United States
Environmental Pr-t«ction
A^ancy
Control Technology
C*ntw
rienarch Triangle Park NC 27711
EPA-600/2-90-019
May 1990
Assessment of VOC Emissions from
Fiberglass Boat Manufacturing
control ^technology center
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development. U.S. Environmental
Protection Agency, have been grouped into nine series. These nine broad cate-
gories were established to facilitate further development and application of en-
vironmental technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The nine series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
6. Scientific and Technical Assessment Reports (STAR)
7. Interagency Energy-Environment Research and Development
8. “Speciar Reports
9. Miscellaneous Reports
This report has been assigned to the ENVIRONMENTAL PROTECTION TECH-
NOLOGY series. This series describes research performed to develop and dem-
onstrate instrumentation, equipment, and methodology to repair or prevent en-
vironmental degradation from point and non-point sources of pollution. This work
provides the new or improved technology required for the control and treatment
of pollution sources to meet environmental quality standards.
EPA REVIEW NOTICE
This report has been reviewed by the U.S. Environmental Protection Agency, and
approved for publication. Approval does not signify that the contents necessarily
reflect the views and policy of the Agency, nor does mention of trade names or
commercial products constitute endorsement or recommendation for use.
This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.
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EPA-600/2-90-019
May 1990
ASSESSMENT OF VOC EMISSIONS FROM
FIBERGLASS BOAT MANUFACTURING
CONTROL TECHNOLOGY CENTER
Sponsored by:
Emission Standards and Engineering Division
Office of Air Quality Planning and Standards
U.S. Environmental Protection Agency
Research Triangle Park, North Carolina 27711
Air and Energy Engineering Research Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Research Triangle Park, North Carolina 27711
Center for Environmental Research Information
Office of Research and Development
U. S. Environmental Protection Agency
Cincinnati, Ohio 45268
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PREFACE
The Control Technology Center (CTC) was established by the U.S.
Environmental Protection Agency’s (EPA) Office of Research and Development
(ORD) and Office of Air Quality Planning and Standards (OAQPS) to provide
technical assistance to state and local air pollution control agencies. Three
levels of assistance can be accessed through the CTC. First, a CTC HOTLINE
has been established to provide telephone assistance on matters relating to
air pollution control technology. Second, more in-depth engineering
assistance can be provided when appropriate. Third, the CTC can provide
technical guidance through publication of technical guidance documents,
development of personal computer software, and presentation of workshops on
control technology matters.
The technical guidance projects, such as this one, focus on topics of
national or regional interest that are identified through contact with state
and local agencies. In this case, the CTC became interested in assessing the
magnitude of VOC emissions from fiberglass boat manufacturing and possible
emission control techniques available to reduce these emissions.
This document describes the fiberglass boat manufacturing industry and
the sources of VOC emissions during the manufacturing process. Emissions
control methods such as material substitution, process changes, and add-on
control equipment are discussed. Eoth demonstrated control technologies and
evolving control technologies are presented.
ii
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EPA- 600/2-90-019
May 1990
ASSESSMENT OF VOC EMISSIONS
FROM
FIBERGLASS BOAT MANUFACTURING
by
M. B. Stockton and I. R. Kuo
Radian Corporation
P. 0. Box 13000
Research Triangle Park, North Carolina 27709
EPA Contract No. 68-02-4286
Work Assigr ment 48
EPA Project Officer: Charles H. Darvin
Industrial Processes Branch
Air Toxics Research Division
Air and Energy Engineering Research Laboratory
U. S. Environmental Protection Agency
Research Triangle Park, North Carolina 27711
U’
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ABSTRACT
This report presents art assessment of VOC emissions from fiberglass boat
manufacturing. First, a description of the industry structure is presented.
This includes estimates of the number of facilities, their size, and
geographic distribution. The fiberglass boat manufacturing process is then
described along with the sources and types of VOC emissions. Model plants
representative of typical facilities are also described. Estimates of VOC
emissions are presented on a per plant and on a national basis. VOC emissions
from this industry consist mainly of styrene emission from gel coating and
lamination, and acetone or other solvent emissions from clean-up activities.
Finally, an evaluation of potential VOC control technologies is made for this
industry. This evaluation includes a discussion of technical feasibility.
Limited cost data are also provided.
As used in this report, “fiberglass” means fibrous glass or
fiberglassreinforced plastic. The term does not necessarily mean
Fiberglas, trademark of Owens/Corning Fiberglas Corporation, Toledo, Ohio.
iv
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CONTENTS
Pa g e
Preface . ii
Abstract iv
Figures vi
Tables
Conversion of English Units to SI Units ix
Acknowledgement
1. Introduction 1
2. Conclusions and Recommendations 2
Conclusions 2
Recommendations 5
3. Industry Structure 7
Industry size 7
Major manufacturers and geographic distribution 7
Economic viability of industry 11
Major trade associations 16
4. Fiberglass Boat Production 18
Process overview 18
Laminates and lamination methods 22
Alternative molding methods 27
Cleanup 29
5. Process Emissions 30
Emission sources 30
VOC emission rates from boat manufacturing 36
6. Emission Control Techniques 41
Process changes 41
Add-on controls 56
References 82
Glossary 89
V
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FIGURES
Number P ge
1 Geographic distribution of fiberglass boat manufacturing
facilities 13
2 Fiberglass boat production process 19
3 Representative plant layout 21
4 Absorption system with stripping tower and solvent recycle 62
5 Cross-section schematic of the Blitz Rol1er 66
6 Chempro Scrubber with catenary grids 67
7 Styrex’ system bench top pilot unit 69
8 Results from Styrex” system bench top tests 72
9 Chemtact chemical scrubber using atomizing nozzle and
sodium hypochiorite solution 74
10 Carbon adsorber system process flow diagram 78
vi
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TABLES
umber Page
1 Number of establishments in the boat building and
repairing industry 8
2 Major fiberglass boat manufacturers 9
(Based on number of total individual models produced)
3 Major fiberglass boat manufacturers 10
(Based on minimum total tangible assets)
4 Geographic distribution of the in4us try by
number of facilities 12
5 Value shipments for product classes 14
6 Financial parameters for boat building and repairing versus
commercial and industrial dry cleaning 15
7 Trade associations 17
8 Typical components of resins 23
9 Examples of initiators used with polyester resin 25
10 Fiberglass reinforcements for boat hulls 26
11 Emission factors for uncontrolled polyester resin
product fabrication processes 32
12 Factors affecting styrene emissions from lamination 32
13 Model plants - small boats 37
14 Model plants - large boats 38
15 National VOC emissions from fiberglass boat manufacturing 40
16 Comparison of resins which reduce styrene emissions 43
17 Comparison of properties of laminates made with
low styrene resins versus conventional resins 46
18 Comparison of methods to reduce VOC emissions from
clean-up operations 51
vii
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TABLES
Number Page
19 Exhaust air VOC concentrations for three fiberglass
reinforced plastics industries 57
20 Si i ury of runs performed in the bench-top evaluation
of the Styrex’ system 70
viii
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CONVERSION OF ENGLISH UNITS TO SI UNITS
English Unit Multiply by To Obtain
Tons 0.907 Metric tons
Pounds 0.454 Kilograms
feet 0.304 m
cftn 28.314 l/tnin
ix
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ACKNOWLEDGEMENTS
The authors acknowledge the contributions of Radian Corporation’s Keith
arnett, Lynn Rhodes, Reese Howle, and John Stelling. The support provided by
Radian’s Lee Davis, Jeff Elliott, and Chris Eagley is also recognized.
x
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SECTION 1
INTRODUCTION
The purpose of this study was to conduct a survey of the fiberglass
marine craft production industry to define the nature and scope of volatile
organic compound (VOC) emissions from this source. The study includes total
industry VOC emissions and the geographic distribution of the industry.
Emissions from different industry segments, specific processes identified in
the industry, industry structure (production rate, employment), and economic
data (such as cash flows) were also determined. This study also includes an
evaluation of potential VOC control options. Although this report is directed
primarily toward boat manufacturing, the resulting technologies identified may
also be applicable to other molded fiberglass operations. Phase 1 of this
study was conducted in the spring of 1989. Phase 2, which included additional
information gathering on emission controls, was conducted during September and
October 1989.
Typically, the modern marine pleasure craft is manufactured using a
molded fiberglass structure. Previous studies indicate that over 22,000 tons
of VOC per year are emitted from fiberglass boat manufacturing operations in
the United States. Significant concentrations of boat manufacturing
facilities exist in the Great Lakes area, along the coastal areas of the
country (i.e., California, Texas, Florida and South Carolina), and near
recreational rivers and lakes, such as those located in Tennessee. As a
result,. fiberglass boat manufacturing may potentially impact local air
quality.
1
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SECTION 2
CONCLUSIONS AND RECOMMENDATIONS
The major findings from this study are presented below. The conclusions
can be categorized in four groups: 1) industry characterization, 2) process
emissions, 3) emission reductions through process or material changes, and 4)
emission reductions through add-on controls. In general, substitution of
lower VOC-containing materials is the most promising method of reducing VOC
emissions. Add-on controls for reducing VOC emissions have not generally been
demonstrated for this industry. A combination of the control techniques
presented below may be used for even greater emission reduction.
CONCLUSIONS
Industry Characterization:
- - The distribution of fiberglass boat manufacturing facilities is
not limited to coastal States. Boat manufacturing facilities
are located in 36 States.
- - There appears to be significant geographical concentrations of
boat manufacturing facilities in the following coastal areas:
Puget Sound, Washington; Miami and Tampa Bay, Florida; and Los
Angeles, California. There is also a significant concentration
of manufacturing facilities in central Tennessee. Boat
manufacturing facilities are fairly evenly distributed between
inland and coastal areas in coastal States.
- - The majority of national emissions are from medium size plants
employing between 50 and 100 workers and producing boats less
than 30 feet long.
2
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• Process Emissions
- - Total National VOC emissions from fiberglass boat manufacturing
are estimated to be 20,150 tons per year. Approximately
64 percent of these emissions are styrene; resulting from gel
coating and lamination, the remainder is acetone or some other
solvent used during clean-up.
-. The major emission sources are exhausts from gel coat spray
booths, room exhausts from the lamination area, and evaporation
of acetone or other solvents during clean-up.
- - Fiberglass boat manufacturing companies typically induce
ventilation to meet the 100 ppmv OSHA styrene limit established
for these operations. As a result, exhaust streams from
individual .plants are typically characterized by high flow
rates and low VOC concentrations.
Emission reductions through process or material changes:
- - Water/detergent emulsions can be used to replace approximately
50 percent of the solvent used for clean-up. This would be
expected to reduce clean-up emissions by approximately
50 percent. These cleaners are successfully being used
commercially in boat plants for resin clean-up and their use
has been required as a permit restriction to reduce VOC
emissions from fiberglass boat plants in some recent Best
Available Control Technology (BACT) decisions. However, based
on industry experience, these detergent emulsions appear to be
inadequate for gel coat clean-up or cured resin.
- - Alternate cleaning compounds containing dibasic esters (DRE)
are currently being tested at a number of fiberglass boat
plants. These cleaners show the potential to replace acetone
completely for resin and gel coat clean-up. Due to the much
lower vapor pressure of dibasic esters, these substitutes can
provide dramatic VOC emission reductions.
- - Low styrene resins are currently available and being used in
the industry. Styrene emissions can be reduced by
approximately 14 percent using a 35 percent styrene by weight
resin. There are limits to the use of low styrene resins in
the fiberglass boat manufacturing industry, however very few
boat companies have been able to reduce styrene content below
35 percent by weight without sacrificing some of the structural
integrity of the boat.
- - While vapor-suppressed resins show the greatest potential for
styrene emission reductions, they are currently not being used
by the fiberglass boat manufacturing industry due to the high
cost of the resin and problems in secondary bonding which
3
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reduces product strength. Potential styrene emission
reductions range from 20 to 35 percent. In order for these
resins to be widely applied, problems with bonding between
successive layers of resin will need to be resolved. Resin
manufacturers are seeking solutions to this problem.
-- Work practice controls, such as limiting the amount of clean-
up solvent issued to employees performing lamination, and the
use of gloves and covered containers, can reduce VOC emissions
by an estimated 22 percent. Additional VOC reductions can be
achieved through reclamation and recycle of waste acetone.
- - Properly operated air-assisted airless spray guns have the
potential to reduce emissions from application of gel coat and
resin by 50 and 33 percent, respectively. This could reduce
total styrene emissions by approximately 9 percent.
Emission reductions through Add-on controls:
- - Of the add-on controls evaluated in this study, incineration is
the only demonstrated and readily available technology for
controlling VOC emissions from fiberglass manufacturing
facilities. Although incineration is not being used in a boat
manufacturing facility to date, it has been installed as a
means of VOC control in a fiberglass tub and shower facility.
Incineration can reduce VOC emissions by 90 percent or more;
however, the cost per ton of VOC removed can be expensive
(e.g., $15,000/ton) due to the high exhaust flow rates and low
VOC concentrations characteristic of this industry.
• - - There are no known applications of carbon adsorption to the
fiberglass boat manufacturing industry. Use of carbon
adsorption in this industry may be restricted due to the
potential for styrene to polymerize on the carbon and
deactivate the bed, and due to the vast difference in the
capacity for carbon to absorb styrene versus acetone. The
adsorptive capacity of styrene is 30 percent, while the
capacity for acetone is only 1 to 2 percent, thus making the
removal of acetone the limiting design criteria.
- - There are no known applications of chemical scrubbers to the
fiberglass boat manufacturing , industry. However, there are two
systems, Cheatact and Styrex that could theoretically be used
for removing scyrene from exhaust air. Both systems require
further testing and analysis to demonstrate commercial
viability for this industry.
4
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RECOt NENDATIONS
The following recommendations are made for additional study of the
control technologies described in this report.
Material Substitutions
It appears, based on current information, that the control technology
offering the greatest potential for VOC emission reductions at low costs are
the substitution of lower VOC-containing materials. These include vapor-
suppressed resins, low styrene resins, water-based emulsions for clean-up, and
dibasic ester (DBE) compounds for clean-up. Further study to determine the
applicability and limitations of using these materials for fiberglass boat
manufacturing is warranted. The following recommendations for additional
investigation should be undertaken to define their performance and economic
viability for future application to this industry:
• Perform reformulation and laboratory testing of vapor-suppressed
resins to determine if addition of adhesion promoters can
effectively eliminate secondary bonding problems and improve
structural performance for boat fabrication.
• Perform additional product strength testing of laboratory samples
and/or prototype boats made with low styrene resins to determine the
effect on product quality of reducing the styrene content in resins.
• Contact additional formulators of water-based emulsion cleaners and
with boat manufacturers using these cleaners to clarify cleaning
performance, overall costs, worker safety issues, and waste disposal
issues.
• Investigate the feasibility of reformulating water-based emulsions
to make them suitable cleaners for gel coat clean-up.
• Investigate the applicability of dibasic ester compounds for clean-
up in boat manufacturing plants and to quantify VOC emissions
associated with the use of these cleaners. Two boat plants were
identified during this study that have recently starting using DBE
cleaners in their production. The performance, overall costs,
worker safety issues, and waste disposal issues faced by these
plants should be evaluated further.
5
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Add-on Controls
There are currently three control devices that have been reported to have
potential for controlling VOC and styrene emissions from fiberglass boat
manufacturing facilities. However, they have not been commercially
demonstrated in the U.S. They are the Styrex scrubber, the ChemtactlW
scrubber, and the polyade polymer system. Numerous technical issues still
require resolution before these technologies can be considered demonstrated
for fiberglass emissions control. Technical issues and data required for the
styrex and chemtect technologies are outlined below.
Styrex
• - Develop equilibrium data and perform a theoretical design
evaluation to assess the limitations of these system;
- - Determine the efficiency of the system at low inlet
concentrations (i.e., 1-80 ppmv VOC);
- - Determine the feasibility of continuous regeneration and
recycle of the Styrex using a bench top or pilot unit;
- - Perform a full economic analysis of a commercial unit including
waste disposal costs.
. Chemtact
- - Determine through laboratory testing, if sodium hypochlorite
oxidizes acetone and styrene and if so, what are the potential
reaction products and by-products;
- - Evaluate the efficiency of the sodium hypochiorite oxidation
process through examination of the liquid effluent and outlet
air ducts of existing installations; and at low inlet
concentrations of styrene.
The Po1yade technology has been applied in Europe. However, it still
remains to be applied in the United States fiberglass boat industry. However,
evaluations are still required to define the technical and economic viability
of the system in the U.S. industrial envirorunent.
6
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SECTION 3
INDUSTRY STRUCTURE
This section contains industry distribution and economic information for
the total boat building and repair industry, and for the fiberglass boat
production segment of this industry.
INDUSTRY SIZE
The fiberglass reinforced plastic (FRP) boat manufacturing industry
represents a segment of SIC code 3732, Boat Building and Repairing.
Currently, 1,822 facilities comprise the boat building and repair industry as
a whole, although only 214 of these establishments employ 50 or more people.
The total estimated number of employees is approximately 47,000. The
fiberglass boat manufacturing segment of the industry is composed of 695 small
boat facilities producing boats larger than 30 feet in length. Table 1 shows
the size distribution (the number of facilities and employees per employment
size class) for the total boat building and repair industry in 1985 and for
the fiberglass boat manufacturing segment alone in 1987.
MAJOR MANUFACTURERS AND GEOGRAPHIC DISTRIBUTION
Although most fiberglass boat manufacturers produce only six to seven
individual models, a few large establishments produce more. The list of major
fiberglass boat manufacturers presented in Table 2 indicates the facilities
which produce 14 or more individual models. Another means of determining
major boat manufacturers is to identify those with the highest total tangible
assets (Table 3). Only 3 manufacturers (Welicraft, Glasply, and Sea Ray) are
found on both lists.
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TAILI 1. NUWIER 0 ? ESTAILISHHENT$ IN THE bAT bUILDING MID UPAIEING INDUSTRY
Istabi L.h..nt
TotsI Industry,
19S5
?1b.r ls.s lost
Plants,
L.r .
boats°
Sasit
E 1o y..nt
Number of
Numb.r
of
Nu.b.t
of
Number of
Number of
lumbar
of
lIsa Cl i ..
E.tsbLI.hmsnts
Employ...
Estsblt .hm.nts
Employ...
£.t.blt.hm.nts
Employ...
1 to 4 533 1,3 56
453 350 2,450
S to 9 333 2,263
10 to 19 242 3,251
20 to 49 196 5,595 120 $760 313 25,830
30 to 99 94 6,461
100 to 249 55 13,253
230 to 499 26 9,075 10 2, 150 30 4,920
500 to 999 9
1,000 or Nor. 0 0
TOTAL 1,122 47,419 195 12,063 695 33,200
9.fer.nc. 1.
bR.f.r.nc. 2.
5 bosts over 30 f..t In 1.nitb.
dIGit. I... than 30 f..t In 1.n th.
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TABLE 2. MAJOR FIBERGLASS BOAT MANUFACTURERSa
(Based on number of total individual models produced)
Name Number of Models Location
Welicraft 22 Sarasota, FL
Chaparral 21 Nashville, CA
Chris Craft 21 Brandenton, FL
Sun Runner 18 Spokane, WA
Baja 17 Bucyrus, OH
Century 17 Panama City, FL
Checkmate 17 Bucyrus, OH
Sea Ray 17 Knoxville, TN
Star Craft 16 Goshen, IN
Sylvan 16 New Paris, IN
Marlin 15 White City, OR
Regal 15 Orlando, FL
Sawyer 15 Oscada, MI
Clasply 15 Marysville, WA
Glastron 14 New Braunfels, TX
Larson 14 Little Falls,
Thompson 14 St. Charles, MI
VIP 14 Vivian, LA
‘References 3-6.
9
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TABLE 3. MAJOR FIBERG lASS BOAT MANUFACTURERS ’ 1 ’
(Based on minimum total tangible assets)
Name Assets (in millions) Location
Bertram 50 Miami, FL
Helms 50 Irino, SC
Trojan 50 Lancaster, PA
Welicraft 25 Sarasota, FL
Galaxy 10 Columbia, SC
Glasply 10 Marysville, WA
Sea Ray 10 Knoxville, TN
Carver 5 Pulaski, WI
Cruisers 5 Oconto, WI
Glass Master 5 Lexington, SC
Hinkley 5 Southwest Harbor, ME
Irwin S Clearwater, FL
Morgan 5 Largo, MA
O’Day (Banga-Ponta) 5 Fall River, MA
Magnum 5 N. Miami Beach, FL
Ranger 5 Flippin, AR
Reference 7.
bSome large companies do not appear in this table because they did not report
their assets in published literature or because they are part of a much larger
corporation, (e.g.. Bayliner, Grady White, Hatteras Yachts).
10
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The geographic distribution of the industry by number of facilities in
each State is shown in Table 4. Of the 48 continental United States, 14 do
not contain any fiberglass boat manufacturing establishments according to the
references used.
As shown in Table 4, the following States have 10 or more boat
manufacturing facilities: California, Florida, Illinois, Indiana, Michigan,
North Carolina, South Carolina, Tennessee, Texas, and Washington. For the
States listed above, the geographic distribution by State is presented in
Figure 1. Points which represent more than one establishment in a given city
are assigned a numerical value.
ECONOMIC VIABILITY OF INDUSTRY
Total value shipments for the entire BoatBuilding SIC presented in
Table 5, have shown a 13.6 percent average increase since 1982, increasing
from 2 billion dollars in 1982 to 3.6 billion dollars in 1986. While the
manufacturing of less popular types of boats, such as canoes, rowboats, and
“boats not elsewhere classified” show unstable growth patterns, value
shipments for outboard motorboats, and inboard-outdrive boats, which together
make up the majority of the industry, show steady increases from 1982 to 1986.
Value shipments for Boat Repairs were excluded in order to represent the boat
production industry alone.
Most boat manufacturing facilities tend to have a small number of
employees (less than 50). Also, boat manufacturing is characterized as a low
technology labor intensive industry. Data on the financial status of the
industry is only available for boat manufacturing in general. It is assumed
that since fiberglass boat manufacturing makes up such a large percentage of
all boat building, the data shown are representative. Major financial
parameters for both commercial and industrial dry cleaning facilities,
respectively, are also shown in Table 6 for comparison. Dry cleaning
facilities were selected for this comparison because they are also a low
11
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TABLE 4. GEOGRAPHIC DISTRIBUTION OF THE INDUSTRY BY NUMBER OF FACILITIESa
Alabama 4 Montana -
Alaska - Nebraska 1
Arizona 4 Nevada -
Arb aii as 9 New Hampshire -
California 23 New Jersey 5
Colorada - New Mexico
Connecticut 3 New York 3
Delaware - North Carolina 10
Florida 77 North Dakota -
Georgia 8 Ohio 5
Hawaii Oklahoma 4
Idaho - Oregon 4
Illinois 12 Pennsylvania 2
Indiana 13 Rhode Island 7
Iowa 1 South Carolina 14
Kansas 4 South Dakota -
Kentucky 3 Tennessee 40
Louisiana 9 Texas 21
Maine 7 Utah 1
Maryland 8 Vermont -
Massachusetts 9 Virginia 1
Michigan 14 Washington 11
Minnesota 8 West Virginia -
Mississippi 3 Wisconsin 6
Missouri 9 Wyoming -
£Reference 8.
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FIgure 1. GeographIc DIstrIbution of Fiberglass Boat ManufacturIng Facilities
Plants for States wfth More Than Ten Facilities
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TABLE 5. VALUE SHIPMENTS FOR PRODUCT CLASSES (1982-1986) £
Industry
and
Product
Value of P
(in mill
roduct
ions of
Shipmentsb
do11ars
1986
1985
1984
1983
1982
Class Code Description A
B
C
D
E
37322 Outboard Motorboats 759.3 650.5 657.1 449.1 345.0
37323 Inboard Motorboats 1022.1 779.6 748.8 580.8 522.3
37324 Inboard/Outdrive Boats 1156.2 912.3 691.6 530.6 459.9
37327 Boats n.e.c. 309.2 388.2 524.3 403.0 368.8
37320 Boat Building n.s.k. 391.2 330.2 399.5 302.3 293.2
3732 Total - Boat Building 3638.0 3060.8 3021.3 2265.8 1989.2
Reference 9.
b 13 6 percent. average annual increase
14
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TABLE 6. PINANCIAL PARAMETERS FOR BOAT BUILDING AND REPAIRING VERSUS CO 04ERCIAL AND INDUSTRIAL DRY CLEANING a
SIC 3732
Boat BuiLding, Repairing
(No Breakdown)
)9 7 (269 Es bLi.h..ny)
UQ° HEDC LQ
SIC 7216
Dry Cleaning, P1.? U Rug
(No Breakdown)
19 7 (619 Esçpbiisiflç 1 L
UQ° N ED ° LQ
SIC 7218
Industrial Launderer
(110 Br.akdown)
1957 (96 Estabitstwaent I)
UQU I4EDC LQ°
Boat
SIC 3132
Building. Repairing
(No Breakdown)
Dry
1957
SIC 1216
Cleaning. P1.? U Rug
(No Ireakdown)
(619 EstablIshment.)
SIC 7218
Industrial Launderer
(No Breakdown)
1957 (96 Est.bLi.hn4nSa)
1987
(269 Establishments)
B
1
1
S
I
Total Current Asset.
233780
60.1
54,360
34.6
396,061
50.0
Total Assets
417,401
100.0
137,109
100.0
779,641
100.0
Total Current Liabilities
142,401
100.0
33,970
22.9
240,911
30.9
1st Worth
200.770
48.1
02,452
32.3
359,824
30.0
Total Liabilities and Net
Net Sales
Worth
417,401
956,739
100.0
100.0
151.109
309,063
100.0
100.0
779.648
1,400,000
100.0
100.0
Gross Profit
216,498
28.9
173.073
56.3
591,000
42.7
Net Profit after Tax
33,399
3.1
22.310
7.2
91.000
6.3
Working Capital
111,029
18,382
153,130
I .- ’
U’
Ratios
So1venc
Quick Ratio (TImes)
1.3
0.7
0,3
Current Ratio (Ti.es)
Current Liabilities to Net Worth (percent)
3.8
18.1
1.9
56.4
1.2
148.8
4.1
8.9
1.7
26.2
0.7
73.5
3.4
23.3
1.9
51.1
1.0
106.3
Total Liabilities to Net Worth (percent)
29.6
74.1
242.1
17.0
37.9
138.3
37.1
82.4
182.3
Profitability
Return on Sal.a (percent)
8.8
3.9
0.7
16.4
3.1
1 .0
10.1
4.8
2.1
Return on Assets (perc.nt)
14.8
8.2
1.3
25.4
1.1
0.8
13.1
7.5
3.3
.
Return on Net Worth (percent)
33.5
15.5
3.5
53.6
16.4
2.1
30.8
15.5
10.0
aReference 10.
t ’UQ — upper qnart lie (752)
CHED — medIan (101)
d 1 Q — lower q. .rtile (252)
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technology industry and a source that has been considered for regulation.
Also, both dry cleaning and boat building industries are made up of relatively
small facilities. Parameter definitions can be found in Appendix A.
MAJOR TRADE ASSOCIATIONS
Table 7 lists the names and addresses of the trade associations
associated with fiberglass boat iuanufacturing.
16
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TABLE 7. TRADE ASSOCIATIONS
Fiberglass Fabrication Association
732 Eighth Street S.E.
Suite 200
Washington, D.C. 20003
Society of the Plastics Industry, Coniposites Institute
355 Lexington Avenue
New York, NY 10017
American Boat Builders and Repairers Association
715 Boylston Street
Boston, MA 02116
National Marine Manufacturers Association
401 N. Michigan Avenue
chicago, IL 60611
17
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SECTION 4
FIBERGLASS BOAT PRODUCTION
This section describes the fiberglass reinforced plastic boat production
process.
PROCESS OVERVIEW
Figure 2 presents an overview of the fiberglass boat production process.
The most common production method is open contact molding.” The discussion
in this section will be limited to this method. However, other molding
methods are discussed in a later section.
The open contact molding method consists of laying up plies of resin
impregnated fiberglass reinforcement on an open mold. The layers are built up
to the desired thickness, then allowed to cure at room or elevated
temperature. A male mold is convex leaving a smooth inner surface while a
female mold is concave leaving a smooth outer surface. Although it is easier
to lay up reinforcements on a male mold, a female mold is generally preferred
since a smooth outer surface is more desirable for boat hulls and decks. 12
As shown in Figure 2, the inner surface of the female mold is usually
coated with a wax which ensures easy removal of the finished product from the
mold after cure. Next, gel coat, a layer of resin without any reinforcing
material, is sprayed into the empty mold to a precise thickness. Gel coat
consists of unsaturated polyester resin, catalyst, and pigments, together
forming the smooth outer surface of the final product. Gel coat spray systems
often consist of separate resin and catalyst sources and an airless spray gun
(similar to the type used in paint spraying) which mixes the two chemical
18
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....ldlng Room - Muw mia.y rwuuu.
I.— I
Hull and Dock Fabrication
• apply resin Remove
• lay fiberglass rein Vorcem.nt from Mold
• wet out
• sand
oId Gel
Coot • assemble boot
with Wax t hhh10 !d13 SF?r Y Booth
• Intall carpet and
accessories
Small Parts Spray Booth
Small Parts Fabrication
Remove
• spray on from Mold
• wet out
Figure 2. FIberglass Boat Production Process
-------
ingredients as they exit the gun. An initial clear layer of gel. coat
containing a UV inhibitor protects colors from wear and potential degradation
from exposure to ultraviolet light. After the gel coat application, the mold
is typically left to cure overnight. The first laminate of resin and
fiberglass is applied using one of several lamination methods. The laminate
can be applied by hand brushing or by spray-up operations. For a quality
finish, the first layer of resin is applied and allowed to cure. Additional
layers of laminate are then applied in succession to the desired thickness.
Structural reinforcements, such as wood, plastic, and metal can be added
for extra strength. Plywood bonded with fiberglass may be added to the
transom of the boat to concentrate strength in this highly stressed area. 13
Some manufacturers tie this into the stringer system constructed of kiln dried
boards extending the length of the hull. Sometimes as many as six stringers
are used to preserve the shape of the boat over time. ’ The entire system is
then encapsulated with resin and fiberglass for additional strength. To
comply with Coast Guard regulations governing certain flotation
specifications, hollow spaces between the stringers and along the sides of the
hull are filled with closed-cell urethane foam.
Figure 3 shows a representative process layout. As previously mentioned,
gel coat application is usually performed in a ventilated spraybooth.
However, for small facilities it is sometimes performed in the open molding
area. The next portion of the production process takes place in the molding
room. In some facilities, this room is completely open; in others, it may
have a series of enclosures. The molding room is also ventilated to reduce
styrene vapor exposure. This ventilation may be as simple as opening the doors
and using roof exhaust fans, or could consist of push-pull ventilation systems
with floor sweeps and other intakes designed to capture the heavy styrene
vapors as efficiently as possible.’ 5 ’ 7
Regardless of the specific design, one common characteristic is that the
ventilation systems are typically designed to move large amounts of air to
keep styrene levels in the work place below a 100 ppmv permissible exposure
20
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Moidin Areo
This areq may be completely open or
consist 01 0 series oV enclosUres
Assembly Room
Gel oa
Sprayuooth
I - a
Gel Coal
SproyBooth
molI Parts
SproyBoolh
FIgure 3. RepresentatIve Plant Layout
-------
limit (PEL) as required by Occupational Safety and Health Administration
(OSHA) regulations. 18 Small parts may also be produced in the molding area,
usually in a spray booth.
After the parts are removed from the mold they are taken to the assembly
room where they are sanded and assembled. In addition, carpet and accessories
areS installed to produce the finished product.
After the lamination process is complete, the parts are taken to the
assembly room. This room may be separated from the molding area. Separating
this area serves two purposes. First, it avoids exposing workers in the
assembly area to styrene vapors generated during lamination. Second, it
reduces the amount of air volume the lamination area ventilation system is
required to move. This can be especially important in cold climates where the
makeup air must be heated in order to maintain the temperature in the molding
area within the range necessary for proper resin curing.
LAMINATES AND LAMINATION METHODS
A laminate consists of layers of fiberglass reinforcing material bonded
together with resin. It is called fiberglass reinforced plastic (FRP), or
simply fiberglass.
Although epoxy, phenolic, and melamine resins are available, polyester
resins are used almost exclusively in fiberglass boat manufacturing because of
their cost advantage and versatility. 19 Table 8 presents the typical
components of polyester resins. Most polyester resins used in the boat
industry contain styrene monomer as the linking agent. The typical styrene
content ranges from 40 to 50 percent for resins and 35 to 42 percent for gel
coat. 20
22
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TABLE 8. TYPICAL COMPONENTS OF RESINS
To Form the Unsaturated Polyester
Unsaturated Acids Saturated Acids Polvfunctional Alcohols
Maleic anhydride Phthalic anhydride Propylene glycol
Fumaric acid Isophthalic acid Ethylene glycol
Adipic acid Diethylene glycol
Terephthalic acid Dipropylene glycol
Neopentyl glycol
Pentaerythritol
Monomers
Styrene
Methyl methacrylate
Vinyl toluene
Vinyl acetate
Diallyl phthalate
Acrylamide
2-ethyl hexylacrylate
Reference 21.
23
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In order to be used in the fabrication of products, the liquid resin must
be mixed with an initiator to promote polymerization. Initiator
concentrations generally range from 1 to 2 percent by original weight of
resin. Within certain limits, the higher the catalyst concentration, the
faster the cross-linking reaction proceeds. Common initiators are organic
peroxides, typically methyl ethyl ketone. peroxide or benzoyl peroxide.
Table 9 presents a variety of initiators commercially available. Resins may
contain inhibitors to avoid self curing during resin storage, and promoters to
allow polymerization to occur at lower temperatures.
Table 10 shows the different types of fiberglass reinforcing material
used in boat manufacturing. The part being formed and the type of molding
method determines the type of reinforcement used. All the reinforcements
shown may be used in the contact molding method except preforms. The other
molding methods shown are discussed in the next section.
There are three methods used to produce laminates in open contact
molding: machine lay-up, hand lay-up, and spray lay-up. Machine lay-up
involves the simultaneous mechanical application of fiberglass reinforcement
material and resin and is generally reserved for large hull boats, such as
sailboats. For such large surfaces, machine lay-up provides more even
application of the layers than hand or spray lay-up. The laminate may require
hand rolling to remove air pockets or other imperfections.
In the hand lay-up method, a thin coat of resin is brushed or sprayed on
the tacky surface of the gel coat. Fiberglass reinforcement (usually mat or
woven roving) is placed into the mold, over the wet resin. Additional resin
is usually applied over the fiberglass to complete the avet outs of laminate.
The laminate is then rolled by hand to remove air pockets and other
imperfections. Generally, the ratio of resin to glass is 60 to 40 by
weight. 23
After the first layer of resin gels, alternate layers of resin and
reinforcement materials are added. For each successive layer, the resin is
24
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TABLE 9. EXAMPLES OF INITIATORS USED WITH POLYESTER RESINZ
Chemical Name Form
Zenzoyl Peroxide Wet nu, Paste, Suspension
Methyl Ethyl Ketone Peroxide Liquid
25-Dimethyl-2,5-bis Liquid
(2- Ethyl -hexanoyl - peroxy) Hexane
t-Amy Peroxy 2-Ethyl Hexanoate Solution
t-Butyl Peroxy 2-Ethyl Hexanoate Liquid/Solution
t-Butyl Peroxy Maleic Acid Paste
l,l-bis(t-Butyl Peroxy) Cyclohexane Powder
Cyclic Peroxyketal Liquid
Di Peroxydicarbonate Wet Granules, Powder
Lauroyl Peroxide Flakes, Wet Granules, Paste,
Emulsion, Powder
t Reference 24.
25
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TABLE 10. FT rntu&cS RZI1lP CE TS F BOAT 8Uu.sa
Typeb
Construction
Thickness
Weight
Application
Mo Id ing
Method
Ro rtnas
Unidirectional
Greater m bsr of strand.e in
wrap Strands placed parallel
to each otb.r in ama
direction only.
La required
Additional strength
in on.. direction.
Usually placed
loc*Lly, i.e.
longitudinally at
keel and deck to aid.
Contact. Bag,
Resin Transfer
Uoven
connections.
Stiff.ners.
Roving formed in kea’,y plain
weave, slightly heavier in
the wrap direction,
. 025—. 043
14-27 eel sq 74
24-27 Os most
popular
Primary reinforcement
for hull end deck.
Contact, Bag
ouped Fibers
Mat
—— — chopped fibers bonded
together with resin binder
or .. h .ic ,ally needled
together.
.030—.080
314 — 3 oslsq ft
1-1/2 and 2 os
most popular
Primary reinforcement
for hull and deck.
Reinforcement for
bonded joints. Water
barrier in cloth or
woven roving
Laminates. if igh bulk
for building
thickness.
Contact. Bag.
Resin Transfer
Preform.
Randc. chopped fibers
deposited over a preform
screen and banded together
with resin binder.
As required
Primary reinforcement
for hull and deck.
Furnishings and hull
coopanenta • i.e.,
seats, bunks, hatch
cowers, etc.
Resin Transfer
Continuous
Continuous strands randomly
As required
Primary reinforcement
Fibera and
Strand.
chopped and mixed with resin
using * chopper g .
Fillers added as required
for molding c ounds.
for hull and deck,
Sigh bulk for
building thickness
and filling soaj.l
void spaces. Small
parts, i.e., deck
cleats, arm rests.
trims, etc.
tea in
deposited
s in.zitaneous ly
on nol d,
Contact. Bag,
R esin Transfer
CLoth
Weave
Plain square open weave with
slightly greater nrmber ef
strand.. in warp (lengthwise)
direction,
.008-. 022
7.3 - 19 os sq
74 10 oz most
popular
Primary reth.forcemsnt
for bull and deck.
Surface coat
reinforcement. Local
areas for additional
strength in two
directions.
Contact. Bag
Unidirectional
Cromfoot satin weave with
greater nrmber of strands in
warp.
Additional strength
in on. direction.
Usually placed
locally, i.e..
longitudinally at
keel and deck to side
Connections.
Contact, Bag,
Resin Transfer
C mbinat tons
Cloth end Mat
Fiberglass mat needled or
mechanically stitched to
cloth,
2 os sq ft mat
with 10 os sq 74
cloth most
popular
Primary reinforcement
for hull and deck.
Contact, Bag
Roving. and
Nat
Fiberglass mat needled to
roving,
2 os sq ft mat
with 24—27 os sq
yd woven roving
most popular
Primary reinforcement
for hull and deck.
Contact, Bag
aRalerence 23.
ball r.Lnforc nts to have a stL size or finish for mexi wet strength retention.
26
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applied by a resin gun or brushed on by hand and each layer is wetted out to
assure complete contact between the resin and reinforcement. Each layer is
rolled out to remove air bubbles which could ultimately reduce product
strength. The lamination procedure is repeated until the desired thickness is
achieved. Ordinarily, stress areas get more layers of laminate.
Catalyst injection resin guns are the most common type of resin guns used
in hand lay-up. These mix accelerated resin (resin containing a promoter) and
a catalyst (to initiate curing) in the proper proportion inside the spray gun
head and then spray the mixture through a single spray nozzle. 26
Alternatively, catalyst can be injected at full strength directly into the
resin.
Spray lay-up is the most coon method of small parts production and is
an alternative to hand lay-up for hull and deck fabrication. The spray method
employs a chopper gun which is capable of simultaneously depositing chopped
strand fiberglass and catalyzed resin on the mold. Rollers are used, as in
hand lay-up, to remove entrapped air.
The laminates in spray lay-up generally have a lower glass to resin ratio
than laminates produced in hand lay-up. 27 Because the strength properties are
directly proportional to the glass to resin ratio, spray lay-up processes
sometimes yield a product with a lower strength for the same amount of glass.
This is generally compensated by using more glass and/or additional
reinforcements. Hand lay-up is more time consuming; so a common practice is
to combine the two methods, using spray lay-up more for those parts of the
boat that do not need much strength and for small parts.
ALTERNATIVE MOLDING METHODS
There are a number of alternative closed molding methods which can be
used in manufacturing fiberglass products. Two of these which have been
experimented within the fiberglass boat manufacturing industry are resin
transfer molding and bag molding. Since there are no exposed resin surfaces
27
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in these processes, styrene emissions from the resin are greatly reduced.
More of the styrene is retained in the mixture and added to the polymer as it
cures, instead of volatilizing out of the reactive mixture as it does in open
molding methods.
Resin Transfer Molding
In the resin transfer molding (RTM) process, fiberglass reinforcement
consisting of continuous or chopped strand glass fiber mats is placed between
halves of a mold. After the mold is closed, catalyzed resin is injected into
the mold and allowed to cure. The mold is then opened and the finished part
removed. Sandwiches of polyurethane foam and polyester resin may also be made
this way.
Resin transfer molding processes have been used to manufacture large
fiberglass products such as automobile hoods and satellite dishes and small
boat parts such as seats, hatch covers, and bait boxes. 2529 They have not,
however, been used on a production basis in the U.S. to make large, complex
boat parts such as decks and hulls. The major technical difficulty in using
the process for these parts is that resin void spaces may occur, thus,
rendering the part unusable. A highly skilled labor force is required for RTM
to be successful.
The capital cost of resin transfer molding equipment is high, and since
boat manufacturers change models frequently, the costs of replacing models
would be high. 3 ° A manufacturer in South Carolina unsuccessfully attempted to
produced 18-20 foot boat deck and hulls using resin transfer molding. The
result was a ruined mold.
Bag Molding
Bag molding uses a bag or flexible membrane to apply vacuum or pressure
during the molding operation and is most often combined with the use of an
autoclave. 3 ’ First, fiberglass reinforcement (laminate) is layed up by hand
28
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and/or spray techniques. Vacuum bag molding applies pressure against the lay-
up by drawing a vacuum under a cellophane, vinyl or nylon bag which covers the
laminate. Pressure bagmolding forces the bag against the laminate using
compressed air or steam. When the bagged assembly is placed in an autoclave
and heated under pressure, the product is given a higher density and allows
use of a higher fiberglass to resin ratio. 32
CLEANUP
Cleanup of hands, tools, and spray guns is a very important part of the
production of fiberglass boats. Tools such as brushes, rollers, and squeegies
are typically cleaned with a solvent after applying resin. Also, spray guns
must be flushed with a solvent after each use and thoroughly cleaned daily.
This cleaning prevents resin from curing on the tools and guns and making them
unusable. In addition, periodic hand cleaning is also necessary for employee
comfort. While employees are encouraged to wear gloves when handling resin,
they do not always wear them for the entire shift.
The cleaning solvent most commonly used is acetone. Although,
alternative ketones, which are less volatile, such as methyl ethyl ketone are
occasionally used. The following discussion presents typical acetone usage
practices; however, these practices would be similar for other cleaning
solvents. Acetone is usually available for each employee in containers at
their work station. Also, internal mix resin guns have a clean acetone feed
line to flush the internal parts after each use. Acetone for hand cleaning
must be relatively clean to avoid hand irritation, therefore, a method is
generally adopted in which clean acetone is first *.tsed for hand cleaning.
When the acetone becomes too contaminated for hand cleaning, it is used for
tool cleaning until it is no longer effective for cleaning tools. Then the
dirty acetone is transferred to a container for soaking the resin gun between
applications. Finally, when the acetone becomes too contaminated for any
further use, it is transferred to a solvent recovery or disposal area. Each
employee usually has his own set of hand and tool cleaning containers in the
molding room and spray gun containers are available for each spray gun. The
containers used may be open top or covered or self closing lids.
29
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SECTION 5
PROCESS EMISSIONS
This section discusses the sources of VOC emissions from the fiberglass
boat production process. Estimates of emission rates are provided for typical
plants and on a national basis.
EMISSION SOURCES
There are four areas in the fiberglass boat production process where VOC
may be emitted to the atmosphere. These are resin storage, the production
area, the assembly area, and waste disposal.
Resin Storage
Most facilities purchase resin in bulk and store the resin outdoors in a
temperature controlled tank. The resin is often transferred to 55 gallon
drums for use in spray systems. 33 If purchased in bulk, some volatilization
of styrene occurs during storage and transfer. No data are available to
quantify these emissions; however, emissions can be estimated using equations
for storage of organic liquids presented in EPA’s AP-42. 34 Typically,
emissions from this source are relatively small in comparison to lamination,
gel coating, and clean-up emissions.
Lamination Area
There are two sources of emissions in the lamination area. The first is
styrene lost during gel coat and resin application and from resin surfaces
during curing. No appreciable emissions of other components of the resin
30
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occur due to their low concentration and/or low volatility. The second source
of emissions is solvents (usually- acetone) used for cleanup of hands, tools,
molds, and spraying equipment.
S tyrene Emissions - -
Styrene emissions occur during the lamination of the deck, hull, and
small parts due to evaporation from the resin or gel coat overspray and
vaporization froii the applied resin or gel coat before polymerization occurs.
Both of these sources of styrene emissions are discussed below.
As previously mentioned, gel coat is always applied by spraying, whereas
the resin can be applied by either spraying or brushing. When spraying the
resin or gel coat, approximately 10 percent of the styrene is lost in
overspray. If the resin is brushed on, only one percent of the styrene is
lost during application. The overspray is made up of small particles;
therefore, there is more surface area for styrene evaporation. Because of
this, it would be expected that total styrene emissions from spraying would be
greater than those from brush application. This is true, although, not all of
the styrene in overspray is lost because overspray also polymerizes. An
additional eight percent is lost during curing.”
Styrene emissions also occur during the curing of the resin or gel coat.
It is estimated that about eight percent of the styrene monomer in the applied
resin or gel coat evaporates before polymerization is complete. 36
Table 11 presents emission factors for uncontrolled polyester resin
product fabrication. The ranges represent the sensitivity of emission to
process parameters. Table 11 also shows that the overall emission factor for
spray lay-up is higher than that for hand lay-up. This is due to the
volatilization of styrene from overspray. Table 12 presents a list of the
parameters which affect emissions. Increases in any of these factors will
increase emissions.
31
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TABLE 11. EMISSION FACTORS FOR UNCONTROU-P 1)
POLYESTER RESIN PRODUCT FABRICATION PROCESSES
Emission Factor, lb styrene emitter perb
100 lb of stvrerte used
Processes Resin Gel Coat
Hand lay-up 5 - 10 26 - 35
Spray lay-up 9 - 13 26 - 35
Closed Molding 1 - 3 N/A
aThe ranges represent the variability of processes and sensitivity of
emissions to process parameters.
bAp42 factors.
TABLE 12. FACTORS AFFECTING STYRENE EMISSIONS FRON LAMINATIONS
Factors Affect on Emissions
Resin Temperatures Emissions increase as temperature rises
Air Temperatures Emissions increase as temperature rises
Spray Gun Pressure/Equipment Greater pressure increases the
Atomization atomization which increases the oversprav
Air Velocity in Lamination Area Greater air flow may increase evaporation
resulting in increased emissions and
decreased concentration
Mold Surface Area Greater surface area allows more
vaporization in terms of total mass
Resin/Gel Coat Styrene Content Increased emissions from increased
styrene monomer content
‘Reference 37.
32
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Acetone Emissions- -
Cleaning solvent emissions can account for over 36 percent of the total
plant VOC emi-ssions. 38 Acetone is the primary cleaning solvent used in the
industry. As discussed earlier, tool and spray gun cleaning is usually
required after applying each batch of resin. Also, employees must clean their
hands periodically. When hands, tools, and spray guns are removed from the
acetone, a good deal of liquid is carried out. This liquid readily vaporizes
due to the high vapor pressure of acetone and the large surface area per
volume of acetone. Additionally, spray guns are normally flushed with acetone
after each resin application. When spray guns are flushed, some of the
atomized acetone vaporizes. In addition to emissions that occur during
cleaning operations, acetone also evaporates from any uncovered acetone
containers in the molding room.
The major factors affecting emissions are the number of lamination
employees, use of covers on acetone containers, use of hand protection,
employee work habits, and resin gel time (i.e., application/cleaning cycle).
The number of lamination employees directly affects total acetone emissions
since each employee must clean his hands, tools, and spray gun (if used).
Also, conmion practice is for each employee to have his own set of acetone
containers which increases the surface area available for acetone evaporation.
Containers with self-closing lids can be used to reduce evaporation between
cleanups.
The use of hand protection reduces the number of times the employees must
clean their hands. The two types of hand protection available are gloves and
barrier creams. Usually employees must clean their hands after every resin
application (every 20 to 30 minutes). The use of gloves can reduce the number
of cleanups to as low as four times daily. 39
Employee work habits can reduce emissions by reducing the amount of resin
which must be removed from hands and arms. Some employees only get a minimal
amount of resin on their hands and body while other employees may get
33
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considerably more on themselves. Employee work habits are mainly influenced
by initial training and supervision. 40 Another factor which can affect the
amount of resin which employees get on their hands and arms is the complexity
of the mold. The more complex the mold the more difficult it is for employees
to keep clean.
The gel time of the resin affects emissions because it determines the
number of times that hands, tools, and spray guns must be cleaned in a given
period of time. Shorter gel times mean more frequent resin applications and
cleanings. Resin gel times can vary from 10 to 30 minutes. However, most
resin gel times are about 15 minutes.’ 1 If hand protection is used, resin gel
time should not affect the frequency of hand cleanup as much as when no hand
protection is used.
Other factors which affect acetone emissions are the vapor space above
the liquid level of acetone in the containers, air velocity across the
containers, and room temperature. Increasing any of these factors will
increase acetone evaporation. These factors are generally determined by the
amount of acetone issued per employee, room air ventilation required for
worker safety, and temperature required for resin curing. The amount of
acetone issued can be reduced if gloves are used to reduce hand cleanup and
covered containers are used to reduce acetone evaporation. Issuing only a
specified amount of acetone to each lamination employee per day for cleanup
reinforces good work habits and contributes to efficient acetone use.
Reducing the room air ventilation is not feasible to reduce evaporation
because this would expose employees to higher concentrations of styrene
vapors. The temperature required for proper resin curing is determined by the
resin manufacturer and cannot be easily changed.
The resin application method (spray gun versus brush application) is not
one of the controlling factors affecting acetone emissions for the following
reasons:
All resin application methods require use of hand tools, such as
rollers and squeegies, and hand contact with the resin.
34
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Brushes are generally used to smooth out resin applied with a resin
gun. Brushes used for resin application rather than for simple
smoothing may require more thorough cleaning, however, the amount of
acetone needed for thorough brush cleaning and resin gun cleaning is
not appreciably different.
Other Pollutants- -
There are other pollutants which may be found in the lamination area.
These include components of the polyurethane foams used for buoyancy and
chemicals used to clean the molds after use. However, the contribution of
these pollutants is very small compared to styrene and acetone.
Assembly Area
The major source of emissions in the assembly area is evaporation of
solvent from glues used in carpet application. The specific amount of
emissions are very site-specific but are usually small compared to styrene
emissions. Clues typically contain l,l,l-trichloroethane (TCA) or a mixture
of TCA and Stoddard solvent, a petroleum distillate used in dry cleaning.
Though TCA is not considered a VOC, it is considered a toxic air pollutant.
Emissions may also include solvents from paints, but these emissions are not
considered to be significant since paint is only used for touch up at the end
of the manufacturing process.
Waste Disposal
The major source of emissions from waste disposal is evaporation of used
acetone from cleanup. Approximately 40 percent of the acetone used in cleanup
is recovered as waste. 42 Previous practice was to allow the acetone in the
waste to evaporate on-site and dispose of the solids. However, many
facilities now reclaim the acetone on-site using batch stills, or ship the
waste to a recycler for acetone reclamation.
35
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VOC EMISSION RATES FROM EOAT MANUFACTURING
This section presents VOC emission estimates on a plant and national
level. Total VOC emissions at any particular boat manufacturing facility will
vary significantly based on the facility size, number, and type of boats
produced. However, the emission estimates presented here can provide some
guidelines on emissions as a function of plant sales and number of employees.
Model Plants
Tables 13 and 14 present data for six model plants. These models are
based on economic models developed as part of a study performed for the
Society of the Plastics Industry (SPI). 43 Table 13 presents data for three
sizes of plants producing small boats (<30 feet). Table 14 presents data for
plants producing large boats (>30 feet).
The estimates for annual sales, number of employees, and plant exhaust
flow rates were taken directly from the economic models. The resin use was
estimated based on total 1987 industry use of polyester resin provided by SPI,
the number of each model plant, and resin cost per plant from the economic
study. Gel coat use is assumed to be one seventh of resin use.” Emissions
of styrene are calculated based on the emission factors shown in Table 11
assuming a 50/50 split of resin use between hand lay-up versus spray lay-up.
Acetone emissions are assumed to be 36 percent of total plant VOC emissions.
Also shown are calculated average VOC concentrations in the plant
exhausts. These average concentrations were calculated based on 2,000 hours
per year of plant operation and annual VOC emissions. The concentrations
shown are very low compared to other VOC sources currently being controlled or
considered for control. This is to be expected due to the requirement to
maintain low styrene vapor concentrations in the work place.
The plant exhaust flow rates shown for the model plants were developed
based on a potential regulatory requirement to reduce styrene exposure to
36
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TABLE 13. MODEL PLANTS - SMALL BOATS (<30 FEET)
Plant Size
Smallh
Medium”
Large”
Annual Sales, $/yr’
385,000
8
,500,000
23,750,000
Total Number of Employees’
7
82
164
Raw Materials use, lb/yr
Resinb
45,800
902,300
1,790,400
Gel Coatc
6,540
128,900
255,800
Acetoned
2,360
46,530
92,350
Emissions, lb/yr
Styrenee
2,520
49,650
98,520
Acetone t
1,420
27,920
55,410
Total VOC
3,940
77,570
153,930
Total Plant’
69,750
124,650
303,300
Exhaust Flow, acfm
Average Exhaust VOC
2
24
20
concentration, ppm
aData taken directly from Reference 45.
bCalculated based on estimated national 1987 resin use in the marine
manufacturing industry from Reference 46, and the total number of model plants
and resin cost per plant from Reference 47.
cAssumes a resin to gel coat ratio of 7/1.
dCalculated based on the assumption that 60 percent of the acetone used is
emitted.
eRased on the emission factors in Table 10, typical resin and gel coat
contents from Section 3, and assuming a 50/50 ratio of hand lay-up to spray
lay-up.
Assumes acetone emissions are 36 percent of total VOC emissions.
Does not include emissions from resin storage or glues. These emissions are
assumed to be negligible compared to other sources.
“For those more familiar with metric units refer to metric conversion table page
ix in front of report.
37
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TABLE 14. MODEL PLANTS - LARGE BOATS (>30 FEET)
Plant Size
Small l
Mediumhh
Large
Annual Sales, $/yr ’
385,000
8
,500,000
48,000,000
Total Number of Employees’
7
73
285
Raw Materials use, lb/yr
Resinb
37,200
664,500
3,222,700
Gel Coatc
5,300
94,900
460,400
Acetoned
1,920
34,270
166,230
Emissions, lb/yr
Scyrene’
Acetond
2,050
1,420
36,560
20,560
177,330
99,740
Total VOC 9
3,200
57,120
277,070
Total Plant’
89,250
309,750
1,239,000
Exhaust Flow, acfm
Average Exhaust VOC
1
7
9
concentration, ppm
‘Data taken directly from Reference 48.
tCalculated based on estimated national 1987 resin use in the marine
manufacturing industry from Reference 49, and the total number of model plants
and resin cost per plant from Reference 50.
CMsumes a resin to gel coat ratio of 7/1.
dCalculated based on the assumption that 60 percent of the acetone used is
emitted.
‘Eased on the emission factors in Table 10, typical resin and gel coat
contents from Section 3, and assuming a 50/50 ratio of hand lay-up to spray
lay - up.
t Assumes acetone emissions are 36 percent of total VOC emissions.
toes not include emissions from resin storage or glues. These emissions are
assumed to be negligible compared to other sources.
hFot those more familiar with metric units refer to metric conversion table page
ix in front of report.
38
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50 ppmv. In the most recent rulemaking, OSHA has exempted the fiberglass boat
manufacturing industry from using engineering and work practice controls
(e.g., ventilation systems, process enclosure, or use of suppressed styrene
resins) to meet the new 50 ppmv standard due to the difficulty and. cost
involved. 51 However, the plant exhaust flow rates and concentrations shown
are still believed to be typical for this industry.
No emissions are shown for disposal of spent acetone. In most cases
waste acetone is either recycled using a batch still or sent off-site for
reclamation, minimizing the amount emitted from disposal.
National Emissions
National VOC emissions from boat manufacturing are shown in Table 15.
These estimates were derived from the number of plants in each size category
and emissions per plant. Small plants make up 47 percent of the total
population but only 4 percent of the total emissions. Medium size plants make
up 49 percent of the facilities and 78 percent of the total emissions.
The geographic distribution of boat manufacturing facilities and,
therefore, emissions were previously shown in Figure 1 for the States having
more than ten facilities. A high concentration of boat manufacturing
facilities occurs in Florida, near Miami and Tampa Bay, in Las Angeles,
California, and in central Tennessee.
39
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TABLE 15. NATIONAL VOC EMISSIONS FROM FIBERGLASS BOAT MANUFACTURING
Number of
P lants
VOC
p
Emissions
er Plant
TPY
VOC Emissions
per Plant
Category, TPYb
Small Boats
Small Plants
350
2.0
700
Medium Plants
315
38.8
12,220
Large Plants
30
77.0
2,310
Larze Boats
Small Plants
65
1.6
100
Medium Plants
120
28.6
3,430
Large Plants
10
138.6
1,390
TOTAL
890
N/A
20,150
aReference 52.
See metric conversion table page ix.
40
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SECTION 6
EMISSION CONTROL TECHNIQUES
This chapter discusses emission control techniques which have the
potential to reduce VOC emissions from fiberglass boat manufacturing. This
includes both demonstrated control techniques and techniques which have not
been demonstrated, but which could potentially be used. These control
technologies are divided into two general categories. The first are process
changes designed to reduce the release of pollutants into the air. These
include improved work practices and raw material substitution. The second is
add-on controls. The discussion of add-on controls includes both demonstrated
control technologies and concepts which have not been fully demonstrated. In
the case of undemonstrated technologies, the key technical uncertainties are
identified and discussed.
PROCESS CHANGES
This section discusses changes in the boat production process which can
potentially be used to reduce the atmospheric releases of VOC. In addition to
reducing emissions, these types of controls offer the added benefit of
reducing worker exposure to acetone and styrene. The discussion is divided
into two sections: process controls for styrene, and process controls for
acetone.
Process Controls for Stvrene Emissions
Four methods were identified for reducing styrene emissions through
process changes. These are: 1) using high transfer efficiency spray guns; 2)
reducing the styrene content of the resin; 3) substituting styrene monomer in
41
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the resin with a less volatile monomer, such as p-methyl styrene; and 4) using
a resin containing a vapor suppressant. High transfer efficiency spray guns
are applicable to both resin and gel coat application. However, the use of
substitute resins will not affect emissions attributable to the gel coat. A
comparison of the three different types of reins which can be used in place of
conventional resins to reduce styrene emissions is presented in Table 16.
Each of these methods is described in further detail below.
High Transfer Efficiency Spray Guns- -
As discussed in Sections 3 and 4, airless spray guns can be used to apply
both gel coat and resin. Airless spray guns mix the resin or gel coat and
catalyst at the spray gun tip. Gel coat is almost always applied with a spray
gun, while resin can be applied to the fiberglass reinforcing materials with
either spray guns or brushes.
Air Assisted Containment (AAC) airless spray guns use an air stream to
contain the mixed resin and catalyst. This air stream reduces overspray
which makes application more efficient, thus reducing styrene emissions. In
one test, it was reported that the average transfer efficiency for an AAC
spray gun spraying gel coat was 90 percent, compared to an average transfer
efficiency of 81 percent for conventional airless spray guns tested under the
same conditions. In tests spraying resin, the reported transfer
efficiencies were 96 percent for the AAC gun versus 94 percent for the airless
spray gun. Comparing these transfer efficiencies would imply that AAC spray
guns would reduce styrene emissions due to overspray by 42 percent for gel
coat application and 33 percent for spray up resin application. For the model
plants presented in Section 5, this technique provides an overall reduction of
nine percent in total plant styrene emissions. It should be noted that the
transfer efficiency for an airless spray gun is highly dependent upon operator
proficiency and may vary from the values reported in this study.
Detailed costs for an air assisted airless spray system were not
developed as part of this study. One manufacturer stated that reducing
42
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TABLE 16. COMPARISON OF RESINS WHICH REDUCE STYRENE EMI SS IONS
Vapor
Low Styrene
Resins
Low VP
Monomer
Suppressed
Resins
Potential 14 % 16% (Styrene 20 - 35 %
Emission emissions may
Reductions be replaced
with other VOC
emissions.)
Working More viscous Similar to Requires extra
Properties than conven- conventional step in manu-
tional resins, resins. facturing
difficult to process to
apply even prepare each
layers. surface between
layers.
Strength May create Similar to Poor secondary
Characteristics weaker laminate conventional bonding between
of L.aminate structure due resins, layers creates
to air weak laminate
entrapment. structure.
Costs Similar to Two times the Resin cost is
conventional cost of conven- 5-10% more than
resins. tional resin, conventional
resin, plus
increased labor
costs to pre-
pare laminate
surface between
layers.
Currently Many plants are Many plants A few plants
Demonstrated able to use currently using this for
resins down to testing resins small boats
—38% styrene. with low VP which do not
Very few are monomer. require high
able to use 35% strength char-
styrene content acteristics.
resins.
43
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overspray results in material savings, and therefore reduces operating costs
compared to conventional spray gun systems.” The actual costs versus
materials savings and emissions reductions will likely be very site-specific.
Low Styrene Resins- -
The styrene content of conventional resins used in the fiberglass boat
manufacturing industry typically ranges from 40 to 50 percent with an average
of 43 percent. Resin manufacturers have been working to meet requests from
boat manufacturers for lower styrene content resins, which also maintain high
mechanical performance.
On March 6, 1987, the South Coast Air Quality Management District
(SCAQMD) adopted a rule requiring that the styrene monomer content of
polyester resins be limited to 35 percent or below unless some other form of
emissions control is used (SCAQMD, Rule 1162). This rule has driven the resin
manufacturing industry to develop resins with lover styrene contents. For
many fiberglass lay-up operations these low styrene resins can be substituted
for conventional resins with little or no change in proc-ess operations or
final product quality. There are currently a number of “low styrene resins”
on the market with styrene monomer content as low as 35 percent. However,
some formulations advertised as low styrene resins are actually mixed monomer
resins comprised of styrene and other organic monomers such as methyl
methacrylate. The total monomer content may still be 40 to 50 percent, thus
potentially offsetting the styrene emission reduction with other VOC
emissions.
y reducing the total monomer content in the resins, emissions can be
reduced. For example, reducing the resin styrene monomer content from
43 percent to 35 percent would reduce styrene emissions from resin application
and curing by approximately 19 percent based on the emission factors presented
in AP-42. For the model plants described in Section 5, this would reduce
total plant styrene emissions by 14 percent and total plant VOC emissions by
approximately 9 percent.
44
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The cost of low styrene resins is approximately the same as conventional
resins. 37
There are limitations on the use of low styrerte resins for fiberglass
boat manufacturing. 58 Low styrene resins are more viscous than conventional
resins, particularly at lover temperatures. The high viscosity makes the low
styrene resins harder to work with and application of a smooth, even layer of
resin in the lamination process is dependent on the skill level of the
operator. Spray-up operations, in which the resin and fiberglass layers are
applied to the mold with spray and chopper guns, respectively, are
particularly affected by resin viscosity. Application of uneven layers
results in varying curing. If a second layer is applied before the first
layer is evenly cured then air entrapment or bubbles can occur which reduces
the strength of the laminate structure. Fiberglass boats typically have 4-6
layers of laminate consisting of layers of chopped glass and roving depending
on the boat size and performance specifications. Producing boats with weaker
laminate structures could result in serious product liability issues,
particularly for high performance speed boats. Consequently, the boat
manufacturing industry has been cautious to substitute low styrene resins in
their production. Table 17 includes a comparison of typical properties of
resins and laminates made with 35 percent styrene monomer resins and
42 percent styrene monomer resins.
A number of boat plants have reduced the styrene content in their resins
to 38-40 percent styrene with satisfactory results. 59 Some boat plants are
using two different content resins: low styrene (35-36 percent) resins for
manufacturing boat decks and small parts such as seats and bait boxes, and
conventional resins (40-45 percent styrene) for boat hulls which require
superior strength characteristics.
The date for boat plants in the SCAQM district to comply with Rule 1162
was July 1, 1988. Very few boat manufacturers have been able to successfully
comply with this rule by reducing the styrene content in their resins to
35 percent. The effect of this rule has been for fiberglass boat
45
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TABLE 17. COMPARISON OF PROPERTIES OF LAMINATES MADE WITH
LOW STYRENE RESINS VERSUS CONVENTIONAL RESINS’
Property
35 Percent Styrene
Content Resins ’
42 Percent Styrene
Content Resinc
Viscosity (Brookfield #2
@
20
rpm)
750 ± 150 cps
600 ± 100 cps
Barcol Hardness (934-1)
37 ± 2
40 ± 5
Flexural Strength (psi)
10,000 ± 1,000
13,500 ± 1,000
Flexural Modulus (psi)
560,000 ± 20,000
500,000 ± 20,000
Tensile Strength (psi)
7,000 ± 1,000
8,000 ± 1,000
Percent Elongation @ Break
1.0 ± 0.2 percent
1.2 ± 0.3 percent
‘Typical properties were extracted directly from Technical Data Sheets for
each product provided by the supplier.
bAltek’ 80-600 I.E Series Resin manufactured by Alpha Resins Corporation.
cAltek’ 526-750 Resin manufactured by Alpha Resins Corporation.
46
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manufacturers to experiment with a combination of material changes, improved
work practices, and additional controls. A number of boat plants have shut
down in the area and relocated to other areas outside the SCAQM district.
Low Vapor Pressure Monomer Resins- -
Styrene monomer can sometimes be replaced by a monomer that has a lower
vapor pressure, such as p-methyl styrene. The main advantage of p-methyl
styrene is that its vapor pressure is two to three times lower than that of
styrene, depending on temperature, resulting in lower emissions. The p-
methyl styrene monomer also requires less curing time. Styrene monomer
emissions during curing can be reduced by 50 percent, but some of these
styrene emissions are replaced by non-styrene VOC emissions.
It should be noted that emissions from overspray are not necessarily
reduced by using p-methyl styrene resins. The emission reductions are a
result of less evaporation of the volatile constituents in the resin due to
shorter curing times and lower vapor pressures of the monomer. For
conventional resins, AP-42 emission factors are based on 10 percent loss from
overspray and 8 percent loss from evaporation during cureout. Emission
reductions achievable from using low vapor pressure monomers in place of
styrene monomer are dependent on the substitute monomer used and the amount of
styrene replaced. For the model plants presented in Section 5, total plant
styrene emissions could be reduced by 16 percent, and total plant VOC
emissions by approximately 10 percent.
A major disadvantage to the use of p-methyl styrene-based resins is that
p-methyl styrene monomer costs nearly twice as much as styrene monomer.
Currently, there are very few chemical companies in the United States that
manufacture p-methyl styrene, therefore limiting its availability. However,
this would be expected to change if requirements imposed by regulatory
actions resulted in a market for p-methyl styrene.
Fiberglass boat manufacturers have experimented with resins which contain
other low vapor pressure monomers such as vinyl toluene and dicyclopentadiene
(DCPD). Typically these compounds are substituted for 3 to 5 percent of the
47
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styrene in the resin. The styrene content in the resin may be reduced to 30
to 35 percent. however the total monomer content may still be over 40 percent.
Vinyl toluene and DCPD have similar physical properties to p-methyl styrene,
but may be more economically attractive and more readily available.
Vapor Suppressed Resins- -
Vapor suppressed resins contain additives which reduce VOC emissions
during resin curing. The most co on vapor suppression additives are
paraffins, which migrate to the surface of the resin layer and reduce the
volatilization of free styrene during resin curing. Emissions reductions
ranging from 30 to 50 percent can be achieved, relative to emissions from
conventional resins. For the model plants shown in Section 5, this would
reduce total plant styrene emissions by 20 to 35 percent.
In certain applications vapor suppressed resins can be substituted
directly for conventional resins. They have been used successfully by spa
manufacturers and reportedly used by some boat manufacturers who produce their
entire product from one continuous resin application.’°” 62 In general,
however, most boat manufacturers have not been able to achieve satisfactory
strength performance with vapor suppressed resins as a result of poor
secondary (i.e., interlaminate) bonding.
When vapor suppressed resins are used, the air/resin interface is
separated by a wax film which limits the diffusion of oxygen to the resin
surface. Oxygen normally plays an important role in the curing process by
forming weak surface bonds with the resin, thereby occupying potentially
reactive surface sites as the bulk of the resin polymerizes. These weak resin
surface/oxygen bonds are displaced when the next laminate layer is applied,
which allows resin/resin bonds to form between layers. When paraffin-based
suppressants are used, the lack of oxygen at the resin surface caused by the
wax film allows the active surface sites to react with each other completely.
This results in a fully cured surface not amenable to cross-linking with
subsequent laminate layers.
48
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Surface sanding and/or solvent wiping can be used as a means of
alleviating the secondary bonding problems. The surface of each laminate
layer must be prepared by sanding off the wax layer to create an improved
surface for mechanical bonding. A typical mid-size fiberglass boat contains
four to six laminate layers. The labor intensive step of sanding the wax layer
between application of each laminate layer is estimated to add approximately
four to eight hours of additional labor time per boat.’ 3
Vapor suppressed resins have been commonly used in Sweden since 1982.64
They have also been used at a few boat plants in the United States. The boat
plants that have been successful with using vapor suppressed resLns typically
are manufacturing their boats from start to finish with no cureout allowed
between laminate layers. Since insufficient time is allowed between
application of layers for complete reaction of the resin surface, the
laminate layers can effectively bond to each other as the boat is constructed.
This process is adequate for small boats which do not require high strength
characteristics such as flat water canoes and row boats.
A disadvantage to this “start-to-finish” approach is that the final
product strength is less than the strengths achieved when total cureout
between layers is allowed. Most boat manufacturers seek to.maximize product
strength due to the demanding use of the product and the high costs associated
with product liability concerns. The need to maximize strength is
particularly important in the case of high performance boats. As a result, at
most high performance boat manufacturing facilities, individual laminate
layers are allowed to cure before subsequent layers are applied. This
manufacturing procedure results in significantly increased boat strength and
improved overall product quality compared to the start-to-finish method.
Thus, the need to build boats with complete laminate curing between layers
limits the use of vapor suppressed resins in the fiberglass boat manufacturing
industry. No data were available for a quantitative comparison of laminate
strengths.
49
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However, as is the case for low styrene resins, the advent of SCAQMD Rule
1162 has initiated significant research efforts for developing new vapor
suppressed resins with acceptable secondary bonding characteristics. These
include non-paraffin-based vapor suppressed resins and paraffin-based vapor
suppressed resins with interlaminate adhesion promoters.
The cost of vapor suppressed resins is higher per pound than the cost of
conventional resins. Currently the purchase price of vapor suppressed resins
is 5 to 10 percent higher than conventional resins.
However, the increased labor costs of preparing each layer prior to
applying the subsequent laminate layer must be considered. For the model
plants shown in Section 5, this would result in increased labor costs of
$100,000 to $400,000 per year.
Process Controls for Acetone Emissions
There are three methods available to reduce emissions from acetone.
These are: 1) improving work practices, 2) substitution of water emulsions or
other cleaning solvents for cleanup, and 3) recycle/reclamation of acetone
waste. These controls may be used separately or in combination. A comparison
of the different methods available to reduce VOC emissions from acetone use is
presented in Table 18.
Work Practice Controls- -
Work practice controls reduce acetone use, which in turn reduces acetone
emissions. The key factor in work practice controls is control of acetone
issued to the lamination workers. As discussed in Section 5, the use of hand
protection reduces the number of cleanups required and the use of covered
containers reduces acetone evaporation between cleanups.
Data from a previous survey of VOC controls for boat manufacturing showed
work practice controls can reduce acetone use by an estimated 22 percent. 65
The work practice controls evaluated consist of closed containers at employee
workstations and use of gloves or barrier creams. 66
50
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TABLE 18. COMPARISON OF METHODS TO REDUCE VOC EMISSIONS
FROM CLEAN-UP OPERATIONS
Acetone Usage
with
Improved
Use Water
Based
Use
Dibasic
Work
Practices
Emulsions
Ester
Solvent
Potential 22 % 50 - 75 % 75 %
Emiss ion
Reductions
Applicability Not adequate Potential to
cleaner for completely
hardened gel- replace
coat or acetone.
internal parts
of equipment.
Ease of Resistance by Must install
Conversion workers. heating systems
throughout
plant and keep
cleaner heated
in a hot water
bath.
Potential For High High High
Recycle!
Reclamation
Waste Disposal Spent acetone Non-hazardous Non-hazardous
is a hazardous under RCRA. under RCP .A.
waste. Can dump to Can be
sewer except in biotreated or
rural areas incinerated.
with limited
wr.
Costs Overall costs Overall costs
should be should be
similar to similar to
acetone. acetone.
51
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Alternatives to Acetone- -
A second method to reduce acetone use is to substitute an alternate
cleaner for some aspects of cleanup. There are two different types of
products currently available for use as an alternative to acetone for cleanup:
water based emulsions and lower vapor pressure cleaning solvents.
Water-Eased Emuls ions -
Water-based emulsions are sold under several trade names such as Res-
Away”, Replacetone ”, Thermoclean”, Templex ”, and Mx Fiberglass Liquid
Remover”. The fiberglass boat manufacturing industry has found that these
cleaners are satisfactory for some cleaning tasks but in general do not clean
as well as acetone. 67 ’ The water-based emulsions are not adequate for
cleanup of gel coat or for cleaning internal parts of spray guns. Currently,
Res-Away’ is the most commonly used emulsion, however one large boat company
with 23 plants across the United States is using Templex ”.69
The water-based emulsions can reduce overall acetone usage by
approximately 50 to 75 percent, resulting in significant VOC emission
reductions from cleanup operations. 707 ’ All of the water-based emulsions work
best when heated to over lOOF. A number of boat plants have installed
heating systems in which buckets of the emulsion cleaner are placed in hot
water baths at cleanup stations throughout the lamination area. Capital costs
for installing these heating systems were estimated at $3,000-$5,000 per plant
by one boat company. 72
Equipment used for lamination must be completely free of water or other
contaminants or the laminate strength will be affected. Therefore, some
equipment must be rinsed after cleaning with the emulsion-based cleaner. The
final rinse of these tools can be done with acetone or a special drying rinse
sold by the emulsion manufacturer. Emissions of VOC from this final rinsing
step are small in comparison to acetone emissions, but must be considered in
terms of VOC and toxic air releases.
52
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Disposal of used water-based emulsions is usually much easier and less
costly than acetone disposal. The spent emulsion cleaner is collected in a
drum or small settling tank and the sludges are allowed to settle out. The
U.S. Environmental Protection Agency has determined that spent Res AwayN is
considered non-hazardous under the requirements of RCRA. As such, the
sludges can be dried and sent to a sanitary landfill. At some plants, the
liquid portion is reused as make-up for the next batch of cleaner, however
some of the liquid waste must be disposed. In most areas, the liquid waste
has been accepted by local wastewater treatment plants. In rural areas or
areas where wastewater does not undergo secondary treatment, boat plants have
not been allowed to dispose of waste emulsion cleaner to the sewer due to its
high pH and corrosivity. Another alternative is to dispose of it as a
hazardous waste, which is very costly. Boat plants in this situation have not
been able to use emulsion cleaners in place of acetone due to the high
disposal costs.
One issue that boat plants are facing is employee health and safety when
using the water-based emulsions. The product is typically purchased in
concentrated form and is diluted with water to make the appropriate strength
cleaning solution. The concentrated product is very alkaline with a pH of 11
to 12. While diluting with water brings the pH down, it is still very harsh
and employees with sensitive skin have developed rashes and allergic reactions
upon skin contact. Instructions from the manufacturer state that gloves
should be worn when using these cleaners, however employees in the lamination
area are often resistant to wearing gloves for entire eight hour work shifts
due to the discomfort. An additional concern is that boat plants using both
acetone and water-based emulsions have not identified gloves that are
resistant to both compounds. Therefore, employees who work with both gel coat
and lamination must use different gloves when using acetone to clean-up gel
coat and when using water-based emulsions to clean-up resin.
The overall cost differences between the use of acetone and water-based
emulsions have not been well quantified by the industry, partially because the
water-based emulsions have not been used for a long enough period to have
53
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sufficient cost data in place. The manufacturer and distributors of Res-
Away’ estimate that boat plants can realize a cost savings of 20-40 percent by
switching from acetone to Res-Away ’, under ideal conditions. 7 ’ 75 These cost
savings do not take into account the capital costs of equipment to set up
cleaning stations with heating systems.
Acetone costs vary from approximately $l.50-$3.00 per gallon, while Res-
Away’ costs approximately $12.00 per gallon in its concentrated form. Res-
Away’ is typically diluted 10 to 1 or 12 to I with water resulting in actual
cost per gallon of $1.10. Further cost savings are realized because the Res-
Away’ evaporates at a much slower rate than acetone, and disposal costs of
spent Res-Away ’ are lower than disposal of spent acetone.
Boat manufacturers have been more conservative in their initial cost
comparisons between use of acetone and use of water-based emulsions.
Generally, the industry feels that cost differences will be negligible when
they consider capital costs of installing heating systems, differences in
purchase price of the products, amount of each product needed to clean
equipment and differences in disposal costs.
Low Vapbr Pressure Solvents- -
Another alternative to acetone for cleanup is the use of a lower vapor
pressure solvent. Research and development activities by chemical
manufacturing companies and by a few boat manufacturers indicate that dibasic
ester compounds are suitable for cleaning resins and gel coats. These
compounds have much lover vapor pressures than acetone and consequently result
in lower emission rates.
Currently, DuPont has a dibasic ester cleaning solution available which
they are marketing to the fiberglass boat industry. 76 77 BASF and GAY are also
working with one of the large boat manufacturing companies to formulate a
suitable dibasic ester cleaning solution.
54
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A number of boat plants were identified that are experimenting with this
cleanup alternative, however during this study only a few small boat plants in
California were identified that are actually using it in their production
area. This alternate product for resin cleanup is very new on the market and
the plants contacted had only.been using it for a few months. Boat plants
were not able to provide quantitative data on emission reductions or cost
differences at this time.
Eased on preliminary tests, it is estimated that by switching completely
to a dibasic ester cleaning solution, a reduction in VOC emissions from
cleanup activities of 75 percent over the use of acetone can be achieved. 78
There are still some VOC emissions from the cleanup activities but they are
much lower because the dibasic esters have much lower vapor pressures than
acetone (0.2 mm Hg at 20°C for DEE versus 266 mm Hg for acetone).
In terms of costs, the dibasic ester cleaner is currently two to three
times more expensive to purchase than acetone. However, it lasts longer
because it evaporates at a slower rate. Therefore, much less material is
purchased over time. The product can be recycled by passing it through a
distillation column to remove impurities. The sludges that accumulate are a
liquid waste that are currently not considered hazardous under RCRA
definitions. This liquid waste can be incinerated, and because of its high
heat content, incineration can be a cost effective solution to waste disposal.
Because the DEE is non-hazardous, the disposal costs are much less than
disposal of waste acetone. One boat company estimated the incremental cost of
switching from acetone usage to use of a dibasic ester cleaner is $150 per ton
VOC removed per year.
Waste Acetone Recycle/Reclamation- -
Assuming 60 percent of the acetone used in clean-up at fiberglass boat
plants is emitted in the lamination area, the remaining 40 percent is waste.
If the waste acetone is allowed to evaporate, plant acetone emissions would
increase by 67 percent. Two methods available to reduce these. emissions are
to recover acetone on-site using a batch still and to ship the waste to a
commercial recycling operation. °
55
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ADD-ON CONTROLS
Due to the high costs, add-on controls typically used in other VOC-
emitting industries have not been applied to boat manufacturing. Even well
designed and operated ventilation systems result in high flow rates and low
VOC concentrations relative to most regulated sources of VOC. As previously
discussed, styrene concentrations may not exceed a 100 ppmv time-weighted
average in the workplace of fiberglass boat manufacturing facilities. 8 ’ Since
these facilities typically induce ventilation to comply with the 100 ppmv
level, the concentrations in the spray booth and building exhausts will be at
or below 100 ppmv. The calculated average annual values previously shown in
Tables 13 and 14 range from 1 to 24 ppmv. Available industry data show that
the average concentrations may go as high as 80 ppmv. 82
It should be noted that other sections of the fiberglass reinforced
plastics (FRP) industry, such as continuous lamination, tank coating, and
synthetic marble operations, have higher VOC concentrations in their exhaust
streams than boat manufacturing. Styrene concentrations determined during
source testing at three facilities are shown in Table These differences
in concentration should be considered when evaluating the use of control
technologies being applied in other segments of the fiberglass reinforced
plastics industry to boat manufacturing.
An integral component of any add-on control system applied in the
fiberglass boat manufacturing industry is the capture system for VOC-laden
air. For control purposes, it is advantageous to minimize the exhaust flow
rate and maximize the VOC concentration of exhaust air. Unfortunately,
lowering air turnover ratios in work areas can create another problem,
personnel exposure to styrene. The primary reason for high exhaust flows and
56
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TABLE 19. EXHAUST AIR VOC CONCENTRATIONS FOR THREE
FIBERGLASS REINFORCED PLASTICS INDUSTRIES
VOC Source
Minimum VOC
Concentration, ppmv
Maximum
Concentration, ppmv
Continuous Laminationb
2
1,100
Tank Coating
82
405
Synthetic Marble
10
22
aReference 84.
bcontinuous lamination consists of mechanical lamination of resin and
reinforcing material on an in-line conveyor.
57
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low VOC concentrations found in this industry is the concern for worker
exposure to styrene and the 100 ppmv styrene exposure limits established by
OSHA. The traditional method of meeting this exposure limit has been to
simply move large volumes of fresh air through the work area. As a result,
effective control from both a technical and cost effective perspective has
been difficult to achieve in the fiberglass boat manufacturing industry.
Although there have been attempts in the fiberglass boat manufacturing
industry to reduce exhaust air flow rates while maintaining compliance with
OSHA regulations, it was not possible, in this study, to quantify the success
of such efforts. Intuitively, confinement of the major VOC sources (e.g.,
gel coat and lay-up operations) to well-designed and well ventilated booths or
bays would facilitate reduction in plant exhaust flows. However, based on the
limited amount of information obtained on this issue, it appears that
achievable flow reductions are relatively small. The only example of
successful flow reduction that can be cited from the efforts of this study is
a plant in Michigan.’ This facility was designed with isolated bays for gel
coat, lay-up, and finishing operations. To minimize flow, exhausts from the
gel coat bays are recirculated back into other areas when gel Coat iS not
being sprayed.
Based on a comparison of typical exhaust Concentrations (1 to 24 ppmv)
and the OSHA exposure limits for styrene (100 ppmv), the potential exists for
more effective capture of VOC. Effective capture of the VOC emissions could
offer two benefits. First, the VOC-laden exhaust stream is more amenable to
add-on control techniques. Since, the removal efficiency of most control
techniques drops considerably at very low VOC concentration (<20 ppmv), a
higher degree of VOC control can be achieved. Additionally, the capital and
operating costs of the add-on control are greatly reduced. A secondary
benefit, especially in colder climates is the savings in space heating costs,
since much lower volumes of fresh air would be moved through the building.
This benefit has been the driving force for the limited flow reduction
applications in the boat manufacturing industry.
58
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Another factor which should be considered is that based on a resin/gel
coat ratio of 7/1, gel coat application and curing produces approximately
30 percent of the styrene emissions. However, based on the model plant
ventilation systems developed as part of a submission from the Society of the
Plastics Industry made in response to recent OSHA rulemaking on styrene
exposure, the gel coat spray booth exhaust may account for as little as
10 percent of the total. plant exhaust.” Therefore, highly efficient controls
applied to gel coat booths could potentially reduce emissions by approximately
27 percent. This would only be the case where gel coat operations are
performed in a separate enclosed spray booth separate from lamination. This
is most likely to occur in medium and large size plants manufacturing small
boats (<30 feet). 87
The remainder of this section discusses add-on control technologies which
could be used in the boat manufacturing industry. The devices may be divided
into three general groups: incineration, adsorption systems, and absorption
systems (vet scrubbers). Of the add-on control technologies evaluated in this
study, incineration is the only demonstrated and readily available technology
for controlling VOC emissions from fiberglass manufacturing facilities.
Information on the possible adsorption and absorption technologies is provided
with a discussion of the potential advantages and disadvantages.
Where available, cost data are presented for these systems. The costs
presented are order-of-magnitude cost estimates only. For illustrative
purposes, costs are based on control of gel coat spray booths only for a
medium size plant producing small boats. For illustration purposes, the
combined gel coat spray exhaust flow rate is 14,400 acfm with a total average
VOC concentration of 44 ppinv. This example was selected because it would be
the most cost-effective portion of the exhaust to apply add-on controls due to
its higher concentration relative to the total plant exhaust.
59
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Incineration- -
Two types of incinerators are available, thermal and catalytic. Both
destroy the VOC through oxidation to carbon dioxide and water. In thermal
incineration, the solvent-laden air is exposed to a high temperature of
approximately l,600F (870’C) and are contained in a direct flame combustion
chamber for a period of approximately 0.75 seconds. Catalytic incinerators
use a catalyst bed to oxidize the organic vapors and operate at reduced
temperatures of 750 to l,000F (400 to 540C). Important incineration
design factors are combustion chamber residence time, gas stream flow rate,
operating temperature, and gas stream fuel value.
The heat content of exhausts from boat manufacturing is negligible due to
the low VOC concentrations previously discussed. Therefore, supplemental fuel
is needed to raise the exhaust to the required operating temperature. Heat
recovery equipment is nearly always used with incinerators applied to low VOC
concentration streams to reduce the amount of supplemental fuel required. The
amount of heat recovery achievable can be up to 95 percent. 8 ’ Heat recovery
is accomplished by exchanging heat between the incinerator exhaust and the
incoming air and/or stream to be treated.
Ceramic heat exchange media is sometimes used to achieve very high energy
recovery (95 percent). 89 Other types of incinerators use metal air/air heat
exchanges. Generally, the more energy efficient incinerators have lower
operating costs but higher initial capital costs.
For the higher end of the range of VOC concentration levels encountered
in fiberglass boat manufacturing (i.e., 20 to 80 ppmv), incinerators would be
expected to achieve 90 to 95 percent VOC destruction or greater. Based on
information provided in the Control Technologies for Hazardous Air Pollutants
Handbook, thermal incinerators are capable of achieving at least 95 percent
VOC destruction for streams with VOC contents above 20 ppmv and catalytic
incinerators are capable of achieving 90 percent VOC destruction for inlet VOC
concentrations above 50 ppmv. 9 °
60
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The costs of applying incineration to fiberglass boat manufacturing are
high due to the large air volumes and low pollutant concentrations typically
encountered. For this reason, incinerators have not been applied in this
industry. As an example, the total capital cost of a thermal incinerator with
a 70 percent efficient heat exchanger to control a 14,400 scfm vent stream
would be over $500,000. Fuel costs alone would exceed $40,000/yr based on a
natural gas price of $2.69 per million Btu. If the gel coat booths were
controlled for a medium size plant producing small boats, the total annualized
cost would be over $120,000 per year. The emission reduction would be 8 tons
per year based on an estimated achievable destruction efficiency of
90 percent. This equates to a cost of approximately $15,000 per ton of VOC
removal.
Gas Absorption- -
As previously mentioned, gas absorption is not a proven technology for
controlling VOC emissions from fiberglass boat manufacturing facilities.
However, there are two systems currently under development that may be
candidates for the fiberglass boat industry: the Styrex’ system and the
Chenttact’ system. This section discusses the current technology on these
systems along with a general discussion of the principles of gas absorption.
Gas absorption is a mass transfer operation in which one or more soluble
components of a gas mixture are separated from the mixture by selective
dissolution in a liquid. The absorbed components can be recovered from the
liquid or solvent by stripping or desorption or other recovery techniques. A
typical absorption system with stripping tower is shown in Figure 4.
Gas absorption equipment is designed to provide thorough contact between
the gas and the liquid solvent. The rate of mass transfer between the two
phases is primarily dependent on the surface area exposed. Additional factors
that govern the absorption rate include the solubility of the gas in the
particular solvent and the degree of chemical reaction. These factors;
however, are generally independent of the equipment used. The types of
equipment that are typically used for gas-liquid contact operations include
61
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Ak Dlschwg.
Cooling W .r
(p.ck.doi
kay column)
Cooling W .t
Organics
(p.ck.dor
key column)
Rkh So
S$.sm
Figure 4. Absorption System with Stripping Tower and Solvent Recycle
-------
packed towers, plate or tray towers, spray chambers, venturi scrubbers, and
vessels with sparging equipment. The use of spray chambers, venturi
scrubbers, and sparging is generally limited to the control of particulate
matter and highly soluble gases requiring very few transfer units and are nb C
frequently used for the control of VOC emissions in dilute concentrations. 91
A coon factor used to indicate the operating limits is the absorption
factor. The absorption factor, A, is the ratio of the slope of the operating
line to the equilibrium line, the two curves used in theoretical design of
absorption systems. Values of A less than unity indicate that the fractional
absorption of solute is definitely limited. If A is greater than 1, any
degree of absorption is possible. For a given equilibrium system there will
be a value of A for which the most economical absorption results. A rule of
thumb s that the most economical A will be within the range of 1.25 to 2.0.92
As an emission control method, gas absorption is most widely used for the
removal of water-soluble inorganic contaminants. Water can also be used for
the removal of organic compounds with relatively high water solubilities.
Other solvents, usually organic liquids with low vapor pressures, are used for
organic compounds with low water solubility.” Some important aspects that
should be considered in selecting absorption solvents are listed below:
1. The gas solubility should be relatively high as to enhance the rate
of absorption and decrease the quantity of solvent required.
Solvents chemically similar to the solute generally provide good
solubility.
2. The solvent should have relatively low volatility so as to reduce
solvent lose. This is particularly important in emission control
applications as solvent losses may result in additional VOC
emissions.
3. The solvent should be noncorrosive (if possible) to reduce
construction costs of the equipment.
4. The solvent should be inexpensive and readily available.
63
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5. The solvent should have relatively low viscosity for suitable mass-
transfer rates and flooding characteristics.
6. Ideally the solvent should be non-toxic, nonflammable, chemically
stable, and have a low freezing point.
The technical suitability of gas absorption as a VOC emission control
method is generally dependent on the following factors:
1. Availability of a suitable solvent;
2. VOC removal efficiency required;
3. Recovery value or terminal disposal cost;
4. Capacity for handling vapors; and
5. VOC concentration in the inlet vapor (absorption is usually
considered when the VOC concentration is above 200-300 pprnv).
For the fiberglass boat industry, use of gas absorption to control styrene and
acetone emissions may be limited due to the typically low concentrations and
the low water solubility of styrene. While acetone is infinitely soluble in
water, styrene is only very slightly soluble, thus eliminating water as a
suitable solvent. Identification of an appropriate solvent that can be
regenerated or easily disposed of may be difficult.
The two absorption systems evaluated for their effectiveness in
controlling styrene and acetone emissions are: the Styrex tm absorption system
and the Chenatact* scrubber. The Styrex system uses the proprietary liquid,
Styrex as the absorbent, while Chemtact uses sodium hypochiorite. Neither
system has been installed in a fiberglass boat manufacturing or related
facility; however, available test data sugggest the potential for reducing
scyrene and/or acetone emissions. The following subsections detail the
findings on the Styrex and Cheintact’ systems.
Styrex* - Styrex acts essentially like activated carbon, the differences
being that rather than the microscopic physical interaction between the liquid
and solid, which acts as an extensive condensation surface in activated
64
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carbon, Styrex’ exhibits unsaturated vacancies. These vacancies achieve the
same effect as in activated carbon, but on a molecular level. Vapors are
attracted to the unsaturation points by Van der Waals forces (weak inter-
atomic forces) and trapped without chemical change. The entrapped gas may be
removed, as with activated carbon, by heat stripping, steam stripping and
distilling, or polymerization of the entrapped molecules into aggregates which
are too large for the vacancies and thus form a precipitate. Polymerization
may be accomplished by means of a catalyst or a phococheinical reaction
employing ultraviolet light. 9 ’
There are two units currently available that operated using the Styrex tm
absorbent: the Blitz Roller’ and the ChemPro’ scrubber. The Blitz Roller tm ,
illustrated in Figure 5, is portable in design and can be positioned inside a
facility. The ChemPro scrubber is illustrated in Figure 6. The Blitz unit
rolls on casters and can be moved from station to station.
Vapor-laden air is pulled in at the bottom of the nine-foot high unit and
passed through two solid pack filter sections of Styrex’. Treated air is
exhausted at the top of the unit. Styrex’ is pumped from a fresh supply drum
and distributed over the upper filter, draining down over the lower filter to
a spent chemical drum. The advantages of the Blitz Rollers is its portability
and size, enabling capture of styrene close to the source. The disadvantages
are the potential disposal problems associated with the spent Styrex’, the
added equipment cost if the unit needs to meet explosion-proof criteria, the
potential maintenance problems resulting from resin overspray, and the need
for skilled personnel to run the unit properly. The Blitz Roller’ is
currently installed in one small plastics prototype facility for demonstration
purposes. No performance test has been made on this unit; however, the
workers have commented on the reduction in odor in the work place.
65
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Figure 5.
Cross-sedion Schematic of the Blitz RoHer
66
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York MI*
Em n j 0 Stag.
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C*.n.ry Gr$ds hydraulicaity support
s co mn ab
DePending on th. app1Ic 1on 1 & singi.
or du .n y Gild wft!i comput.C
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Figure 6. ChemprO’ Scrubber With Catenary Grids
Vapor- qu Ed
Zon.
G wd squid m is chwib ,
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w a sy flclsncy .qu ta98%
67
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The ChemPro scrubber, illustrated in Figure 6, is an add-on unit that is
tied into a facility’s exhaust system. This system operates in the same
manner as the Blitz Roller , but is intended to handle higher flaw rates. The
Cheuipro unit has not been installed in any facility to date.
Vendor efforts are currently underway to establish the commercial
viability of the patented Styrex absorption system. Information on this
system, therefore, is limited to experimental tests and pilot scale test runs.
Two such tests were selected for an evaluation of the Styrex system
capabilities.” The test results to date focus on the Styrex* system’s effect
on styrene emissions. No test data are available regarding its effectiveness
in reducing acetone emissions.
The first test to be discussed is a bench-top evaluation of the Styrex
system, performed by the vendor in August 1985. The purpose of the evaluation
was to determine the effectiveness of styrene control. The bench-top unit
consisted of an air pump, three flow meters, a flask containing resin, a
blender, a submersible pump, condensers, and an infrared (IR) analyzer. A
schematic of this unit is shown in Figure 7.
Clean air was pumped through two parallel rotometers; one leading to a
flask containing a polyester resin with approximately 50 percent styrene and
the other by-passing the flask. The two streams were combined and passed
through a final rotometer to determine the total air flow to the system. From
the final rotometer, the airstream was directed to either the IR analyzer for
concentration measurement or to the scrubber for treatment and subsequent
analysis via a three-way valve.
The scrubber was a modified vita-mix blender. The airstream entered near
the bottom, and after vigorous mixing with the Styrex liquid, exited out at
the top. The Styrex” liquid was recirculated through the blender by a pump
positioned in a reservoir of Styrex’ The Styrex ” was not regenerated prior
to recycle. A total of six runs were performed. As shown in Table 20, runs
1-4 evaluated the styrene removal efficiency versus time at three absorbent
volumes: 1,500 ml, 2,150 ml, and 3,750 ml. Run 5 was performed to determine
68
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3-Wsy V&v.
Cocikig W Oil
If
Cooalng W . b
a’
0
In
Aoaom. s
R.sIn —
— R...Mo and Pump
Carbon Tub.
Air In
Figure 7. SLyrex System Bench Top Pilot Unit
-------
TABLE 20. SUMMARY OF RUNS PERFORMED IN THE BENCH-TOP EVALUATION
OF THE STYREf SYSTEM
Run
No.
Description
*
Average Styrex
Volume in
Blender and
Reservoir (ml)
Recycle
Rate
(mi/am)
Inlet 4
Concentration
(ppmv)
1
2,150
275
151 - 315
2
1,500
275k
165 - 279
3
3,750
275 b
89 - 229
4
3,750
275
230 - 285
5
3,570e
275
Not Provided
6
Hydrocarbon
emissions test
Decreased after 280 minutes; level not recorded.
blncreased to 500 mi/mm after 410 minutes.
eSpent Styrex from Run 3 passed under ultraviolet light to test regeneration
capabilities.
dCorresponding outlet concentrations for Runs 1-4 can be determined from
Figure 8.
70
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the regeneration capability of the Styrex. and Run 6 was performed to evaluate
the hydrocarbon emissions from the unit. The inlet styrene concentrations for
all of the runs (presented in Table 20) were generally between 90 and 300 ppmv
which is up to 10 times the average voç concentration typical of the
fiberglass boat manufacturing industry.
The outlet concentrations for Runs 1-4 can be calculated from Figure 8.
As shown, the system demonstrated an initial styrene removal efficiency of
90 percent or greater, but decreased with time. Data were insufficient to
determine the liquid to gas ratio for any theoretical comparisons. During
Runs 2 and 3, the effect of recycle rate was evaluated. The recycle rate was
decreased 280 minutes into Run 2 and was accompanied by a drop in efficiency
as noted in Figure 8. During Run 3, the recycle rate was increased to
500 mi/minute (from an average 275 mi/mm) and was accompanied by an increase
in efficiency as noted in Figure 8.
In Run 5, spent Styrex from test 3 was passed under an ultraviolet
liquid sterilizer with a wave length of 254 in. The regenerated Styrex ’ was
retested and showed an initial reduction of 95 percent, but dropped to
—75 percent in a tenth of the time. No test data was provided. During Run 6,
a malfunction of the flame ionization detector used to determine the total
hydrocarbon concentration levels was discovered, rendering the results
unreliable. An estimation of the hydrocarbon contribution of the Seyrex tm
alone was later estimated at less than 4 ppinv. A breakdown of the speciated
hydrocarbons was not provided.
The next series of tests were run at a glass fiber reinforced plastics
fabrication facility. The tests were performed using the Model 1000 ChemPro
stainless steel pilot unit, outfitted with two elements of the patented
Catenary Grid, as shown in Figure 6. Styrex was fed only to the lower grid.
Air volumes were adjusted to maintain a constant grid pressure drop between 4
and 4.5 inches of water. Approximately 100 gallons of Styrex’ was charged to
the system. Two recirculation rates were evaluated: 5 and 9 gallons per
minute (gpm). Due to low shop activity, the inlet of the unit was spiked with
71
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N.
‘N
I I I I
d Th. —
N
‘N
N,
ii
0
4 Rm4 150 yr
with oon .cycI. .)
- I I I
400 _
d Tbns —
b) Run 2(1500 m l 8tyta
wiSh d.ct hi ,.cyd. r*.)
N
;:j
400
Fh TW. —
I
c P.a ia(31&Jnt btyr.i
w i k cro.o hi iscyci. rd.)
FIgure 8. Results from Styrex tm System Bench-top Tests
-------
fiaaes from the evaporation of styrene monomer to raise the inlet concentration
to approximately 100 ppmv. Concentration measurements were made using an MSA
Samplair pump and MSA styrene-specific length-of-stain detector tubes.
At a recirculation rate of 9-10 gpm, the Styrex demonstrated an initial
styrene removal efficiency of approximately 85 percent, but dropped to
approximately 35 percent in 80 minutes. The inlet air flow rate was measured
at 720 cfa which yields an L/G ratio (slope of the operating curve) of
13.9 gallons Styrex /1000 cfm. The liquid residence time was 10 minutes. At
a recirculation rate of 5 gpm, the Styrex demonstrated an initial efficiency
of almost 90 percent, dropping to 30 percent in 80 minutes. The L/C ratio was
6.9 gallons/1000 cfm and the residence time was 20 minutes. Without
styrene/styrex equilibrium data, it is difficult to assess these operating
conditions.
Although some testing has been done to verify the capability of Styrex
to absorb styrene, further work is required to assess the capability of
Styrex” systems control VOC emissions from to the fiberglass boat
aanufacturing industry. This should include:
I. Development of Styrex*/styrene equilibrium data and theoretical
evaluation of the absorption potential;
2. Demonstration of continuous regeneration and recycle of the Styrex ;
3. Evaluation of the effect of Styrex on acetone, or vice versa;
4. Determination of the expected amount of waste generated from
regeneration; and
5. Full economic analysis of a conunercial unit including waste disposal
costs.
Chetntact’ System - - The Cheintact system is an air scrubber which uses a
fine mist of sodium hypochlorite solution to absorb and oxidize airborne
chemical contaminants. A schematic of the system is provided in Figure 9.
The basic system includes a fiberglass reaction chamber, a nozzle for
73
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Sodum
__
1 ::: _J No
I
._ P. tIon
c1 %ST bSI
Exfl.u*_
Slick =
Exhsu
_ ni ______
Figure 9. Chemtact’ Chemical Scrubber using Atomizing Nozzle
and Sodium Hypochlortte Solution
74
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atomizing the sodium hypochiorite solution, inlet and outlet air ducts and a
drain. An exhaust fan is used to draw contaminated air into the reaction
chamber.
The primary operating feature of the Chemtact system is the spray nozzle
located at the top of the chamber. The nozzle atomizes the sodium
hypochiorite solution into droplets 10-12 microns in size. The sodium
hypochiorite mist is sprayed from the top of the tower where it mixes with the
contaminated air. The mass transfer process of gas absorption takes place at
the interface between the liquid droplet and the surrounding gas phase.
chemical contaminants are absorbed through the interface and into the sodium
hypochiorite droplet where oxidation takes place. Smaller droplets equate to
an increase in the overall gas-liquid interface surface area. This provides
for an increase in removal efficiency.
There are approximately 120 Chemtact m scrubbers in operation at paint
plants, rendering plants, resin cookers, food processors, and waste water
treatment plants. No Chemtact scrubbers are currently in operation or have
been tested in a fiberglass manufacturing facility.
Test data obtained from a. Chemtact m system in operation at a composting
facility indicates a reduction in styrene concentration from 2.00 to 0.12 ppmv
(94 percent removal) and a reduction in acetone concentration from 114 to
3.40 ppmv (97 percent reduction). Similar removal efficiencies are given
for other VOC compounds. These test data indicate the Chemtact m system has
the potential to achieve high VOC removal efficiencies. The composting
facility test data does not include information on treatment flow rates or
system configuration. Such engineering data would be essential for a more
thorough assessment of the applicability Chemtact ’ system to controlling
emissions from fiberglass boat manufacturing plants.
Current Chemtact m systems are able to discharge liquid waste directly to
municipal sewage facilities, due to low concentrations of contaminants being
treated.’ Further evaluation of the liquid effluent is necessary to
determine the efficiency of the sodium hypochlorite oxidation process.
75
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Chemtact removal efficiency data were generated by analyzing air samples from
the inlet and outlet air ducts. Therefore, the calculated efficiencies
reflect the absorption of compounds from the gas phase into the liquid phase,
and not the efficiency of the oxidation process which occurs in the liquid
phase. Testing of liquid effluent samples could be used to evaluate the
efficiency of th. oxidation process. Such information may be important at
larger facilities where waste water discharge rate from a Chemtact system may
be significant. Effluent data could not be obtained for this evaluation.
The capital investment for a 14,400 acfa system is approximately
$130,000. The operating costs are estimated to be $11,000/year including the
cost of chemicals and electricity. These costs do not include installation of
ventilation duct work which would be required to capture and deliver VOC
contaminated air to the Chemtact’ system. This cost also does not include any
permits or waste disposal fee associated with the installation of such a
system. 101
This system has been demonstrated to successfully remove odors at flow
rates ranging from 100 to 80,000 cfa. Treatment flow rates in excess of
100,000 cfa have been obtained with the use of multiple units. As discussed
earlier, it may be possible to reduce the flow rate of air requiring treatment
significantly through the use of ventilation stations located at individual
work areas in the plant where the majority of VOC emissions occur. This could
potentially reduce the size, and therefore the total cost of the treatment
system.
Adsorption- -
The use of adsorption devices has not been demonstrated for controlling
VOC emissions from fiberglass boat manufacturing facilities. The following
discussion presents the fundamentals of adsorption and the technical
limitations of applying adsorbers to the fiberglass boat industry.
Adsorption is a mass-transfer operation involving interaction between
gaseous and solid phase components. The gas phase (adsorbate) is captured on
the solid phase (adsorbent) surface by physical or chemical adsorption
76
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mechanisms. Physical adsorption is a mechanism that takes place when
intermolecular (van der Waals) forces attract and hold the gas molecules to
the solid surface. Chemisorption occurs when a chemical bond forms between
the gas and solid phase molecules. A physically adsorbed molecule can readily
be removed from the adsorbant (under suitable temperature and pressure
conditions) while the removal of a chemisorbed component is much more
difficult.
Activated Carbon Adsorption- -
The most commonly used industrial adsorption systems are based on
activated carbon as the adsorbent. Activated carbon is effective in capturing
certain organic vapors by the physical adsorption mechanism. In addition,
adsorbate may be vaporized for recovery by regeneration of the adsorption bed
with steam. Oxygenated adsorbents such as silica gels, diatomaceous earth,
alumina, or synthetic zeolites exhibit a greater selectivity than activated
carbon for capturing some compounds.
The design of a carbon adsorption system depends on the chemical
characteristics of the VOC being recovered, the physical properties of the off
gas stream (temperature, pressure, and volumetric flow rate), and the physical
properties of the adsorbent. The mass flow rate of VOC from the gas phase to
the surface of the adsorbent (the rate of capture) is directly proportional to
the difference in VOC concentration between the gas phase and the solid
surface. In addition, capture rate is dependent on the adsorbent bed volume,
the surface area of adsorbent available to capture VOC, and the rate of
diffusion of VOC through the gas film at the gas and solid phase interface.
Physical adsorption is an exothermic operation that is most efficient within a
narrow range of temperature and pressure. A schematic diagram of a typical
fixed bed, regenerative carbon adsorption system is shown in Figure 10.
The inlet gases to an adsorption unit are typically filtered to prevent
bed contamination. Vapors entering the adsorber stage of the system are
passed through the porous activated carbon bed. Adsorption of inlet vapors
occurs in the bed until the activated carbon is saturated with VOC. When the
77
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V.nt Str.am
H.I E ch ng
4op t$on.I)
Amblint
Au InIM .
1w CoollnglDiylng
Ph... to
D spossI 01
Tis.tment
FilS.
Blowsi
Vent
Ftltw
Condnsr
Oig.nuc Ph.s. to R.covsiy
Figure 10. Carbon Adsorber System process Flow Diagram
-------
bed is completely saturated resulting in breakthrough, the incoming VOC-laden
gases are typically routed to an alternate bed while the saturated bed is
regenerated, usually with steam.
There are no known applications of carbon adsorption to fiberglass boat
manufacturing. One concern is the emission reduction associated with low VOC
concentrations. The emission reduction achievable with carbon ad.sorbers
decreases rapidly when the inlet VOC concentration drops below 100 ppmv.’° 2
As stated previously, average VOC concentrations can range from 1 to 80 ppmv
for the fiberglass boat manufacture industry. An additional concern is
polymerization as styrene on the carbon. Polymerization of styrene on the
carbon, if it occurred, would quickly deactivate the bed.
A second concern is the potential for bed fires when adsorbing ketones,
such as acetone. The reason for this bed fire potential is that ketones have
a high heat of adsorption. However, in other industrial applications, it has
been shown that if proper operation procedures are followed, bed fires can be
avoided. 103 Proper procedures for controlling heat build up in the bed
include: (1) using low ash (low metals) carbon, since metals are believed to
catalyze exothermic reactions with ketones; (2) ensuring constant and even air
flow through the bed to remove heat; (3) preventing high concentration and low
air flow conditions; (4) installing instrunientation to monitor temperature
conditions; (5) installing an emergency water cooling system; and (6)
desorbing the solvent or blanketing the bed with nitrogen prior to system
shutdown.
Another major concern is the vast difference in the capacity for carbon
to adsorb acetone versus styrene. At .0002 psia, the adsorptive capacity for
styrene is 30 percent, while the adsorptive capacity for acetone is only 1 to
2 percent, thus making the removal of acetone the limiting design criteria. 104
Conventional carbon adsorption systems have traditionally been applied to
streams with VOC contents in the range of 1,000 to 10,000 ppmv to recover
79
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solvent for reuse. With high flow/low concentrations, streams such as those
found in boat manufacturing, costs of carbon adsorption is expected to be
high.
For a 14,400 scfm flow rate the installed capital cost for a conventional
carbon adsorption system would be approximately $500,000. Annual operating
costs would be approximately 5 percent of the initial capital investment or
$25,000/yr. The total annualized cost would be approximately $109,000.
There are several variants of the system previously described which use
the same adsorption mechanisms. The first system uses a fibrous activated
carbon adsorbent formed into a honeycomb. The honeycomb continuously rotates.
Zones of the structure alternately pass through the VOC laden stream and a
stream of hot air used for desorption. The hot air stream, which has a much
higher concentration of VOC, must then be treated using a conventional carbon
adsorber or incinerator. 103
As stated previously there are no known applications of carbon adsorption
to fiberglass boat manufacturing. There is, however, a fiberglass horse
trailer manufacturing site that is currently using a carbon adsorber to
control styrene emissions. No data was available to determine t1 e efficiency
of the system, however, an appreciable reduction in odor was noted by
neighboring facilities. This site has not experienced problems with
polymerization of styrene on the carbon. The ad.sorber is a tower of 48 trays
approximately 2 feet square and 1 inch deep each. The trays are sent off-
site for high temperature regeneration at a cost of $7 to $9 per tray. The
trays are changed out every two to four months.’°’
The trailer facility is relatively small compared to a boat manufacturing
facility, therefore, cycle times for tray regeneration may be less frequent
than would be expected for a boat manufacturing facility. No appreciable
amount of acetone is in the exhaust to the adsorber.
Although this facility has not experienced any operational problems, the
potential for operational problems still exists in the application of
80
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integrated carbon adsorption systems at boat plants. First, the styrene
emissions from boat plants would typically be much higher. At higher styrene
emission rates, polymerization of the styrene is more likely to occur.
Secondly, the carbon is sent off-site for high temperature regeneration. Even
if styrene polymerized on the carbon, it would not present a problem. The
polymer would be burned off by the high temperature regeneration. However,
for the VOC emission rates at most boat plants, integrated carbon adsorption
systems (with on-site regeneration capabilities) would likely be more
practical and more economic. The VOC reduction efficiency of these systems
would be more sensitive to polymerization. Regeneration with hot steam or
nitrogen would not remove polymer deposits as effectively as the high
temperature regeneration, and a significant portion of the adsorption sites
may be deactivated permanently.
Polyad Adsorption System- -
The Polyad system uses a fluidized bed containing a macroporous polymer,
Bonapore’. The polymer continuously circulates between the adsorption and
desorption sections. ‘No facilities using this technology are currently in
operation in Sweden. One uses the process to control exhaust air emissions
from a furniture painting spray booth, and the other to control exhaust air
emissions from a spray booth used for making various polyester products. 107
No test data was available to determine the efficiency of the Polyad ’ system
for these two facilities.
This system has not been demonstrated at boat manufacturing operations,
however, the vendor, Nobel Chemetur, is continuing efforts to determine the
applicability of the Polyad system for controlling styrene and acetone
emissions.
81.
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82
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16. Telecon. Barnett, K., Radian Corporation, with Antice, E., Frees, Inc.
December 21, 1988. Conversation concerning design of boat manufacturing
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HIll Publication. 1984. pp. 152-155.
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27. Reference 26.
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29. Article on Hatteras Yachts use of resin transfer molding. Davis, D.,
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Mold Plastics Industries. East Carolina University, Department of
Manufacturing. 1987. p. 34.
30. Telecon. Barriect, K., Radian Corporation, with Boyd, D., Daniel P. Boyd
and Company. December 1988. Conversation concerning fiberglass boat
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31. Reference 11, pp. 4-18.
32. Reference 9, pp. 41-42.
83
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33. Todd, V., Control of Styrene Vapor During Hull Fabrication in Large Boat
Production. National Institute for Occupational Safety and Health
Centers for Disease Control - Cincinnati, Ohio, NTIS P3-84-239441, 1983,
p. 3.
34. Reference 20, Section 4-1.
35. Telecon. Barnett, K., Radian Corporation, with Gerdon, D., Glidden
Paint. August 14 1981. Conversation about fiberglass boat gel coats.
36. Reference 26, p. 102.
37. Reference 15.
38. Elsherif. Staff Report, Proposed Rule 1162 Polyester Resin Operations,
South Coast Air Quality Management District, Rule Development Division,
El Monte, California. January 23, 1987.
39. Reference 26, P. 103.
40. Telecon. Howle, R., Radian Corporation, with Morrison, M., Sea-Ray
Eoats. August 17, 1981. Conversation about fiberglass boat making.
41. Reference 26.
42. Reference 26, p. 110.
43. Reference 2, Appendices C and D.
44. Telecon. Barnett, K., Radian Corporation, with McDermott, J., Consultant
to Fiberglass Fabrication Association. November 23, 1988.
45. Reference 26.
46. Telecon. Barnett, K., Radian Corporation, with Spivey, S., Society of
the Plastics Industry. March 3, 1989.
47. Reference 26.
48. Reference 26.
49. Reference 46.
50. Reference 18.
51. Reference 18.
52. Reference 2.
53. Letter and enclosures from Goodman, D., Glass-Craft, Inc., to L. Rhodes,
Radian Corporation. January 12, 1989.
54. Reference 53.
84
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55. Reference 53.
56. Reference 20.
57. Telecon. Stockton, M. B., Radian Corporation, with Ballard, R., Alpha
Resins, Inc. May 19, 1988.
58. Telecon. Barnett, K., Radian Corporation, with McDonald, M., JEM
Plastics. February 13, 1989. Conversation concerning polyester resins
used in boat manufacturing.
59. Reference 26, p. 113.
60. Reference 26.
61. Reference 22, p. 175.
62. Reference 22, p. 1.74.
63. Letter and enclosure from Kenson, R., Met Pro Systems Division, to Ewing,
R., Aquatic Systems Inc., March 10, 1988. Submitted to Michigan DNR as
part of a technical supplement of the Four Winns, Inc., Air Permit
Application, April 22, 1988.
64. Reference 22.
65. Reference 26, p. 112.
66. Reference 26, p. 111.
67. Telecon. Barnett, L., Radian Corporation, with Patel, R., South Coast
Air Quality Management District. January 20, 1989. Conversation
concerning solvent use for resin cleanup.
68. Telecon. Barnett, K., Radian Corporation, with Keller, L., Outboard
Marine Corporation. January 9, 1989. Conversation concerning acetone
use.
69. Technical Support Document from Steve Plantz, Thompson Boat Company,
February 3, 1987. Submitted to Michigan DNR as part of a technical
supplement of the Thompson Boat Company, Air Permit Application Nun ber
45-87.
70. Reference 67.
71. Reference 68.
72. Reference 69.
85
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73. Telecon. Stockton, M.B., Radian Corporation, with Richard Lathrup,
Bayliner Marine Corporation. September 8, 1989. Conversation concerning
acetone substitutes.
74. Letter and enclosure from Jacqueline W. Sales, Chief of Regulation
Development Section, Office of Solid Waste and Emergency Response, U.S.
Environmental Protection Agency, October 8, 1986. To Daniel P. Boyd,
Daniel P. Boyd and Company. Determination that spent Res-Away is not
characterized as a hazardous waste.
75. Telecon. Stockton, M.B., Radian Corporation, with Lee Sechier, Resin
Support System, Inc., August 18, 1989. Conversation concerning use of
Res-Away in place of acetone.
76. Telecon. Stockton, M.B., Radian Corporation, with Ken Webber, the Norac
Company, August 22, 1989. Conversation concerning use of Res-Away in
place of acetone.
77. Telecon. Stockton, M.B., Radian Corporation, with Sally McCoach, E.I.
DuPont de Nemours and Company, October 11, 1989. Conversation concerning
Dupont Dibasic Esters.
78. DuPont Dibasic Esters. Solvents, and Intermediates for Industry .
Marketing Brochure describing DuPont’s Dibasic Esters products.
79. Telecon. Stockton, M.B., Radian Corporation, with Bill McDonald,
We].lcraft Marine Corporation. August 18, 1989. Conversation concerning
use of DBE solvents in place of acetone.
80. Reference 26.
81. Reference 18.
82. Camp Dresser and McKee Inc. VOC Emissions - Add-on Air Pollution Control
Equipment Study. Prepared for Boston Whaler Inc., Rockland
Massachusetts. No. 1417-l-RTj. July 9, 1986.
83. Reference 22, p. 4-5.
84. Reference 22.
85. Reference 82.
86. Reference 2.
87. Reference 2.
88. Letter and enclosure from Rafson, H., Quad Environmental Technologies
Corporation, to Rhodes, L., Radian Corporation. September 27, 1988.
89. Reference 88.
86
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90. The U. S. Environmental Protection Agency, Air and Energy Engineering
Research Laboratory. Handbook Control Technologies for Hazardous Air
Pollutants. Research Triangle Park, North Carolina. Publication
No. EPA/625/6-86/0l4. September 1986.
91. The U.S. Environmental Protection Agency. Organic Chemical Manufacturing
Volume 5: Adsorption, Condensation, and Absorption Devices.
EPA-450/3-80-027, NTIS PS81-220543. December 1980.
92. Treybal, R.E. Mass Transfer Operations. McGraw-Hill book Company, New
York, New York, Third Edition, 1980.
93. Reference 91.
94. Cox, J., and K. Cox. Fugitive Methyl Styrene Control: A Breakthrough?
Presented at the 40th Annual Conference, Reinforced Plastics/Composites
Institute, The Society of the Plastics Industry. January 28 to
February 1, 1985.
95. Telecon. Kuo, I. R., Radian Corporation, with Dubiel, A., Modern
Composite Technologies. September 28, 1989. Conversation concerning
Blitz Roller.
96. Letter and attachments from Bilgore, R., Xerodor Corporation, to Kuo, I.,
Radian Corporation. August 3, 1989.
97. Letter and attachments from Rafson, H. J., Quad Environmental
Technologies Corporation, to Kuo, I., Radian Corporation.
October 2, 1989.
98. Letter and attachments from Rafson, H. J., Quad Environmental
Technologies Corporation, to Rhodes, L., Radian Corporation.
September 27, 1988.
99. Reference 98.
100. Telecon. Barnett, K., Radian Corporation, with Rafson, H. Quad
Environmental Technologies Corporation. February 6, 1989. Conversation
concerning Chemtact
101. Reference 100.
102. Reference 90.
103. Memorandum from Barnett, K., Radian Corporation, to Carbon
Adsorption/Condensation Project File. February 29, 1988. Meeting
minutes EPA/Calgon Carbon Corporation. pp. 14-15.
87
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104. Telecon. Elliott, J., Radian Corporation, with Riley, G., Calgon Carbon
Corporation. October 5, 1989. Conversation regarding carbon adsorbers.
105. Reference 104.
106. Telecon. Kuo, I., Radian Corporation, with Johnson, L., Western World.
January 18, 1990. Conversation regarding use of carbon adsorber to
control styrene emissions.
107. Letter and enclosure from Keller, L., Outboard Marine Corporation, to
Barnett; K., Radian Corporation. November 11, 1989.
108. Letter from Daescbner R., Polyad”, Nobel Industries, to Kuo, I., Radian
Corporation. November 1, 1989.
88
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GLOSSARY
OSHA Occupational Safety and Health Administration
PEL Permissible Exposure Limits
89
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TECHNICAL REPORT DATA
(Please read I*w’uctions on the revez e before completing)
1. REPORT NO. 2.
EPA-600 /2- 90-019
3. RECIPIENT’S ACCESSIOM’NO.
4. TITLE AND SUBTITLE
Assessment of VCC Emissions from Fiberglass
Boat Manufacturing
5. REPORT DATE
May 1990
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
M. B. Stockton and I.R. Kuo
I. PERFORMING ORGANIZATION REPORT NO,
239-004-48
). PERFORMING ORGANIZATION NAME AND ADDRESS
Radian Corporation
P.O. BOX 13000
Research Triangle Park. North Carolina 27709
10. PROGRAM ELEMENT NO.
.
11.CONTRACT/GRANTNO.
68-02-4286, Task 48
12. SPONSORING AGENCY NAME AND ADDRESS
EPA Office of Research and Development
Air and Energy Engineering Research Laboratory
Research Triangle Park, NC 27711
13. TYPE OF REPORT AND PERIOD COVERED
Task Final: 1-10/89
14. SPONSORING AGENCY CODE
EPA/600/13
15. SUPPLEMENTARY MOTES AEERL project officer is Charles H. Darvin, Mail Drop 61, 919
541- 7633.
16. INACT The report presents an assessment of volatile organic compound (VCC)
emissions from fiberglass boat manufacturing. A description of the industry struc-
ture is presented, including estimates of the number of facilities, their size, and
geographic distribution. The fiberglass boat manufacturing process is described,
along with sources and types of VCC emissions. Model plants representative of
typical facilities are also described. Estimates of VCC emissions are presented
on per plant and national bases. VCC emissions from this industry consist mainly
of styrene emission from gel coating and lamination, and acetone or other solvent
emissions from clean—up activities. Finally, potential VCC control technologies
are evaluated for this industry, including a discussion of technical feasibility. Lirni-
ted cost data are also presented.
7. KEY WORDS AND DOCUMENT ANALYSIS
I. DESCRIPTORS
b.IOENTIFIERS/OPEN ENDED TERMS
C. COSATI Field/Group
Pollution Acetone
Crganic Compounds Polyester Resins
Volatility
Glass Fibers
Boats
Styrene
Pollution Control
Stationary Sources
Volatile Organic Corn-
pounds (VCCs)
Fiberglass
l3B
07C ill
20M
liE, liE
13J
18. DISTRIBUTION STATEMENT
.
Release to Public
,
19. SECURITY CLASS (This Report)
Unclassified
21. NO. OF PAGES
100
20. SECURITY CLASS (This page)
Unclassified
22. PRICE
EPA Form 2220.1 (9-73)
90
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