubber Membrane (Carlisle Tire & Rubber Division
of Carlisle Corporation, Carlisle, Penssylvania)
90. Texaco Rustproof Compound H* (Texaco, Inc., New York, New York)
91. Texaco Rustproof Compound L (Texaco, Inc., New York, New York)
92. Tenec #199 (Tnemec Company, Inc., Kansas City, Missouri)
93. Unitite (Acorn Refining Company, Cleveland, Ohio)
94. Valdura #584 Sarva Liquid Black (Martin Marietta Corp., Kankakee,
111.)
95. Valdura #585 Sarva Liquid Red (Martin Marietta Corp., Kankakee,
Illinois)
96. Vinoplast Topcote (Lockrey-Frater Corporation, New York, New
York)
97. Vinyl Primer Red (International Paint Co., Inc., New York,
New York)
98. Vinyl White (International Paint Co., Inc., New York, New York)
99. Zinc Dust Base Paint #2406 (International Paint Co., Inc., New
York, NY)
100. Zinc Dust Primer - Formula #102 (Mil. Spec. 15145)
*Acceptance predicated on use below 125° F.
100
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APPENDIX D
APPLICATION PROCEDURES FOR PIPE AND TANK LININGS
The procedures presented in this Appendix are only a brief
summary of the detailed procedures found In the literature* They
are Included for Information only* Before painting any pipe or
tank, the detailed guides furnished by the paint manufacturer, the
Steel Structures Painting Council, the National Association of
Corrosion Engineers, and/or the American Water Works Association
should be consulted*
101
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D.I Hot Applied Coal Tar Enamel
Linings can be applied in the shop or in the field. Storage
tanks, because of their large size, are usually erected in the field
and lined in place. Pipe sections up to about 10 feet in diameter
can be lined in the shop and, depending on the method of assembly,
may need to be touched up in the field. If the pipe sections are to
be joined by welding, the practical minimum pipe diameter for enamel
lined pipe is 27 inches where only the joints have to be lined in the
field. If mechanical joining methods are used, the entire length of
the pipe can be coated in the shop since the lining at the joined
ends will not be damaged by the heat of a welding operation. The hot
applied coal tar enamel can then be used in pipes as small as 4 inches
in diameter. Because better control can be exercised over shop
applied linings, the quality of shop lining is better. Also, the
cost of applying the lining is lower because it can be applied at a
faster rate. On the other hand, field application has an advantage
in that damage to the lining from handling prior to installation is
avoided.
After cleaning the metal surface by pickling or blast cleaning
(commercial blast cleaning as a minimum), a primer coating Is applied.
Two types of primer are covered in AWWA standard C-203 (1973). One
is a coal tar based primer consisting of an unfilled coal tar
pitch cut back with a coal tar distillate. It is similar to the
cold applied coal tar paint (tasteless and odorless) described In
103
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Table B-2. It can be applied by brushing, roller coating or spraying
and gives a 0.002 inches thick coating covering about 400 square feet
per gallon.
The other primer is a synthetic resin based on chlorinated rub-
ber. It has many advantages over the cold applied coal tar primer
and is now almost universally used as the primer for hot applied coal
tar enamel lining systems. The synthetic resin is a low solids
lacquer-like material applied to a film thickness of about 0.001
inches. Care is required when spraying the primer so that a uniform
sag-free coating of the desired film thickness is obtained. The
enamel may be applied up to 2 weeks after the primer coat is dry.
Five days is specified in the AWWA standard.
If the primer is shop applied to the metal plates that will be
used to construct a tank, it should not be applied to the edges that
will be welded. Field weld seams are to be blast cleaned and primed
after erection. This also applies to the edges of pipes that will be
joined by field welding.
Shop lining of steel pipes with hot coal tar enamel is done by a
spinning process. The properly melted coal tar enamel* is introduced
by a weir or by a trough which is inverted to pour the hot enamel
lengthwise along the revolving pipe. It is important that the enamel
*Care must be used in melting or heating the enamel so as not to coke
the enamel. Too high a temperature, or prolonged heating can
embrittle the enamel and render it less serviceable and more suscept-
ible to damage from handling (Bureau of Reclamation, 1976).
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be at a temperature between 475°F and 500°F in order to obtain a
well-bonded, uniform coating.
The average thickness of the coating should be 0.094 inches. If
the coating is too thick it is more susceptible to cracking in cold
weather and sagging in warm weather and to separation from the steel
substrate.
Large diameter pipes, storage tanks, and pipe fittings are lined
by hand daubing with tamplco fiber daubers. The hand applied lining
is applied in two coats to a total thickness of 0.094 inches. After
application, the lining should be inspected with an electric flaw
detector to locate voids or missed spots which must subsequently be
repaired.
The vapors from the hot applied enamel will condense on cold
surfaces in the tank. Before placing the tank in service, the
surfaces of the tank that have been exposed to condensing vapors
should be thoroughly flushed to avoid contaminating the water
(Steiber, 1978).
D.2 Cold Applied Coal Tar Paint
Cold applied coal tar paint is applied to steel which has been
pickled or subjected to at least a commercial blast cleaning* The
paint can be applied directly to an unprimed surface. If a primer is
used, it should be the same primer as that used for the hot applied
coal tar enamel described above.
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A minimum of two coats of paint are applied by brushing, or
spraying, to a film thickness of .032 to .040 inches. Brushing is
preferred for the first coat. Satisfactory spray application
requires the use of special spraying equipment designed for heavy
bodied materials (Fair, 1956). Each coat of paint must be thoroughly
dry before applying a subsequent coat to avoid entrapment of solvent.
Twenty-four hours is considered a minimum drying time. During cool,
damp weather, several days may be required between coats.
D.3 Cold Applied Tasteless and Odorless Coal Tar Paint
Cold applied coal tar paint that is tasteless and odorless is
also applied to steel which has been pickled or subjected to commer-
cial blast cleaning as a minimum. It is self-priming and applied in
three coats to a total dry film thickness of 0.006 to 0.008 Inches.
D.4 Coal Tar Epoxy
Coal tar epoxy paint is applied to steel which has been subjected
to at least a commercial blast cleaning. The paint is prepared for
application by mixing 1 gallon of liquid epoxy resin with 3.5 gallons
of the component containing the coal tar pitch and curing agents,
fillers and solvent. The two paint components should be mixed vigor-
ously for at least 2 minutes with a power agitator equipped with a
3-inch or longer blade (SSPC, 1973). If it is necessary to thin the
paint for spray application, only xylene should be used. Not more
than 1/2 gallon of xylene should be added to the 4.5 gallon mixture.
The paint should be applied as soon after mixing as practical since
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the mixture reacts chemically and will thicken substantially over a
2-hour period. It is a good practice to mix no more than can be
applied in a 2-hour period.
The temperature of the surface to be painted should be no less
than 50°F during application and for 5 days following. Use during
hot weather when temperatures exceed 90°F is also undesirable as
the pot life of the material is shortened considerably.
The coating is usually applied by spray in two coats to a mini-
mum dry film thickness of 0.016 Inches. The minimum drying time
between coats is 12 hours. The paint develops a hard glaze rela-
tively quickly which can inhibit adhesion of a second coat; there-
fore, a maximum of 72 hours drying time Is suggested under normal
circumstances. During hot weather, the time between coats may have
to be shortened to 24 hours. On external surfaces exposed to sun and
wind, it may be necessary to apply the second coat within 6 hours.
D.5 Coal Tar Urethane Paint
Application procedures for coal tar urethane paints are similar
to those used for coal tar epoxy. For water immersion, a special
primer coat may be required (SSFC, 1973). Urethane paints cure
better than epoxy paints at low temperatures. It has been reported
that urethane coatings have cured at temperatures as low as 2.2°F
(Brown, 1973). Urethane paints also cure faster than epoxy. It is
recommended that 8 to 14 days be allowed before contact with potable
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water because the solvents used with urethane paints are slow to
evaporate (Wallington, 1971).
D.6 Cement Mortar Lining of Pipe
Cement mortar linings are usually shop applied to pipes by a
spinning (centrifugal) lining process. The process consists of
feeding the mortar slurry into the bore of a rapidly rotating pipe so
that the mortar is spread uniformly over the pipe bore by centrifugal
force. After the mortar is in place, the pipe continues to rotate
for about 90 seconds to compact the lining. The pipe is then removed
from the rotating mechanism and inclined slightly (about 10°) to
allow excess water to drain away. A smooth lining of uniform thick-
ness is obtained and a continuous layer of cement mortar is produced
over the pipe bore with minimal sand segregation and a surface
substantially free from a cement-rich layer. Such a layer can form
if spinning continues for too long a time. The pipes are usually
held in the lining shop overnight after lining to protect them from
extremes of temperature and humidity while in the "green" state.
The cement mortar can also be applied by a spray process. In
this process, a centrifugal applicator head, situated at the end of a
lance that is supported on a wheeled carriage, is pushed through the
pipe. The mortar mix is pumped through the lance to the applicator
head which throws the mix onto the pipe surface. The rate at which
the lance is drawn through the pipe controls the thickness of the
lining. The lining can be smoothed by rotating the pipe for about a
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minute or by use of a drag trowel. The spray process is usually used
for lining pipe in the field. Fittings are lined with cement mortar
by hand and trowel. The lining mix is varied slightly depending on
the size of the pipe, and the application process, as shown in Table
D-l. A leaner mix is used in larger pipes to avoid the risk of
shrinkage cracking. A richer mix is required for the spraying
process to improve "flowability." The richer mix tends to give
higher shrinkage contractions than the normal spinning mix (Padley,
1975).
In order to cure properly, the cement mortar lining must remain
moist while curing* The ANSI standard for cement mortar lining of
cast iron and ductile iron pipe suggests applying a bituminous seal
coat material to the moist lining to inhibit moisture loss during
curing (ANSI, 1974). Petroleum derived asphalt based coatings are
commonly used as a seal coat. The components of an asphalt based
seal coat are asphalt, mineral spirits and xylene. A typical asphalt
base is characterized in Appendix B, Table B-16.
In addition to aiding the curing process, the seal coat also
protects the cement mortar from decalcification in soft (calcium
dissolving) waters. Although the decalcification process does not
seriously damage the pipe, the increase in alkalinity of the water
gives the water a flat, unpleasant taste and produces a staining of
aluminum kitchen utensils. It may also affect the quality of products
made with the water (Padley, 1975).
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TABLE D-l
CEMENT MORTAR LINING MIXES
CENTRIFUGAL LINING OF
<_ 200 mm DIAMETER PIPE
parts by weight")
CENTRIFUGAL LINING OF
200 mm DIAMETER PIPE
(parts by weight)
HAND AND TROWEL
LINING OF FITTINGS
(parts by weight)
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The AWWA standard for cement mortar lining of steel pipe does
not include this curing option (AWWA, 1971). In steel pipe, one of
three methods is used: sealing the ends of the pipe; spraying the
lining with water; or alternating applications of steam and water to
the lining (AWWA, 1971).
A cement mortar lining is less sensitive to variations in sub-
strate quality or application procedures than other linings (Padley,
1975). The pipe surfaces must be cleaned to remove loose or other
foreign matter and there should be no projections which may protrude
through the lining (ANSI, 1974; AWWA, 1971). Cement mortar has been
successfully used over existing failed linings where only loose
portions of the failed lining were removed before applying the cement
mortar (Goulding, 1975).
D.7 Epoxy Paint Systems
Epoxy linings can be applied to pipelines in the field or in a
shop. If the pipeline is to be welded, field application after the
pipe is in place and all welding is complete is preferred. This is
because the internal lining will be burned off at the weld joints.
In small pipe it is not practical to repair the lining and in larger
pipelines repair is time-consuming and Impedes construction progress
(Crawshaw, 1975). The surface of the steel must be chemically
cleaned or commercial blast cleaned, leaving an etched surface to
ensure permanent adhesion of the lining (Crawshaw, 1975). The
surface is then neutralized, phosphatized, completely dried and
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immediately coated with epoxy. The epoxy is allowed to dry and
additional coatings are applied until the desired thickness is
obtained. The lining is allowed to cure before being placed into
service. A 0.002 inch zinc silicate base coat can be used instead of
phosphate treatment to inhibit corrosion and improve adhesion of the
epoxy lining. The dry film thickness of the epoxy over the zinc
silicate is 0.006 to 0.008 inches (Cook, 1977).
One method of applying the epoxy to pipe interiors is by forcing
the paint through calibrated orifice openings in pigs in the correct
quantity against the pipewall as the pig is propelled through the
pipe by compressed air. Relatively uniform film thickness and
complete coverage is obtained. A wiper pig is used to smooth the
surface and collect excess epoxy. The epoxy should not be applied if
the temperature of the pipe is less than 40°F (Crawshaw, 1975).
In storage tanks, a typical single component epoxy paint is
applied as a 3-coat system with a minimum dry film thickness of
0.00425 inches. The first or primer coat is an epoxy paint contain-
ing a corrosion-inhibiting pigment such as iron oxide. A typical
primer is characterized in Appendix A. The primer is spray applied
over commercial blast cleaned or pickled steel to a thickness of
0.0015 to 0.002 inches. The remaining coats should be applied to a
dry film thickness of 0.0015 inches each. At least 24 hours of
drying time should be allowed between each coat. The total dry film
thickness must be at least 0.00425 inches or additional coats will
have to be applied.
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The temperature range for applying this epoxy system is 35° to
90°F. The relative humidity should be less than 80 percent. No
problems have occurred when this paint is applied in a thick film
over warm metal surfaces.
The tank should be allowed to dry for at least 5 days at atmos-
pheric temperatures at 20°F or higher.
The two-component epoxy system specified in the AWWA draft pro-
posed standard for painting steel tanks (AWWA, 1977) is applied in 2
or 3 coats to dry film thickness of 0.008 Inches. Although the AWWA
standard considers commercial blast cleaning or pickling to be
adequate surface preparation, paint manufacturers recommend near-
white blast cleaning for the two-component epoxy system (Sterling*
1977; Tnemec, 1977). The prime coat is spray applied to a dry film
thickness of 0.003 inches and additional coats are spray applied to
a total dry film thickness of 0.008 inches. At least 24 hours drying
time at 60°F is recommended to allow for proper curing and adequate
solvent release. Forced ventilation is recommended to accelerate
solvent release and removal from the tank*.
These high-build epoxy system should not be applied at ambient
temperatures below 60°F. The relative humidity must not exceed 85
percent. The coating must be allowed to cure for a 7- to 10-day
period at atmospheric temperatures of 60°F or higher before the
tank is filled with water.
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D.8 Vinyl Paint
For best performance it is generally recommended that near-white
blast cleaning or pickling be used to clean the surface of steel to
be protected with vinyl paint. If a wash coat is used (5-coat
system) it should be brushed or sprayed on to the clear bare steel to
a dry film thickness of 0.0003 to 0.0005 inches. The wash coat has a
pot life of 8 hours and any material remaining after that time should
be discarded. After drying (1/2 to 4 hours), the wash coat should be
covered with a vinyl paint coat.
For systems not utilizing the wash coat*, the prime coat should
be applied to the steel surface immediately after blasting, preferably
by brushing. The remaining coats can be sprayed.
For all vinyl systems, the surface to be painted should be dry
and above 35°F. The paint should be applied to obtain a 0.001 inch
dry film thickness per coat. Air drying for 24 hours between coats
is desired to allow for complete solvent removal. At least 48 hours
drying time should be allowed before immersion. The ambient tempera-
ture should be 45° to 90°F for proper application and curing. The
relative humidity must be less than 80 percent.
D.9 Wax
Wax coatings can be brushed or sprayed on to steel with little or
no preliminary cleaning of the surface. It can be applied over old
*Wash primer is no longer recommended by most manufacturers for fresh
water immersion service (SSPC, 1973).
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rust, paint or rust-proof compound (Texaco, 1973). However, the AWWA
standard for painting tanks (AWWA, 1964) recommends commercial blast
cleaning of new tanks prior to application of the wax. The cold
applied wax may be applied by thoroughly rubbing it onto and into the
clean, dry surface with good, stiff-bristle brushes. Thorough
wetting of the metal surface and displacement of moisture is desired.
The cold applied wax may also be sprayed on using nonatomizing spray
equipment. The wax must be heated to 30°F (or above its melting
point) when spray applied. The wax is applied to a thickness of
0.020 to 0.030 inches and smoothed to eliminate brushmarks and
holidays•
Hot applied wax is applied at a temperature of 30°F (or above
the melting point) with a spray apparatus using fluid pressure
through the nozzle. Prior to application the metal surface must be
dried with a flame applied by a flared torch. After application, the
lining is flashed or flamed by means of a torch to smooth out all
laps and close any pinholes. The thickness of the lining is between
0.030 and 0.060 inches (AWWA, 1964).
D.10 Chlorinated Rubber
Commercial blast cleaning is the minimum degree of cleaning
required for the application of a chlorinated rubber coating.
However, it is recommended that a near-white blast cleaned surface be
prepared for immersion service (White, 1978).
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There are two primers available for use with this system. The
chlorinated rubber primer, as specified by the AWWA, has been shown
to produce better results (Christofferson, 1978). Nevertheless, a
zinc-rich primer is widely recommended (Lombardo, 1978; White, 1978).
The chlorinated rubber primer is applied to a maximum dry film thick-
ness of .002 inches. The zinc rich primer is applied at up to 0.008
inches dry film thickness.
An intermediate coat of chlorinated rubber paint is applied to
a dry film thickness of 0.002 to 0.005 inches after the primer has
dried for at least 30 minutes. This coat can be topcoated after
drying for 2 hours at 60° to 80°F. The topcoat has a dry film thick-
ness of 0.0015 to 0.002 inches. The total system has a thickness of
0.006 inches according to AWWA specifications. Other proprietary
systems can be as thick as 0.0095 inches (White, 1978). Waters
(1978) claims that temperature and humidity conditions are not
critical for application and that the coating can be applied at
temperatures as low as 0°F. This is disputed by Koppers Company
(1978) who states that ice on the surface to be coated can cause
severe bonding problems.
All coats in this system are spray-applied. One of the advan-
tages of using chlorinated rubber is the ease of applying new coats.
Each new application softens the previous coat so that intercoat
adhesion is excellent. Once the system cures, individual coats can
no longer be distinguished.
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D.ll Metallizing Zinc
Sprayed metal zinc is generally applied with a wire-fed gun con-
sisting of an air or electric motor and suitable gears for feeding
the metal wire through an oxygen gas flame. As molten particles tear
away from the wire tip, they assume a spherical shape. The particles
flatten when they strike the surface of the steel. Most of the bond
is due to a mechanical interlock. It is important that a suitable
anchor pattern be developed on the steel surface* This is accomp-
lished by blast cleaning to white metal using one of three types of
grit - salt free angular silica sand or crushed garnet, angular steel
grit, or aluminum oxide as specified in AWWA standard D102-64,
Section 3.8.3. To minimize deterioration in tank surface quality
between sandblasting and metallizing, the metallizing operator can
follow directly behind the sandblasting operator and apply the zinc
coating to a section of the tank as soon as sandblasting of that
section is completed (Warner, 1978). An average zinc thickness of
0.010 inches is applied.
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APPENDIX E
DIRECTIONS FOR DETERMINING THE WATER EXTRACTABLE SUBSTANCES
FROM A POLYMERIC OR RESINOUS WATER CONTACT SURFACE
NOTE: These procedures are currently being revised.
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Convenient size pieces of the polymer or the coating applied to
a suitable noncorrodable substrate should be prepared in a manner
that they can be completely submerged in a container so that each
surface will be in full contact with the extracting medium. The
container should be of such a size that it will hold not less than 10
milliliters of volume of extractant per square inch of surface.
Coating materials should be applied to the substrate at a time that
will allow the extraction procedure to be undertaken at the minimum
specified time of curing.
Prior to undertaking the extractions, the surfaces should be
examined and carefully rinsed with deionized distilled water to
remove any extraneous materials present. A solution of sodium
hypochlorite containing a hundred parts per million of chlorine at pH
10.5 should be prepared using deionized distilled water and heated to
a temperature of 70°F. The sample should be placed in contact with
this solution for not less than 4 hours maintained at this tempera-
ture. The chlorine solution is then discarded and the sample again
rinsed with deionized distilled water.
A sufficient amount of deionized distilled water is heated to a
temperature of 120°F and poured over the samples until completely
covered as before, the container covered with aluminum foil and the
system maintained at 120°F for a period of 48 hours.* The extractant
*Note: Consideration is being given to lowering the test temperature
to 90°F.
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from 120 square inches of the polymer surface is evaporated to about
100 milliliters in a pyrex flask on a hot plate and then transferred
to a clean, tared, platinum dish, flushing the flask three times with
deionized distilled water to remove the last traces of the extractant.
The latter is evaporated to a few milliliters on a low temperature
hot plate and the last of the water is removed by evaporation in an
oven maintained at 212°F. The platinum dish is cooled in a dessicator
for 30 minutes and the residue weighed to the nearest tenth of a
milligram. The amount of extractives is calculated as milligrams of
extractive per square inch of surface. If this value turns out to be
less than 0.5 milligrams per square inch, no further experimental
work need be done. If the level Is higher than that, the analyst may
choose to make a determination of the chloroform soluble extractives
described on page 464 of the Code of Federal Regulations, Title 21,
Food and Drugs, Part loo to 199, revised as of April 1, 1977. (This
text is printed below.)
Schedule of tests to be conducted.
1. Follow protocol above. 3. Delete hypochlorite treatment.
2. Follow protocol above. 4. Delete hypochlorite treatment.
Chloroform-Soluble Extractives Residue
Add 50 milliliters of chloroform (freshly distilled reagent
grade or a grade having an established consistently low blank) to
the dried and weighed residue in the platinum dish. Warm carefully,
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and filter through Whatman No. Al filter paper in a Pyrex funnel,
collecting the filtrate in a clean, tared platinum dish. Repeat
the chloroform extraction, washing the filter paper with this second
portion of chloroform. Add this filtrate to the original filtrate
and evaporate the total down to a few milliliters on a low tempera-
ture hotplate. The last few milliliters should be evaporated in an
oven maintained at 212°F. Cool the platinum dish in a desiccator
for 30 minutes and weigh to the nearest 0.1 milligram to get the
chloroform-soluble extractives residue, e'. This is substituted
in equation E-l below:
Milligrams extractives per square inch - — =Q (E-l)
s
where s is the surface area of the coating, square inches and e'-
milligrams extractives per sample tested. The value of "e" must
not exceed 0.5 milligrams per square inch.
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