United States
Environmental Protection
Agency
Office of Air Quality
Planning and Standards
Research Triangle Park, NC 27711
EPA-453/D-96-016
October 1996
Air
EPA
Guideline Series
Control of Volatile Organic
Compound Emissions from Coating
Operations at Aerospace
Manufacturing and Rework
Operations
DRAFT
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V, ,.
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Guideline Series:
Control of Volatile Organic Compound
Emissions from Coating Operations at
Aerospace Manufacturing and Rework
Operations
U.S. Environmental Protection Agency
Region 5, Library (Pt-l2J)
77 West Jackson Boulevard, 12th Roof
Chicago, IL 60604-3590
Emission Standards Division
U. S. Environmental Protection Agency
Office of Air and Radiation
Office of Air Quality Planning and Standards
Research Triangle Park, NC 27711
October 1996
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This draft report has not been reviewed by the Emission
Standards Division of the Office of Air Quality Planning and
Standards, EPA nor approved for final publication. Mention of
trade names or commercial products is not intended to constitute
endorsement or recommendation for use. The guideline series of
reports is issued by the Office of Air Quality Planning and
Standards (OAQPS) to provide information to State and local air
pollution control agencies; for example, to provide guidance on
the acquisition and processing of air quality data and on the
planning and analysis requisite for the maintenance of air
quality. Reports published in this series will be available from
the Library Services Office (MD-35), U. S. Environmental
Protection Agency, Research Triangle Park, North Carolina 27711;
from the Office of Air Quality Planning and Standards Technology
Transfer Network, U. S. Environmental Protection Agency, Research
Triangle Park, North Carolina 27711; or, for a fee, from the
National Technical Information Services, 5285 Port Royal Road,
Springfield, Virginia 22161.
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TABLE OF CONTENTS
1.0 INTRODUCTION 1-1
2.0 AEROSPACE MANUFACTURING AND REWORK OPERATIONS ... 2-1
2.1 GENERAL 2-1
2.2 PROCESS DESCRIPTION 2-3
2.2.1 Coating Application 2-3
2.2.2 Cleaning 2-6
3.0 EMISSION CONTROL TECHNIQUES 3-1
3.1 COATING SUBSTITUTIONS 3-1
3.2 EQUIPMENT CHANGES 3-2
3.2.1 High Transfer Efficiency Spray Guns . . 3-2
3.2.2 Spray Gun Cleaning 3-5
3.2.3 Conventional High Transfer Efficiency
Application Methods 3-6
3.3 HAND-WIPE CLEANER SUBSTITUTIONS 3-7
3.3.1 Aqueous and Semiaqueous 3-7
3.3.2 Citrus-Based 3-7
3.3.3 Reduced Vapor Pressure 3-8
4.0 PRESUMPTIVE RACT REQUIREMENTS 4-1
4.1 SPECIALTY COATINGS 4-1
4.2 PRIMERS, TOPCOATS, CHEMICAL MILLING
MASKANTS 4-3
4.3 APPLICATION EQUIPMENT 4-3
4.3.1 Exemptions 4-3
4.3.2 Timing (Schedule) of Compliance .... 4-4
4.4 CLEANING OPERATIONS 4-4
4.4.1 Housekeeping 4-4
4.4.2 Hand-Wipe Cleaning 4-5
4.4.3 Flush Cleaning 4-6
4.4.4 Spray Gun Cleaning 4-6
5.0 GUIDANCE TO STATE ENFORCEMENT AGENCIES 5-1
5.1 DEFINITIONS 5-1
5.2 APPLICABILITY 5-2
5.3 COMPLIANCE, MONITORING, RECORDKEEPING &
REPORTING PROVISIONS 5-2
APPENDIX A DEFINITIONS A-l
APPENDIX B AEROSPACE MANUFACTURING AND REWORK
OPERATIONS MODEL RULE B-l
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LIST OF FIGURES
Figure 2-1. Active U.S. aerospace manufacturing
facilities 2-4
LIST OF TABLES
TABLE 2-1. AEROSPACE MANUFACTURING SIC CODES
TABLE 3-1. PERCENT REDUCTION IN COATING (PRIMERS
AND TOPCOATS) EMISSIONS WITH HIGH
TRANSFER EFFICIENCY EQUIPMENT FROM
SECTION 114 DATA 3-4
TABLE 4-1. SPECIALTY COATINGS VOC CONTENT
LIMITS 4-2
IV
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1.0 INTRODUCTION
The Clean Air Act (CAA) as amended in 1990 requires that
State implementation plans (SIP's) for certain ozone
nonattainment areas be revised to require the implementation of
reasonably available control technology (RACT) to control
volatile organic compound (VOC) emissions. The U. S.
Environmental Protection Agency (EPA) has defined RACT as the
lowest emission limitation that a particular source is capable of
meeting by the application of control technology that is
reasonably available considering technological and economic
feasibility. The EPA has issued, and is continuing to issue,
control techniques guideline documents (CTG's) that present
feasible RACT control measures for VOC source categories. The
CTG's recommend "presumptive norms" of control for each source
category, but individual sources may have alternative RACT
requirements imposed by making an adequate infeasibility
demonstration (44 FR 53761, September 17, 1979) .
Section 183(b)(3) of the CAA requires the EPA Administrator
to issue a CTG for the control of VOC emissions from coatings and
solvents used in the aerospace industry. This CTG is intended to
supersede any potential applicability of the Miscellaneous Metal
Part and Products CTG (RACT) requirements for manufacturing and
rework operations of aerospace vehicles and components.
According to the CAA, this CTG guidance should also reflect
control resulting from applying the "best available control (BAG)
measures." Section 183 (e) (1) (A) defines "BAG" as the "most
effective equipment, measures, processes, methods, systems or
techniques, including chemical reformulation, product or
feedstock substitution, repackaging, and directions for use,
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consumption, storage, or disposal." Therefore, this CTG departs
from the approach followed in the other CTG's by not recommending
a single approach for determining RACT, but investigating a range
of approaches to reduce VOC emissions from aerospace operations.
Several optional approaches comprise the presumptive RACT found
in this CTG.
The CTG's are intended to provide State and local air
pollution control authorities with an information base for
proceeding with their analyses of RACT for their own regulations.
The CTG's contain a review of current knowledge and data
concerning the technology, impacts, and costs associated with
various emission control techniques. Where applicable, the EPA
recommends that States adopt requirements consistent with the
presumptive RACT. However, these measures are only a recommenda-
tion; States may develop their own RACT requirements on a
case-by-case basis, considering the economic and technical
circumstances of individual sources. It should be noted that no
Federal laws or regulations preclude States from requiring more
stringent controls than those recommended as RACT. A particular
State, for example, may broaden the applicability by revising the
"aerospace vehicle or component" definition to include models,
mock-ups, prototypes, and production equipment such as molds,
jigs, and tooling. Some States may need additional control in
order to meet the national ambient air quality standards (NAAQS)
for ozone in some areas.
This CTG identifies presumptive RACT for controlling VOC
emissions from aerospace coatings and cleaning solvents.
National emission standards for hazardous air pollutants (NESHAP)
for aerospace manufacturing and rework operations were published
on September 1, 1995 (60 FR 45948). While these final standards
address the reduction of HAP emissions, the control techniques
required by the NESHAP will result in reductions of VOC emissions
as well. In addition, the control techniques required by the
NESHAP are similar to those addressed in this CTG for reducing
VOC emissions. Because the emission reductions, costs, and
environmental impacts have already been determined for major HAP
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sources and are attributed to the NESHAP (see Docket No. A-90-20,
Subcategory II-B), these impacts are not summarized in this CTG.
While the Aerospace NESHAP sets limits for maximum HAP and
VOC content for topcoats, primers, maskants, clean-up solvents,
and cleaning operations, the CTG establishes presumptive RACT
limits for VOC's. The CTG includes requirements for Specialty
Coatings, which are not covered by the Aerospace NESHAP. The
Clean Air Act specifies that solvents will be addressed in the
Aerospace CTG. However, because the CTG is guidance to be
adopted as individual State regulations and SIP's, it does not
specify detailed requirements for monitoring, testing,
recordkeeping, and reporting as the NESHAP has done. Rather, the
States are directed under previous EPA guidance for establishing
RACT (57 FR 13502, April 16, 1992) to develop "enforceable
regulations" containing such requirements. While EPA is
providing an example of such a regulation in the model rule
(Appendix C), this CTG allows States the flexibility to address
those requirements as long as they meet EPA enforceability
criteria.
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2.0 AEROSPACE MANUFACTURING AND REWORK OPERATIONS
2.1 GENERAL
The aerospace industry being evaluated includes all
manufacturing facilities that produce an aerospace vehicle or
component and all facilities that rework or repair these
aerospace products. Aerospace vehicle or component is defined
as, but not limited to, any fabricated part, processed part,
assembly of parts, or completed unit of any aircraft including,
but not limited to, airplanes, helicopters, missiles, rockets,
and space vehicles. In addition to manufacturing and rework
facilities, some shops may specialize in providing a service,
such as chemical milling, rather than actually producing a
component or assembly. In general, aerospace manufacturing and
rework facilities are covered by the SIC codes listed in
Table 2-1. However, facilities classified under other SIC codes
may be subject to the proposed rule if the facility meets the
definition of a major source and the definition of an aerospace
manufacturing or rework facility.
Aerospace facilities may be divided into four market
segments: commercial original equipment manufacturers (OEM),
commercial rework facilities, military OEM's, and military rework
facilities. The commercial OEM segment of the market includes
the manufacture of commercial aircraft as well as the production
of business and private aircraft. The military OEM segment of
the market includes military installations and defense
contractors that manufacture aircraft, missiles, rockets,
satellites, and spacecraft. Rework facilities, both commercial
and military, may rework many of the above end products.
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TABLE 2-1. AEROSPACE MANUFACTURING SIC CODES
SIC Code
3720
3721
3724
3728
3760
3761
3764
3769
4512
4581
9711
Description
Aircraft and Parts
Aircraft
Aircraft Engines and Engine Parts
Aircraft Parts and Equipment
Guided Missiles, Space Vehicles, and Parts
Guided Missiles and Space Vehicles
Space Propulsion Units and Parts
Space Vehicle Equipment
Air Transportation, Scheduled
Airports, Flying Fields, and Services
National Security
Based on information obtained through the Federal Aviation
Administration and the U.S. Department of Commerce - Bureau of
the Census, there are an estimated 2,869 aerospace facilities
that could be subject to this guidance. Of this number,
1,395 produce or rework commercial products, and 1,474 produce or
rework military products. The combined VOC emissions from these
facilities are estimated to be over 213,000 megagrams/year
(Mg/yr) (234,000 tons/yr).
In addition to these facilities, there are numerous
subcontractors that manufacture or rework aerospace vehicles or
components. The subcontractors may work directly for the OEM or
rework facilities, or indirectly through first line
subcontractors. Because most of these subcontractors perform
various types of work, they are often classified under
non-aerospace SIC codes. Consequently, an estimate of the number
of subcontractors cannot be made. One company alone, however,
employs the services of over 5,000 subcontractors.
Aerospace manufacturing facilities and rework operations
typically are located in or near industrial centers in areas of
medium to high population density. Some States with a large
number of aerospace manufacturers are California, Texas,
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Connecticut, Florida, and Washington. Figure 2-1 presents the
number of aerospace manufacturing facilities by State.
Aerospace manufacturing facilities range in size from small
shops that produce a single aerospace component, such as
propellers, to large corporations that produce the entire
aircraft. Aerospace rework facilities, however, are usually
large facilities that must be able to rework or repair every
facet of several models of large commercial or military aircraft.
The hours of operation at aerospace manufacturing and rework
facilities may vary greatly due to the production backlog at each
facility. The hours of operation may range from 8 hours (or
less) per day, 5 days per week, to 24 hours per day, 7 days per
week.
2.2 PROCESS DESCRIPTION
Aerospace manufacturing and rework operations typically
consist of the following basic operations: materials receiving,
machining and mechanical processing, coating application,
chemical milling, heat treating, cleaning, metal processing and
finishing, coating removal (depainting), composite processing,
and testing. Many aerospace manufacturing and rework facilities
may employ all of these processes in their operations, as with an
OEM facility that produces the entire aerospace vehicle.
However, an aerospace facility may only employ a subset of these
operations, as with a facility that produces a single component
or assembly or a facility that provides a service such as
chemical milling. Of these operations, coating application and
cleaning are the significant sources of VOC emissions and are the
processes covered by this Aerospace CTG in the following
sections.
2.2.1 Coating Application
A coating is a material that is applied to the surface of a
part to form a decorative or functional solid film. The most
common coatings are the broad categories of nonspecialized
primers and topcoats that are regulated for major sources under
the Aerospace NESHAP. There are also numerous specialty coatings
covered by this guidance that provide additional performance
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characteristics, such as temperature, fluid, fire resistance,
flexibility, substrate compatibility, antireflection, temporary
protection or marking, sealing, adhesively joining substrates,
enhanced corrosion protection, or compatibility with a space
environment. Each material is different because it must meet
individual performance standards particular to a specific design.
The quality of the coatings is critical to the airworthiness and
safety of the final product. Aerospace vehicle manufacturing is
strictly controlled by the Federal Aviation Administration, the
Department of Defense, and specific customer requirements.
Industry specifications for coatings are dictated by these
requirements.
Most aerospace coatings are solvent-borne, which contain a
mixture of organic solvents, many of which are VOC's. The most
common VOC solvents used in coatings are toluene, xylene, methyl
ethyl ketone, and methyl isobutyl ketone. The VOC content ranges
differ for the various coating categories.
2.2.1.1 Sealing. Sealants, predominately composed of
polysulfide, are applied throughout the aerospace vehicle
structure primarily to seal out moisture and contaminants to
prevent corrosion, such as on faying (i.e., closely or tightly
fitting) surfaces, inside holes and slots, and around installed
fasteners. They are also used to seal fuel tanks and pressurized
components. Sealants are applied using tubes, spatulas, brushes,
rollers, or spray guns. Sealants are often stored frozen and
thawed before use, and many are two-component mixtures that cure
after mixing. Typically, a sealant is applied before assembly or
fastener installation, and the excess is squeezed out or extruded
from between the parts as the assembly is completed. This
ensures a moisture-tight seal between the parts.
2.2.1.2 Adhesive Bonding. Adhesive bonding involves
joining together two or more metal or nonmetal components. This
process is typically performed when the joints being formed are
essential to the structural integrity of the aerospace vehicle or
component. Bonding surfaces are typically roughened mechanically
or etched chemically to provide increased surface area for
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bonding and then treated chemically to provide a stable
corrosion-resistant oxide layer. The surfaces are then thinly
coated with an adhesive bonding primer to promote adhesion and
protect from subsequent corrosion. Structural adhesives are
applied as either a thin film or as a paste. The parts are
joined together and cured either at ambient temperature, in an
oven, or in an autoclave to cure the adhesive and provide a
permanent bond between the components.
Nonstructural adhesives are used to bond materials that are
not critical to the structural integrity of the aerospace vehicle
or component, such as gaskets around windows and carpeting or to
nonstructurally joined components. These adhesives are applied
using tubes, brushes, and spray guns.
2.2.2 Cleaning
Cleaning agents for hand-wipe, flush, and spray equipment
cleaning consist of solvents such as methyl ethyl ketone, methyl
isobutyl ketone, toluene, various solvent blends, or alkaline
materials.
2.2.2.1 Hand-Wipe and Flush Cleaning. Aerospace components
are cleaned frequently during manufacturing to remove
contaminants such as dirt, grease, and oil, and to prepare the
components for the next operation. Cleaning is typically
performed by a hand wiping process using a wide variety of
cleaning solvents. Assemblies and parts with concealed or
inaccessible areas may be flush-cleaned by passing the cleaning
agent over, into, or through the part. The cleaning agent is
then drained from the part and the procedure is repeated as many
times as necessary to ensure the required cleanliness.
2.2.2.2 Spray Gun and Coating Line Cleaning. Spray guns
and coating lines used to apply the various coatings used at
aerospace facilities must be cleaned when switching from one
coating to another and when they are not going to be immediately
reused. Spray guns can be cleaned either manually or with
enclosed spray gun cleaners. Manual cleaning involves
disassembling the gun and placing the parts in a vat containing
an appropriate cleaning solvent. The residual paint is brushed
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or wiped off the parts. After reassembling, the cleaning solvent
may be sprayed through the gun for a final cleaning. Paint
hoses/coating lines are cleaned by passing the cleaning solvent
through the lines until all coating residue is removed.
Enclosed spray gun cleaners are self-contained units that
pump the cleaning solvent through the gun within a closed
chamber. After the cleaning cycle is complete, the guns are
removed from the chamber and typically undergo some manual
cleaning to remove coating residue from areas not exposed to the
cleaning solvent, such as the seals under the atomizing cap.
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3.0 EMISSION CONTROL TECHNIQUES
The principal technique used by the aerospace industry to
control VOC emissions from coating application and cleaning is
product substitution, which eliminates or reduces the generation
of emissions. The emission reduction is obtained using less
energy and producing less waste than using a control device to
achieve the same emission reductions.
The VOC emissions may be controlled by replacing products
containing high concentrations of VOC's with ones that have
reduced or eliminated VOC's. Different aerospace manufacturers
use different processes to produce their product. Therefore,
they typically have different specifications for the coatings and
cleaning solvents used on the components of the end products.
Each individual facility must evaluate the ability of the new
product to maintain standards of quality and performance. In
addition, the potential overall environmental benefit of the
reformulated products must be carefully evaluated.
The following sections describe the available product
substitutions for coatings and cleaning solvents. While
alternative methods, such as control devices (carbon adsorbers,
incinerators, etc.), are occasionally used to reduce emissions,
they do not represent RACT and are, therefore, not discussed
below.
3.1 COATING SUBSTITUTIONS
Waterborne and high solids materials are generally used for
coating substitutions. Specialty coatings typically have
relatively low usage, so reformulation to lower VOC contents does
not produce significant air quality benefits nor is it
economically feasible for the paint suppliers. Paint suppliers
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and the aerospace industry generally have targeted high volume
materials for reformulation efforts. Therefore, lower VOC
formulations are not available for most of the low volume
specialty coating categories.
3.2 EQUIPMENT CHANGES
The aerospace industry has implemented several equipment
changes that directly reduce the level of VOC emissions. While
there are equipment changes that effect emissions from every
process, the three changes predominantly used in the industry are
high transfer efficiency spray guns, spray gun cleaners, and
conventional high transfer efficiency methods. Each of these
equipment changes are discussed below.
3.2.1 High Transfer Efficiency Spray Guns
Emissions from spray coating operations can be reduced
through the use of spraying systems with higher transfer
efficiency. Transfer efficiency, expressed as a percentage, can
be defined as the ratio of coating solids actually applied to the
surface of the component being coated to the amount of solids
released from the spray gun. Spraying systems with a higher
transfer efficiency can coat the same surface area using less
coating. Therefore, the VOC emissions resulting from the use of
this equipment are reduced compared to applying the same coating
with conventional spray equipment. The transfer efficiency
values reported in this section depend on coating sprayed, part
configuration, spray booth air velocity, and other variables.
Most aerospace components are coated using manual spray
equipment utilizing conventional airspray or airless spraying
technology. The following sections discuss two types of high
transfer coating application equipment generally used in the
aerospace industry for the application of primers and topcoats:
high volume, low pressure (HVLP) and electrostatic (use of these
types of high transfer efficiency for specialty coatings is
limited).
3.2.1.1 High volume low pressure spray guns. High volume
low pressure and electrostatic spraying systems are the primary
high efficiency spray methods used by the industry. High volume
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low pressure spray guns use high volumes [10 to 25 standard cubic
feet per minute (scfm)] of low pressure [2 to 10 pounds per
square inch gauge (psig)] air to deliver the paint. The lower
air pressure creates a lower particle speed, resulting in a more
controlled spray pattern with less overspray and bounce back from
the substrate, thus improving transfer efficiency.
High volume low pressure systems have been in use in the
United States for approximately 10 years. In early systems,
turbines were used to supply a high volume of low pressure air to
the spray guns through large hoses. The second generation used
compressed air with an air regulator to maintain the required low
pressure. The third and current generation of HVLP equipment
uses restrictors within the gun to reduce the atomization
pressure to a maximum of 10 psi at the air cap.
One disadvantage of HVLP spray guns is that some very high
solids coatings are difficult to atomize due to their higher
viscosities. However, when a turbine is used, the temperature of
the atomizing air increases which aids in reducing the viscosity
of the coating. Other disadvantages of HVLP spray guns are that
they cannot be used with extension nozzles, and they may slow
production rates because of the low fluid delivery rates.
It is estimated that HVLP can apply approximately 80 percent
of the coating currently used in the aerospace industry,
including primers, waterborne coatings, and both single and two-
component topcoats. A medium commercial/rework facility utilizes
HVLP equipment with high solids paint and has had a reduction of
22-30 percent in coating usage for various aircraft types. The
HVLP technology has proven easy to use and maintain. It also
provides high transfer efficiency and appears to be the preferred
spray technology in the aerospace industry at this time.
Table 3-1 shows the reduction in emissions obtained from the
Section 114 questionnaire responses from various facilities
utilizing high transfer efficiency equipment such as HVLP or
electrostatic equipment, either alone, in conjunction with each
other, or, in one case, HVLP equipment with high solids coatings.
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TABLE 3-1. PERCENT REDUCTION IN COATING EMISSIONS
(PRIMERS AND TOPCOATS) WITH HIGH TRANSFER
EFFICIENCY EQUIPMENT FROM SECTION 114 DATA
Size
Large
Large
Large
Large
Large
Medium
Medium
Medium
Medium
Medium
Medium
Medium
Medium
Medium
Medium
Medium
Medium
Small
Small
Commercial or
military
Military
Military
Military
Commercial
Commercial
Commercial
Military
Military
Commercial
Military
Military
Military
Military
Military
Military
Military
Military
Military
Commercial
Commercial
Commercial
Commercial
Commercial
Commercial
Military
OEM or
rework
OEM
OEM
OEM
OEM
OEM
OEM
OEM
Rework
OEM
OEM
Rework
OEM
OEM
OEM
OEM
OEM
Rework
Rework
OEM
OEM
Rework
Rework
OEM
OEM
OEM
High transfer
equipment
HVLP
HVLP
HVLP
Unspecified
Unspecified
HVLP
HVLP
HVLP and
electrostatic
HVLP and
electrostatic
HVLP
HVLP
Electrostatic
HVLP and
electrostatic
Unspecified
Unspecified
HVLP and
electrostatic
HVLP and high solids
Unspecified
HVLP
% Reduction in emissions
20
20
25
30
18
25
20-40
40
40
40
10
30-40
35-40
30
33
50
22% for large aircraft
25 % for medium aircraft
30% for small aircraft
30
28
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3.2.1.2 Electrostatic spray guns. With electrostatic spray
systems, atomized particles of coating acquire an electric charge
as they pass through a high voltage field at the end of the spray
nozzle. This electric charge causes the particles to be
attracted to the parts being painted, which are electrically
grounded. Although other substrates can be pretreated with
conductive coatings, this technology is primarily used for metal
parts. The electrostatic effect can be utilized in conjunction
with air spray, airless, and air-assisted airless systems to
enhance the transfer efficiencies of these basic technologies.
See Table 3-1 for examples of percent reduction obtained at
various facilities using electrostatic spray guns or
electrostatic spray guns in combination with HVLP spray guns.
3.2.2 Spray Gun Cleaning
Spray guns are typically cleaned at the end of every job, as
well as between color changes. Manual cleaning of spray guns
involves disassembling the gun and placing the parts in a tray
containing an appropriate cleaning solvent. The residual paint
is brushed or wiped off the parts, then cleaning solvent is
sprayed through the gun after it is reassembled. Various methods
are used to minimize the resulting emissions from spray gun
cleaning and are discussed below.
Enclosed system. Enclosed spray gun cleaners are completely
enclosed units that spray the cleaning solvent through and over
the spray gun. The enclosed unit eliminates most of the exposure
of the cleaning solvent to the air, thereby greatly reducing the
VOC emissions from evaporation.
Nonatomized cleaning. Cleaning solvent is placed in the
pressure pot and forced through the gun with the atomizing cap in
place. No atomizing air is to be used. The cleaning solvent
from the spray gun is directed into a vat, drum, or other waste
container that is closed when not in use.
Disassembled spray gun cleaning. Manual cleaning (described
above) with the components cleaned by hand in a vat, which is
only closed when not in use. Alternatively, the components are
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soaked in a vat, which is closed at all times except when
components are being inserted or removed.
Atomizing cleaning. Cleaning solvent is forced through the
spray gun and the resulting atomized spray is directed into a
waste container that is fitted with a device designed to capture
the atomized solvent emissions.
3.2.3 Conventional High Transfer Efficiency Application Methods
Conventional high transfer efficiency application methods
for primers and topcoats include dip, roll, brush, and flow
coating (use of these methods for specialty coatings is limited).
These methods are discussed below.
Dip Coating. With dip coating application, parts are
immersed into a tank of coating. The parts are then removed from
the tank and held over it until the excess coating drips back
into the tank. This method is simple and allows many different
parts to be coated with high transfer efficiency. However, dip
coating is limited to parts that can fit into the dip tank.
Other parts difficult to dip coat could include complex parts
that would trap the coating, allowing unequal coating
thicknesses.
Roll Coating. In roll coating application, a series of
mechanical rollers are used to coat flat surfaces. This method
achieves high efficiency with high rates of application and
automation. However, roll coating is limited to flat parts.
Brush Coating. In brush coating application, brushes and
hand rollers are used to apply the coating manually. This method
is used with operations (e.g., touch-up and detail painting) that
cannot tolerate the overspray associated with spray gun
application. For example, if a facility needs to paint only the
tail section of an airplane, it may be easier to brush coat this
area than to mask the entire plane to protect the rest of the
shell from overspray. This application method typically involves
high labor costs, increased production time, and poor coating
thickness control.
Flow Coating. In flow coating application, the part is
conveyed over a closed sink, and a pumped stream of coating
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gently flows over the surface of the part. The excess coating is
drained into the sink, filtered, and pumped to a holding tank for
reuse. Flow coating is typically limited to flat sheets and
noncritical parts. Coating thickness is difficult to control
using flow coating.
3.3 HAND-WIPE CLEANER SUBSTITUTIONS
Product substitutions for hand-wipe cleaning that are
prevalent in the aerospace industry can be classified as aqueous,
semiaqueous, citrus-based, and reduced vapor pressure. Each
category is discussed below.
3.3.1 Aqueous and Semiaqueous
Aqueous and semiaqueous cleaners contain water as the base
component rather than an organic solvent or mixture of solvents.
Other components may include corrosion inhibitors, alkalinity
builders, and organic surfactants, depending on the desired soil
removal properties. Aqueous and semiaqueous cleaners have been
used in noncritical areas where strict cleanliness requirements
do not have to be met, or where there are no confined spaces that
may trap residues of the cleaner.
The advantages of using aqueous and semiaqueous cleaning
solvents include reduced VOC emissions. Disadvantages are
increased production time due to slower evaporation rates,
possible decreased efficiency, and possible increase in
wastewater treatment requirements. In addition, aqueous cleaners
may not be applicable to all aerospace parts, especially those
components that have small confined spaces where the cleaner
residues cannot be adequately removed.
3.3.2 Citrus-Based
Citrus-based terpenes such as d-limonene are the primary
components in many alternative cleaning solutions. While these
solutions have high VOC contents, their vapor pressure is very
low, leading to reduced evaporation rates. These cleaners have
been found to be effective in some cleaning operations except for
cleaning prior to adhesive bonding. Some disadvantages include
possible worker sensitivity, VOC emissions, lack of rinseability
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in water, and increased production time due to slower evaporation
rates.
3.3.3 Reduced Vapor Pressure
Reduced vapor pressure cleaning solvents have a maximum VOC
composite vapor pressure of 45 millimeters of mercury (mmHg)
at 20°C. Cleaning solvent emissions are reduced because their
lower vapor pressure leads to reduced evaporation rates. These
cleaners are effective in many cleaning operations except for
some limited operations such as cleaning oxygen systems.
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4.0 PRESUMPTIVE RACT REQUIREMENTS
The presumptive RACT requirements for the aerospace
component and vehicle cleaning and coating operations are
described in the following sections. The operations covered by
this CTG shall not be subject to another CTG. The operations and
applications exempted under this CTG shall not be subject to
another CTG. Applicable definitions are included in Appendix A.
These presumptive RACT requirements do not apply to rework
operations performed on antique aerospace vehicles or components,
or to the following activities where cleaning and coating of
aerospace components and vehicles may take place: research and
development, quality control, laboratory testing, and electronic
parts and assemblies (except for cleaning and coating of
completed assemblies). Because of the nature of these
activities, they shall not be regulated by any other CTG.
4.1 SPECIALTY COATINGS
Presumptive RACT for coatings used on aerospace components
and vehicles is based on VOC content. Except as provided in
Sections 4.0 and 4.1, the presumptive RACT for coating VOC
content is the use of coatings with a VOC content less than or
equal to that given in Table 4-1: Specialty Coatings VOC Content
Limits.
Exemptions. The following applications are exempt from the
presumptive RACT coating limits in Table 4-1:
1. Touchup, aerosol, and DOD classified coatings;
2. Coatings used on space vehicles; and
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TABLE 4-1. SPECIALTY COATINGS VOC CONTENT LIMITS (g/L)
Coating type
Limit Coating type
Limit
Ablative Coating 600
Adhesion Promoter 890
Adhesive Bonding Primers:
Cured at 250°F or below 850
Cured above 250°F 1030
Adhesives:
Commercial Interior Adhesive 760
Cyanoacrylate Adhesive 1,020
Fuel Tank Adhesive 620
Nonstructural Adhesive 360
Rocket Motor Bonding Adhesive 890
Rubber-based Adhesive 850
Structural Autoclavable Adhesive 60
Structural Nonautoclavable Adhesive .... 850
Antichafe Coating 660
Chemical Agent-Resistant Coating 550
Clear Coating 720
Commercial Exterior Aerodynamic
Structure Primer 650
Compatible Substrate Primer 780
Corrosion Prevention Compound 710
Cryogenic Flexible Primer 645
Cryoprotective Coating 600
Electric or Radiation-Effect Coating 800
Electrostatic Discharge and Electromagnetic
Interference (EMI) Coating 800
Elevated Temperature Skydrol Resistant
Commercial Primer 740
Epoxy Polyamide Topcoat 660
Fire-Resistant (interior) Coating 800
Flexible Primer 640
Flight-Test Coatings:
Missile or Single Use Aircraft 420
All Other 840
Fuel-Tank Coating 720
High-Temperature Coating 850
Insulation Covering 740
Intermediate Release Coating 750
Lacquer 830
Maskants:
Bonding Maskant 1,230
Critical Use and Line Sealer Maskant . . 1,020
Seal Coat Maskant 1,230
Metallized Epoxy Coating 740
Mold Release 780
Optical Anti-Reflective Coating 750
Part Marking Coating 850
Pretreatment Coating 780
Rain Erosion-Resistant Coating 850
Rocket Motor Nozzle Coating 660
Scale Inhibitor 880
Screen Print Ink 840
Sealants:
Extrudable/Rollable/Brushable Sealant . . . 240
Sprayable Sealant 600
Self-priming Topcoat 420
Silicone Insulation Material 850
Solid Film Lubricant 880
Specialized Function Coating 890
Temporary Protective Coating 320
Thermal Control Coating 800
Wet Fastener Installation Coating 675
Wing Coating 850
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3. Facilities that use separate formulations in volumes of
less than 50 gallons per year, subject to a maximum exemption of
200 gallons for all such formulations applied annually.
4.2 PRIMERS, TOPCOATS, CHEMICAL MILLING MASKANTS
The broad categories of primers, topcoats, and chemical
milling maskants (Type I/II) are not specialty coatings as listed
in Table 4-1 and are regulated for major sources under the
Aerospace NESHAP requiring MACT limits with a compliance date
specified in 40 CFR 63.749(a). These limits may be assumed to
represent RACT limits 1 year after the major sources have met the
MACT limits and, therefore, shall not be effective until 1 year
after the NESHAP compliance date. The requirements do not apply
to facilities that use separate formulations of primers,
topcoats, and chemical milling maskants (Type I/II) in volumes of
less than 50 gallons per year, subject to a maximum exemption of
200 gallons total for such formulations applied annually.
4.3 APPLICATION EQUIPMENT FOR PRIMERS AND TOPCOATS
Presumptive RACT for primer and topcoat application
equipment used on aerospace components and vehicles is based on
current practices and requirements in some States. Except as
provided in Section 4.3 and Subsection 4.3.1, the presumptive
RACT for primer and topcoat application equipment is the use of
one or more of the following application techniques: flow/
curtain coat; dip coat; roll coating; brush coating; cotton-
tipped swab application; electrodeposition (DIP) coating; high
volume low pressure (HVLP) spraying; electrostatic spray; or
other coating application methods that achieve emission
reductions equivalent to HVLP or electrostatic spray application
methods.
4.3.1 Exemptions
The following situations are exempt from the presumptive
RACT application techniques described in Section 4.3:
1. Any situation that normally requires the use of an
airbrush or an extension on the spray gun to properly reach
limited access spaces;
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2. The application of specialty coatings;
3. The application of coatings that contain fillers that
adversely affect atomization with HVLP spray guns and that the
permitting agency has determined cannot be applied by any of the
application methods specified in Section 4.3;
4. The application of coatings that normally have a dried
film thickness of less than 0.0013 centimeter (0.0005 in.) and
that the permitting agency has determined cannot be applied by
any of the application methods specified in Section 4.3;
5. The use of airbrush application methods for stenciling,
lettering, and other identification markings;
6. The use of hand-held spray can application methods; and
7. Touch-up and repair operations.
4.3.2 Timing (Schedule) of Compliance
The application techniques identified as presumptive RACT
are regulated for major sources under the Aerospace NESHAP
requiring MACT application equipment with a compliance date
specified in 40 CFR 63.749(a). These equipment requirements may
be assumed to represent RACT requirements 1 year after the major
sources have met the RACT equipment requirements and, therefore,
shall not be effective until 1 year after the NESHAP compliance
date.
4.4 CLEANING OPERATIONS
For solvent cleaning operations, this guidance departs from
the standard presumptive RACT requirement to incorporate MACT
level controls. Therefore, the requirements of Section 4.2 shall
not become effective prior to the Aerospace NESHAP compliance
date as specified in 40 CFR 63.749(a). The MACT for solvent
cleaning is based on work practices and cleaning solvent
composition. Except as provided in Section 4.0 and
Subsection 4.2, MACT (and RACT) for certain activities is
described below.
4.4.1 Housekeeping
All fresh and used cleaning solvents, except semiaqueous
cleaning solvents, used in solvent cleaning operations shall be
stored in nonabsorbent, nonleaking containers that shall be kept
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closed at all times except when filling or emptying. It is
recommended that cloth and paper, or other absorbent applicators,
moistened with cleaning solvents be stored in closed,
nonabsorbent, nonleaking containers. Cotton-tipped swabs used
for very small cleaning operations are exempt. In addition, the
owner or operator must implement handling and transfer procedures
to minimize spills during filling and transferring the cleaning
solvent to or from enclosed systems, vats, waste containers, and
other cleaning operation equipment that hold or store fresh or
used cleaning solvents. The above requirements are known
collectively as housekeeping measures. Aqueous cleaning solvents
are excluded from these housekeeping requirements.
4.4.2 Hand-Wipe Cleaning
Hand-wipe cleaning operations require the use of cleaning
solvents which are aqueous or have a VOC composite vapor pressure
less than or equal to 45 millimeters of mercury (mm Hg) at 20°C.
Exemptions
The following cleaning operations would be exempt from the
cleaning solvent composition and vapor pressure requirements
stated in Section 4.4.2:
1. Cleaning during the manufacture, assembly,
installation, or testing of components of breathing oxygen
systems that are exposed to the breathing oxygen;
2. Cleaning during the manufacture, assembly,
installation, or testing of parts, subassemblies, or assemblies
that are exposed to strong oxidizers or reducers (e.g., nitrogen
tetroxide, liquid oxygen, hydrazine);
3. Cleaning and surface activation prior to adhesive
bonding;
4. Cleaning of electronics and assemblies containing
electronics;
5. Cleaning of aircraft and ground support equipment fluid
systems that are exposed to the fluid, including air-to-air heat
exchangers and hydraulic fluid systems;
6. Cleaning of fuel cells, fuel tanks, and confined
spaces;
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7. Surface cleaning of solar cells, coated optics, and
thermal control surfaces;
8. Cleaning during fabrication, assembly, installation,
and maintenance of upholstery, curtains, carpet, and other
textile materials used on the interior of the aircraft;
9. Cleaning of metallic and nonmetallic materials used in
honeycomb cores during the manufacture of these cores, and
cleaning of the completed cores used in the manufacture of
aerospace vehicles or components;
10. Cleaning of aircraft transparencies, polycarbonates, or
glass substrates;
11. Cleaning and solvent usage associated with research and
development, quality control, or laboratory testing;
12. Cleaning operations, using nonflammable liquids,
conducted within 5 feet of energized electrical systems.
Energized electrical systems means any AC or DC electrical
circuit on an assembled aircraft once electrical power is
connected, including interior passenger and cargo areas, wheel
wells, and tail sections; and
13. Cleaning operations identified in any Essential Use
Waiver application that have been reviewed and approved by the
EPA and the voting parties of the International Montreal Protocol
committee.
4.4.3 Flush Cleaning
For cleaning solvents used in the flush cleaning of
aerospace parts, assemblies, and coating unit components, the
used cleaning solvent (except for semiaqueous cleaning solvents)
must be emptied into an enclosed container or collection system
that is kept closed when not in use or captured on wipers and
disposed of in accordance with Section 4.4.1. Aqueous cleaning
solvents are excluded from these flush cleaning requirements.
4.4.4 Sprav Gun Cleaning
All spray guns must be cleaned by one or more of the
following methods:
1. Enclosed spray gun cleaning system that is kept closed
when not in use, provided that leaks from enclosed spray gun
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cleaners are repaired within 14 days from when the leak is first
discovered. If the leak is not repaired by the 15th day after
detection, the cleaning solvent shall be removed and the enclosed
cleaner shall be shut down until the leak is repaired or its use
is permanently discontinued;
2. Unatomized discharge of cleaning solvent into a waste
container that is kept closed when not in use;
3. Disassembled spray gun that is cleaned in a vat and kept
closed when not in use; or
4. Atomized spray into a waste container that is fitted
with a device designed to capture atomized cleaning solvent
emissions.
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5.0 GUIDANCE TO STATE ENFORCEMENT AGENCIES
This chapter presents information for air quality management
agencies to consider in developing an enforceable rule limiting
VOC emissions from coating and solvent cleaning operations at
aerospace manufacturing and rework facilities. The State or
other implementing agency can exercise its prerogative to
consider other options provided that they meet the objectives
prescribed in this chapter.
This guidance is for instructional purposes only and, as
such, is not binding. In the development of a State or local
aerospace manufacturing and rework operations rule, the State or
other enforcement agency should consider all information
presented in the CTG and the promulgated NESHAP along with
additional information about specific sources to which the rule
will apply. The reasonably available control technology (RACT)
rule, however, should address all the factors listed in this
chapter and in Section 4 to ensure that the rule has reasonable
provisions for demonstrating compliance and is enforceable. A
model rule which contains all these requirements is provided in
Appendix B. The model rule is guidance only and the State or
local agency has the flexibility to adopt alternative measures,
including market-based incentive programs, provided they meet EPA
enforceability criteria.
5.1 DEFINITIONS
The RACT rule should accurately describe the types of
sources that would be affected and clearly define terms used to
describe the industry or applicable control methods. Example
definitions of pertinent terms are presented in Appendix A for
reference by the State or local agency.
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5.2 APPLICABILITY
The recommended RACT described in this document applies to
the manufacture of aerospace vehicles and components as well as
the rework or repair of these aerospace products. (See
Section 2.) This guidance has been developed for affected
sources in areas of moderate, serious, or severe nonattainment
that have the potential to emit greater than or equal to 25 tons
per year of VOC's. The guidance is intended to apply to affected
sources in extreme areas, however, if potential VOC emissions are
greater than or equal to 10 tons per year. The State or local
agency has the flexibility to apply RACT as deemed necessary.
For example, an agency may apply RACT to all sources that have
actual emissions at 50 percent of these thresholds.
5.3 COMPLIANCE, MONITORING, RECORDKEEPING & REPORTING PROVISIONS
The State or local agency is responsible for ensuring that
appropriate requirements for compliance determination (testing),
monitoring, recordkeeping and reporting are incorporated into its
RACT rule. These requirements must meet two objectives: (1) the
agency's need to demonstrate VOC emission reductions and
(2) EPA's criteria for enforceability. Because source types,
compliance methods, and agency requirements may vary
substantially across the nation, specific provisions for
compliance determination (testing), monitoring, recordkeeping and
reporting are not included in this CTG.
However, for a State's RACT rules to be enforceable, they
must definitively set forth recordkeeping, monitoring, and
compliance determination (testing) requirements appropriate to
the type of source(s) being regulated and sufficient to allow
determinations whether the source(s) are in compliance.
Therefore, EPA's Model Rule, which accompanies this CTG, contains
suggested recordkeeping, testing, and monitoring provisions that
EPA believes are sufficient to enable EPA and the States to
determine compliance with the RACT requirements of the Model
Rule. The State or other implementing agency can exercise its
prerogative to consider various recordkeeping, testing, and
monitoring requirements provided they meet the objectives
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prescribed in this CTG. This guidance is for instructional
purposes only and, as such, is not binding.
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APPENDIX A. DEFINITIONS
Terms used in this CTG and the Model Rule in Appendix B are
defined in the Clean Air Act (Act), or in this section as
follows:
Ablative coating means a coating that chars when exposed to
open flame or extreme temperatures, as would occur during the
failure of an engine casing or during aerodynamic heating. The
ablative char surface serves as an insulative barrier, protecting
adjacent components from the heat or open flame.
Adhesion promoter means a very thin coating applied to a
substrate to promote wetting, and form a chemical bond with the
subsequently applied material.
Adhesive bonding primer means a primer applied in a thin
film to aerospace components for the purpose of corrosion
inhibition and increased adhesive bond strength by attachment.
There are two categories of adhesive bonding primers: primers
with a design cure at 250°F or below and primers with a design
cure above 250°F.
Aerosol coating means a hand-held, pressurized,
nonrefillable container that expels an adhesive or a coating in a
finely divided spray when a valve on the container is depressed.
Aerospace vehicle or component means any fabricated part,
processed part, assembly of parts, or completed unit, with the
exception of electronic components, of any aircraft including but
not limited to airplanes, helicopters, missiles, rockets, and
space vehicles.
Aircraft fluid systems means those systems that handle
hydraulic fluids, fuel, cooling fluids, or oils.
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Aircraft transparency means the aircraft windshield, canopy,
passenger windows, lenses and other components which are
constructed of transparent materials.
Antichafe coating means a coating applied to areas of moving
aerospace components that may rub during normal operations or
installation. -
Antique aerospace vehicle or component means an antique
aircraft, as defined by 14 CFR Part 45, or components thereof.
An antique aerospace vehicle would not routinely be in commercial
or military service in the capacity for which it was designed.
Aqueous cleaning solvent means a solvent in which water is
at least 80 percent of the solvent as applied.
Bonding maskant means a temporary coating used to protect
selected areas of aerospace parts from strong acid or alkaline
solutions during processing for bonding.
Chemical agent-resistant coating (CARC) means an exterior
topcoat designed to withstand exposure to chemical warfare agents
or the decontaminants used on these agents.
Chemical milling maskant means a coating that is applied
directly to aluminum components to protect surface areas when
chemical milling the component with a Type I or II etchant. This
does not include bonding maskants, line sealers, and critical use
and seal coat maskants. Additionally, maskants that must be used
on an individual part or subassembly with a combination of Type I
or II etchants and any of the above types of maskants (e.g.,
bonding, line sealers, and critical use and seal coat) are not
included. Maskants that are defined as specialty coatings are
not included under this definition.
Cleaning operation means collectively spray-gun, hand-wipe,
and flush cleaning operations.
Cleaning solvent means a liquid material used for hand-wipe,
spray gun, or flush cleaning. This definition does not include
solutions that contain no VOC.
Clear coating means a transparent coating usually applied
over a colored opaque coating, metallic substrate, or placard to
give improved gloss and protection to the color coat. In some
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cases, a clearcoat refers to any transparent coating without
regard to substrate.
Closed-cycle depainting system means a dust free, automated
process that removes permanent coating in small sections at a
time, and maintains a continuous vacuum around the area(s) being
depainted to capture emissions.
Coating means a material that is applied to the surface of
an aerospace vehicle or component to form a decorative or
functional solid film, or the solid film itself.
Coating operation means using a spray booth, tank, or other
enclosure or any area, such as a hangar, for applying a single
type of coating (e.g., primer); using the same spray booth for
applying another type of coating (e.g., topcoat) constitutes a
separate coating operation for which compliance determinations
are performed separately.
Coating unit means a series of one or more coating
applicators and any associated drying area and/or oven wherein a
coating is applied, dried, and/or cured. A coating unit ends at
the point where the coating is dried or cured, or prior to any
subsequent application of a different coating. It is not
necessary to have an oven or flashoff area to be included in this
definition.
Commercial exterior aerodynamic structure primer means a
primer used on aerodynamic components and structures that
protrude from the fuselage, such as wings and attached
components, control surfaces, horizontal stabilizers, vertical
fins, wing-to-body fairings, antennae, and landing gear and
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doors, for the purpose of extended corrosion protection and
enhanced adhesion.
Commercial interior adhesive means materials used in the
bonding of passenger cabin interior components. These components
must meet the FAA fireworthiness requirements.
Compatible Substrate Primer means either compatible Epoxy
Primer or Adhesive Primer. Compatible Epoxy Primer is primer
that is compatible with the filled elastomeric coating and is
epoxy based. The compatible substrate primer is an epoxy-
polyamide primer used to promote adhesion of elastomeric coatings
such as impact- resistant coatings. Adhesive Primer is a coating
that (1) inhibits corrosion and serves as a primer applied to
bare metal surfaces or prior to adhesive application, or (2) is
applied to surfaces that can be expected to contain fuel. Fuel
tank coatings are excluded from this category.
Confined space means a space that (1) is large enough and so
configured that an employee can bodily enter and perform assigned
work; (2) has limited or restricted means for entry or exit (for
example, fuel tanks, fuel vessels, and other spaces that have
limited means of entry); and (3) is not suitable for continuous
employee occupancy.
Corrosion prevention system means a coating system that
provides corrosion protection by displacing water and penetrating
mating surfaces, forming a protective barrier between the metal
surface and moisture. Coatings containing oils or waxes are
excluded from this category.
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Critical use and line sealer maskant means a temporary
coating, not covered under other maskant categories, used to
protect selected areas of aerospace parts from strong acid or
alkaline solutions such as those used in anodizing, plating,
chemical milling and processing of magnesium, titanium, or high
strength steel, high precision aluminum chemical milling of deep
cuts, and aluminum chemical milling of complex shapes. Materials
used for repairs or to bridge gaps left by scribing operations
(i.e., line sealer) are also included in this category.
Cryogenic flexible primer means a primer designed to provide
corrosion resistance, flexibility, and adhesion of subsequent
coating systems when exposed to loads up to and surpassing the
yield point of the substrate at cryogenic temperatures (-275°F
and below).
Cryoprotective coating means a coating that insulates
cryogenic or subcooled surfaces to limit propellant boil-off,
maintain structural integrity of metallic structures during
ascent or re-entry, and prevent ice formation.
Cyanoacrylate adhesive means a fast-setting, single
component adhesive that cures at room temperature. Also known as
"super glue."
Electric or radiation-effect coating means a coating or
coating system engineered to interact, through absorption or
reflection, with specific regions of the electromagnetic energy
spectrum, such as the ultraviolet, visible, infrared, or
microwave regions. Uses include, but are not limited to,
lightning strike protection, electromagnetic pulse (BMP)
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protection, and radar avoidance. Coatings that have been
designated "classified" by the Department of Defense are exempt.
Electrostatic discharge and electromagnetic interference
(EMI) coating means a coating applied to space vehicles,
missiles, aircraft radomes, and helicopter blades to disperse
static energy or reduce electromagnetic interference.
Elevated temperature Skydrol resistant commercial primer
means a primer applied primarily to commercial aircraft (or
commercial aircraft adapted for military use) that must withstand
immersion in phosphate-ester (PE) hydraulic fluid (Skydrol 500b
or equivalent) at the elevated temperature of 150°F for
1,000 hours.
Epoxy polyamide topcoat means a coating used where harder
films are required or in some areas where engraving is
accomplished in camouflage colors.
Exempt solvent means a specified organic compounds that have
been determined by the EPA to have negligible photochemical
reactivity and are listed in 40 CFR 51.100.
Fire-resistant (interior) coating means for civilian
aircraft, fire-resistant interior coatings are used on passenger
cabin interior parts that are subject to the FAA fireworthiness
requirements. For military aircraft, fire-resistant interior
coatings are used on parts that are subject to the flammability
requirements of MIL-STD-1630A and MIL-A-87721. For space
applications, these coatings are used on parts that are subject
to the flammability requirements of SE-R-0006 and SSP 30233.
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Flexible primer means a primer that meets flexibility
requirements such as those needed for adhesive bond primed
fastener heads or on surfaces expected to contain fuel. The
flexible coating is required because it provides a compatible,
flexible substrate over bonded sheet rubber and rubber-type
coatings as well as a flexible bridge between the fasteners,
skin, and skin-to-skin joints on outer aircraft skins. This
flexible bridge allows more topcoat flexibility around fasteners
and decreases the chance of the topcoat cracking around the
fasteners. The result is better corrosion resistance.
Flight test coating means a coating applied to aircraft
other than missiles or single-use aircraft prior to flight
testing to protect the aircraft from corrosion and to provide
required marking during flight test evaluation.
Flush cleaning means removal of contaminants such as dirt,
grease, oil, and coatings from an aerospace vehicle or component
or coating equipment by passing solvent over, into, or through
the item being cleaned. The solvent simply may be poured into
the item being cleaned and then drained or assisted by air or
hydraulic pressure or by pumping. Hand-wipe cleaning operations
where wiping, scrubbing, mopping, or other hand action are used
are not included.
Fuel tank adhesive means an adhesive used to bond components
exposed to fuel and must be compatible with fuel tank coatings.
Fuel tank coating means a coating applied to fuel tank
components for the purpose of corrosion and/or bacterial growth
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inhibition and to assure sealant adhesion in extreme
environmental conditions.
Grains per liter VOC means a weight of VOC per combined
volume of VOC and coating solids, less water and exempt
compounds, and can be calculated by the following equation:
W_ - Ww - Wes
grains per liter = —
Vs - Vw - Ves
Ws = weight of volatile organic compounds in grams
Ww = weight of water in grams
Wes = weight of exempt compounds in grams
V_ = volume of material in liters
o
Vw = volume of water in liters
Ves = volume of exempt compounds in liters
Hand-wipe cleaning operation means removing contaminants
such as dirt, grease, oil, and coatings from an aerospace vehicle
or component-by physically rubbing it with a material such as a
rag, paper, or cotton swab that has been moistened with a
cleaning solvent.
High temperature coating means a coating designed to
withstand temperatures of more than 350°F.
High volume low pressure (HVLP) spray equipment means spray
equipment that is used to apply coating by means of a spray gun
that operates at 10.0 psig of atomizing air pressure or less at
the air cap.
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Insulation covering means material that is applied to foam
insulation to protect the insulation from mechanical or
environmental damage.
Intermediate release coating means a thin coating applied
beneath topcoats to assist in removing the topcoat in depainting
operations and generally to allow the use of less hazardous
depainting methods.
Lacquer means a clear or pigmented coating formulated with a
nitrocellulose or synthetic resin to dry by evaporation without a
chemical reaction. Lacquers are resoluble in their original
solvent.
Leak means any visible leakage, including misting and
clouding.
Limited access space means internal surfaces or passages of
an aerospace vehicle or component that cannot be reached without
the aid of an airbrush or a spray gun extension for the
application of coatings.
Metalized epoxy coating means a coating that contains
relatively large quantities of metallic pigmentation for
appearance and/or added protection.
Mold release means a coating applied to a mold surface to
prevent the molded piece from sticking to the mold as it is
removed.
Nonstructural adhesive means an adhesive that bonds nonload
bearing aerospace components in noncritical applications and is
not covered in any other specialty adhesive categories.
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Operating parameter value means a minimum or maximum value
established for a control equipment or process parameter that, if
achieved by itself or in combination with one or more other
operating parameter values, determines that an owner or operator
has complied with an applicable emission limitation.
Optical antireflection coating means a coating with a low
reflectance in the infrared and visible wavelength ranges that is
used for antireflection on or near optical and laser hardware.
Part marking coating means coatings or inks used to make
identifying markings on materials, components, and/or assemblies.
These markings may be either permanent or temporary.
Pretreatment coating means an organic coating that contains
at least 0.5 percent acids by weight and is applied directly to
metal surfaces to provide surface etching, corrosion resistance,
adhesion, and ease of stripping.
Primer means the first layer and any subsequent layers of
identically formulated coating applied to the surface of an
aerospace vehicle or component. Primers are typically used for
corrosion prevention, protection from the environment, functional
fluid resistance, and adhesion of subsequent coatings. Primers
that are defined as specialty coatings are not included under
this definition.
Radome means the nonmetallic protective housing for.
electromagnetic transmitters and receivers (e.g., radar,
electronic countermeasures, etc.).
Rain erosion-resistant coating means- a coating or coating
system used to protect the leading edges of parts such as flaps,
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stabilizers, radomes, engine inlet nacelles, etc. against erosion
caused by rain impact during flight.
Research and Development means an operation whose primary
purpose is for research and development of new processes and
products and that is conducted under the close supervision of
technically trained personnel and is not involved in the
manufacture of final or intermediate products for commercial
purposes, except in a de minimis manner.
Rocket motor bonding adhesive means an adhesive used in
rocket motor bonding applications.
Rocket motor nozzle coating means a catalyzed epoxy coating
system used in elevated temperature applications on rocket motor
nozzles.
Rubber-based adhesive means a quick setting contact cements
that provide a strong, yet flexible bond between two mating
surfaces that may be of dissimilar materials.
Scale inhibitor means a coating that is applied to the
surface of a part prior to thermal processing to inhibit the
formation of scale.
Screen print ink means a inks used in screen printing
processes during fabrication of decorative laminates and decals.
Sealant means a material used to prevent the intrusion of
water, fuel, air, or other liquids or solids from certain areas
of aerospace vehicles or components. There are two categories of
sealants: extrudable/rollable/brushable sealants and sprayable
sealants.
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Seal coat maskant means an overcoat applied over a maskant
to improve abrasion and chemical resistance during production
operations.
Self-priming topcoat means a topcoat that is applied
directly to an uncoated aerospace vehicle or component for
purposes of corrosion prevention, environmental protection, and
functional fluid resistance. More than one layer of identical
coating formulation may be applied to the vehicle or component.
The coating is not subsequently topcoated with any other product
formulation.
Semiagueous cleaning solvent means a solution in which water
is a primary ingredient (.>60 percent of the solvent solution as
applied must be water.)
Silicone insulation material means an insulating material
applied to exterior metal surfaces for protection from high
temperatures caused by atmospheric friction or engine exhaust.
These materials differ from ablative coatings in that they are
not "sacrificial."
Solids means the nonvolatile portion of the coating that
after drying makes up the dry film.
Solid film lubricant means a very thin coating consisting
of a binder system containing as its chief pigment material one
or more of the following: molybdenum, graphite, polytetrafluoro-
ethylene (PTFE), or other solids that act as a dry lubricant
between faying surfaces.
Space vehicle means a man-made device, either manned or
unmanned, designed for operation beyond earth's atmosphere. This
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definition includes integral equipment such as models, mock-ups,
prototypes, molds, jigs, tooling, hardware jackets, and test
coupons. Also included is auxiliary equipment associated with
test, transport, and storage, that through contamination can
compromise the space vehicle performance.
Specialty coating means a coating that, even though it meets
the definition of a primer, topcoat, or self-priming topcoat, has
additional performance criteria beyond those of primers,
topcoats, and self-priming topcoats for specific applications.
These performance criteria may include, but are not limited to,
temperature or fire resistance, substrate compatibility,
antireflection, temporary protection or marking, sealing,
adhesively joining substrates, or enhanced corrosion protection.
Specialized function coating means a coating that fulfills
extremely specific engineering requirements that are limited in
application and are characterized by low volume usage. This
category excludes coatings covered in other Specialty Coating
categories.
Spray gun means a device that atomizes a coating or other
material and projects the particulates or other material onto a
substrate.
Structural autoclavable adhesive means an adhesive used to
bond load carrying aerospace components that is cured by heat and
pressure in an autoclave.
Structural nonautoclavable adhesive means an adhesive cured
under ambient conditions that is used to bond load carrying
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aerospace components or other critical functions, such as
nonstructural bonding in the proximity of engines.
Surface preparation means the removal of contaminants from
the surface of an aerospace vehicle or component or the
activation or reactivation of the surface in preparation for the
application of a coating.
Temporary protective coating means a coating applied to
provide scratch or corrosion protection during manufacturing,
storage, or transportation. Two types include peelable
protective coatings and alkaline removable coatings. These
materials are not intended to protect against strong acid or
alkaline solutions. Coatings that provide this type of
protection from chemical processing are not included in this
category.
Thermal control coating means a coatings formulated with
specific thermal conductive or radiative properties to permit
temperature control of the substrate.
Topcoat means a coating that is applied over a primer on an
aerospace vehicle or component for appearance, identification,
camouflage, or protection. Topcoats that are defined as
specialty coatings are not included under this definition.
Touch-up and repair operation means that portion of the
coating operation that is the incidental application of coating
used to cover minor imperfections in the coating finish or to
achieve complete coverage. This definition includes out-of-
sequence or out-of-cycle coating.
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Volatile organic compound (VOC) means any compound defined
as VOC in 40 CFR 51.100. This includes any organic compound
other than those determined by the EPA to be an exempt solvent.
For purposes of determining compliance with emission limits, VOC
will be measured by the approved test methods. Where such a
method also inadvertently measures compounds that are exempt
solvent, an owner or operator may exclude these exempt solvents
when determining compliance with an emission standard.
VOC composite vapor pressure means the sum of the partial
pressures of the compounds defined as VOC's and is determined by
the following calculation:
wi
— x VP,
MWi
MWW MW0
W^ = Weight of the "i"th VOC compound, grams.
Ww = Weight of water, grams.
We = Weight of non-HAP, nonVOC compound, grams.
MW^ = Molecular weight of the "i"th VOC compound, g/g-mole.
MWW = Molecular weight of water, g/g-mole.
MWe = Molecular weight of exempt compound, g/g-mole.
PPC = VOC composite partial pressure at 20°, mm Hg.
VP^ = Vapor pressure of the "i"th VOC compound at 20°, mm Hg,
Waterborne (water-reducible) coating means a coating which
contains more than 5 percent water by weight as applied in its
volatile fraction.
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Wet fastener installation coating means a primer or sealant
applied by dipping, brushing, or daubing to fasteners that are
installed before the coating is cured.
Wing coating means a corrosion-resistant topcoat that is
resilient enough to withstand the flexing of the wings.
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APPENDIX B. AEROSPACE MANUFACTURING AND REWORK
OPERATIONS MODEL RULE
B.1 APPLICABILITY
(a) Provisions of this Rule
(1) Except as noted in (a)(2) and (a)(3), this rule applies
to the manufacture or rework of commercial, civil, or military
aerospace vehicles or components at facilities located in severe,
serious, and moderate ozone nonattainment areas that have the
potential to emit 25 tons per year of VOC's or more or are
located in extreme nonattainment areas and have potential to emit
10 tons per year or more.
(2) This rule does not apply to the following activities
where cleaning and coating of aerospace components and vehicles
may take place: research and development, quality control,
laboratory testing, and electronic parts and assemblies (except
for cleaning and coating of completed assemblies). Because of
the nature of these activities, they shall not be regulated by
any other CTG.
(3) This rule does not apply to rework operations performed
on antique aerospace vehicles or components.
B.2 DEFINITIONS
For the purpose of this rule the definitions listed in
Appendix A shall apply.
B.3 REQUIREMENTS
(a) VOC content of coatings.
(1) A person shall not apply to aerospace vehicles or
components any specialty coatings, including any VOC-containing
materials added to the original coating supplied by the
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manufacturer, that contain VOC's in excess of the limits
specified below:
(2) The following coating applications are exempt from the
VOC content limits listed in paragraph (B.3)(a)(1):
(i) Touchup, aerosol, and DoD "classified" coatings
(ii) Coating of space vehicles
(iii) Facilities that use separate formulations in volumes
of less than 50 gallons per year subject to a maximum exemption
of 200 gallons total for such formulations applied annually.
(3) Primers, Topcoats, Chemical Milling Maskants. The
broad categories of primers, topcoats, and chemical milling
maskants (Type I/II) are not specialty coatings as listed in the
table in (B.3)(a)(1) and are regulated for major sources under
the Aerospace NESHAP requiring MACT limits with a compliance date
specified in 40 CFR 63.749(a). These limits may be assumed to
represent RACT limits 1 year after the major sources have met the
MACT limits and, therefore, shall not be effective until 1 year
after the NESHAP compliance date. The requirements do not apply
to facilities that use separate formulations of primers,
topcoats, and chemical milling maskants (Type I/II) in volumes of
less than 50 gallons per year, subject to a maximum exemption of
200-gallons total for such formulations applied annually.
(b) Application equipment.
(1) A person shall use one or more of the following
application techniques in applying any primer or topcoat to
aerospace vehicles or components: flow/curtain coat; dip coat;
roll coating; brush coating; cotton-tipped swab application;
electrodeposition (DIP) coating; high volume low pressure (HVLP)
spraying; electrostatic spray; or other coating application
methods that achieve emission reductions equivalent to HVLP or
electrostatic spray application methods.
(2) The following situations are exempt from application
equipment requirements listed in paragraph (B.3)(b)(1):
(i) Any situation that normally requires the use of an
airbrush or an extension on the spray gun to properly reach
limited access spaces;
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VOC CONTENT LIMITS FOR SPECIALTY COATINGS (g/L)
Coating type
Limit Coating type
Limit
Ablative Coating
Adhesion Promoter
Adhesive Bonding Primers:
Cured at 250°F or below
Cured above 250°F
Adhesives:
Commercial Interior Adhesive
Cyanoacrylate Adhesive
Fuel Tank Adhesive
Nonstructural Adhesive
Rocket Motor Bonding Adhesive
Rubber-based Adhesive
Structural Autoclavable Adhesive
Structural Nonautoclavable Adhesive . . .
Antichafe Coating
Chemical Agent-Resistant Coating
Clear Coating
Commercial Exterior Aerodynamic
Structure Primer
Compatible Substrate Primer •. . . .
Corrosion Prevention Compound
Cryogenic Flexible Primer
Cryoprotective Coating
Electric or Radiation-Effect Coating
Electrostatic Discharge and Electromagnetic
Interference (EMI) Coating
Elevated Temperature Skydrol Resistant
Commercial Primer
Epoxy Polyamide Topcoat
Fire-Resistant (interior) Coating
Flexible Primer
. 600 Flight-Test Coatings:
. 890 Missile or Single Use Aircraft
All Other
. 850 Fuel-Tank Coating
1030 High-Temperature Coating
Insulation Covering
. 760 Intermediate Release Coating
1,020 Lacquer
. 620 Maskants:
. 360 Bonding Maskant
. 890 Critical Use and Line Sealer Maskant
. 850 Seal Coat Maskant
. . 60 Metallized Epoxy Coating
. 850 Mold Release
. 660 Optical Anti-Reflective Coating
, 550 Part Marking Coating
. 720 Pretreatment Coating
Rain Erosion-Resistant Coating
. 650 Rocket Motor Nozzle Coating
, 780 Scale Inhibitor
, 710 Screen Print Ink
645 Sealants:
. 600 Extrudable/Rollable/Brushable Sealant
800 Sprayable Sealant
Self-priming Topcoat
800 Silicone Insulation Material
Solid Film Lubricant
740 Specialized Function Coating
660 Temporary Protective Coating
800 Thermal Control Coating
640 Wet Fastener Installation Coating ....
Wing Coating
. 420
. 840
. 720
. 850
. 740
. 750
. 830
1,230
1,020
1,230
. 740
. 780
. 750
. 850
. 780
. 850
. 660
. 880
. 840
. 240
. 600
. 420
. 850
. 880
. 890
. 320
. 800
. 675
. 850
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(ii) The application of specialty coatings;
(iii) The application of coatings that contain fillers that
adversely affect atomization with HVLP spray guns and that the
permitting agency has determined cannot be applied by any of the
application methods specified in Section (B.3)(b)(1);
(iv) The application of coatings that normally have a dried
film thickness of less than 0.0013 centimeter (0.0005 in.) and
that the permitting agency has determined cannot be applied by
any of the application methods specified in Section (B.3)(b)(1);
(v) The use of airbrush application methods for stenciling,
lettering, and other identification markings;
(vi) The use of hand-held spray can application methods;
and
(vii) Touch-up and repair operations.
(3) The application techniques listed in
paragraph (B.3)(b)(1) are regulated for major sources under the
Aerospace NESHAP requiring MACT application equipment with a
compliance date specified in 40 CFR 63,749 (a). These equipment
requirements may be assumed to represent RACT requirements 1 year
after the major sources have met the MACT equipment requirements
and, therefore, shall not be effective until 1 year after the
NESHAP compliance date.•
(c) Solvent cleaning. The following requirements apply to
solvent cleaning operations and shall not be effective until the
Aerospace NESHAP compliance date specified in 40 CFR 63.749(a):
(1) Hand-wipe cleaning. Cleaning solvents used in hand-
wipe cleaning operations shall:
(i) Meet the definition of aqueous cleaning solvent in
Appendix A, or
(ii) Have a VOC composite vapor pressure less than or equal
to 45 millimeters of mercury (mm Hg) at 20°C.
(2) The following solvent cleaning operations are exempt
from the requirements in paragraph (B.3)(c)(1):
(i) Cleaning during the manufacture, assembly,
installation, maintenance, or testing of components of breathing
oxygen systems that are exposed to the breathing oxygen;
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(ii) Cleaning during the manufacture, assembly,
installation, maitenance, or testing of parts, subassemblies, or
assemblies that are exposed to strong oxidizers or reducers
(e.g., nitrogen tetroxide, liquid oxygen, hydrazine);
(iii) Cleaning and surface activation prior to adhesive
bonding;
(iv) Cleaning of electronics parts and assemblies
containing electronics parts;
(v) Cleaning of aircraft and ground support equipment fluid
systems that are exposed to the fluid, including air-to-air heat
exchangers and hydraulic fluid systems;
(vi) Cleaning of fuel cells, fuel tanks, and confined
spaces;
(vii) Surface cleaning of solar cells, coated optics, and
thermal control surfaces;
(viii) Cleaning during fabrication, assembly, installation,
and maintenance of upholstery, curtains, carpet, and other
textile materials used on the interior of the aircraft;
(ix) Cleaning of metallic and nonmetallic materials used in
honeycomb cores during the manufacture or maintenance of these
cores, and cleaning of the completed cores used in the
manufacture of aerospace vehicles or components;
(x) Cleaning of aircraft transparencies, polycarbonate, or
glass substrates;
(xi) Cleaning and solvent usage associated with research
and development, quality control, or laboratory testing;
(xii) Cleaning operations, using nonflammable liquids,
conducted within 5 feet of energized electrical systems.
Energized electrical systems means any AC or DC electrical
circuit on an assembled aircraft once electrical power is
connected, including interior passenger and cargo areas, wheel
wells and tail sections; and,
(xiii) Cleaning operations identified in an Essential Use
Waiver which has been reviewed and approved by the U. S. EPA and
the voting parties of the International Montreal Protocol
Committee [sections 604(d)(l) and (g}(2) of the Act].
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(3) Flush cleaning. For cleaning solvents used in the
flush cleaning of parts, assemblies, and coating unit components,
the used cleaning solvent (except for semiagueous cleaning
solvents) must be emptied into an enclosed container or
collection system that is kept closed when not in use or captured
with wipers provided they comply with the housekeeping
requirements of (B.3)(c)(5). Aqueous cleaning solvents are
exempt from these requirements.
(4) Spray gun cleaning. All spray guns must be cleaned by
one or more of the following methods:
(i) Enclosed spray gun cleaning system provided that it is
kept closed when not in use and leaks are repaired within 14 days
from when the leak is first discovered. If the leak is not
repaired by the 15th day after detection, the solvent shall be
removed and the enclosed cleaner shall be shut down until the
leak is repaired or its use is permanently discontinued,
(ii) Unatomized discharge of solvent into a waste container
that is kept closed when not in use,
(iii) Disassembly of the spray gun and cleaning in a vat
that is kept closed when not in use, or,
(iv) Atomized spray into a waste container that is fitted
with a device designed to capture atomized solvent emissions.
(5) Housekeeping. All fresh and used cleaning solvents,
except semiaqueous cleaning solvents, used in solvent cleaning
operations shall be stored in nonabsorbent, nonleaking containers
that shall be kept closed at all times except when falling or
emptying. It is recommended that cloth and paper, or other
absorbent applicators, moistened with cleaning solvents be stored
in closed, nonabsorbent, nonleaking containers. Cotton-tipped
swabs used for very small cleaning operations are exempt. In
addition, the owner or operator must implement handling and
transfer procedures to minimize spills during filling and
transferring the cleaning solvent to or from enclosed systems,
vats, waste containers, and other cleaning operation equipment
that hold or store fresh or used cleaning solvents. The above
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requirements are known collectively as housekeeping measures.
Aqueous cleaning solvents are exempt from these requirements.
(d) Control equipment and monitoring.
(1) Each owner or operator may comply with the provisions
of paragraphs (B.3) (a) and (B.3) (c) (1) , (B.3) (c) (2) by using
approved air pollution control equipment provided that the
. control system has combined VOC emissions capture and control
equipment efficiency of at least 81 percent by weight.
(2) Each owner or operator shall submit a monitoring plan
that specifies the applicable operating parameter value, or range
of values, to ensure ongoing compliance with (B.3)(d)(1) . The
monitoring device shall be installed, calibrated, operated, and
maintained in accordance with the manufacturer's specifications.
(3) Each owner or operator using an enclosed spray gun
cleaner shall visually inspect the seals and all other potential
sources of leaks at.least once per month. Each inspection shall
occur while the spray gun cleaner is in operation.
B.4 RECORDKEEPING REQUIREMENTS
(a) Each owner or operator using coatings listed in
(B.3)(a) shall:
(1) Maintain a current list of coatings in use with
category and VOC content as applied.
(2) Record coating usage on an annual basis
(b) Each owner or operator using cleaning solvents required
in (B.3)(b) shall:
(1) For aqueous and semiaqueous hand-wipe cleaning
solvents, maintain a list of materials used with corresponding
water contents.
(2) For vapor pressure compliant hand-wipe cleaning
solvents:
(i) Maintain a current list of cleaning solvents in use
with their respective vapor pressures or, for blended solvents,
VOC composite vapor pressures.
(ii) Record cleaning solvent usage on an annual basis.
(3) For cleaning solvents with a vapor pressure greater
than 45 mm Hg used in exempt hand-wipe cleaning operations:
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(i) Maintain a list of exempt hand-wipe cleaning processes.
(ii) Record cleaning solvent usage on an annual basis.
(c) Each owner or operator using control equipment under
paragraph (B.3) (d) shall record monitoring parameters as
specified in the monitoring plan required under (B.3)(d)(2).
(d) Except for Specialty Coatings, any source that complies
with the recordkeeping requirements of the Aerospace NESHAP,
40 CFR 63.752, is deemed to be in compliance with the
requirements of this paragraph (B.4).
B.5 TEST METHODS
(a) For coatings which are not waterborne (water-
reducible) , determine the VOC content of each formulation (less
water) as applied using manufacturer's supplied data or Method 24
of 40 CFR part 60, Appendix A. If there is a discrepancy between
the manufacturer's formulation data and the results of the
Method 24 analysis, compliance shall be based on the results from
the Method 24 analysis. For waterborne (water-reducible)
coatings, only manufacturer's supplied data can be used to
determine the VOC content of each formulation.
(b) Cleaning solvents.
(1) For aqueous and semiaqueous cleaning solvents
manufacturers' supplied-data shall be used to determine the water
content.
(2) For hand-wipe cleaning solvents required in
paragraph (B.3) (c) (1), manufacturers' supplied data or standard
engineering reference texts or other equivalent methods shall be
used to determine the vapor pressure or VOC composite vapor
pressure for blended cleaning solvents.
(c) Control equipment. Measurements of VOC emissions
subject to paragraph (B.3)(d) shall be conducted in accordance
with EPA Methods 18, 25, and/or 25A (40 CFR 60, Appendix A).
(d) Except for Specialty Coatings, any source which
complies with the test method requirements of the Aerospace
NESHAP, 40 CFR 63.750, is deemed to be in compliance with the
requirements of this paragraph (B.5).
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TECHNICAL REPORT DATA
(Please read Instructions on reverse before completing)
1. REPORT NO.
EPA-453/D-96-016
3. RECIPIENT'S ACCESSION NO.
4. TITLE AND SUBTITLE
Control of Volatile Organic Compound Emissions from Coating
Operations at Aerospace Manufacturing and Rework Operations
5. REPORT DATE
October 1996
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
David G. Hearne, David W. Reeves
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Emission Standards Division (Mail Drop 13)
Office of Air Quality Planning and Standards
U. S. Environmental Protection Agency
Research Triangle Park, NC 27711
10. PROGRAM ELEMENT NO.
Work Assignment 134
11. CONTRACT/GRANT NO.
EPA Contract No. 68-D10115
12. SPONSORING AGENCY NAME AND ADDRESS
Midwest Research Institute
401 Harrison Oaks Boulevard
Suite 350
Gary, North Carolina 27513
13. TYPE OF REPORT AND PERIOD COVERED
Draft
14. SPONSORING AGENCY CODE
15. SUPPLEMENTARY NOTES
EPA Work Assignment Manager: Jim Szykman, ESD/PPSG
16. ABSTRACT
The draft control techniques guideline (CTG) document identifies presumptive reasonably available control
technology (RACT) for controlling volatile organic compounds (VOC) emissions from aerospace coatings and
cleaning solvents. This CTG guidance also reflects EPA's determination of best available control (BAG) measures
for this industry. Much of the CTG parallels (and is based upon) national emission standards for hazardous air
pollutants (NESHAP) for aerospace manufacturing and rework operations which were promulgated on
September 1, 1995 (60 FR 45948).
This CTG document is intended to provide State and local air pollution control authorities with an information
base for proceeding with their evaluation and analyses of RACT for their own regulations.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b. IDENTIFIERS/OPEN ENDED TERMS
c. COSATI Field/Group
Control Techniques Guidelines
Aerospace Manufacturing and Rework
Operations
Surface Coating
Cleaning Solvents
VOC
Emissions Reduction
CTG
RACT
BAG
VOC
Primers and Topcoats,
Specialty Coatings
Coating Operations
Cleaning Operations
18. DISTRIBUTION STATEMENT
Release Unlimited
19. SECURITY CLASS (Report)
21. NO. OF PAGES
20. SECURITY CLASS (faftj
22. PRICE
EPA Form ZTW-1 (Rev. 4-77)
PREVIOUS EDITION IS OBSOLETE
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EPA Region 5 Library
U S Environmental Protection Agency
Region 5, Library (PL-12J)
77 West Jackson Boulevard, Utn
Chicago, It 60604-3590
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