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Table of Contents
Roll and Coil Coating: Regulatory Requirements
Air
The Clean Air Act regulates the emission of
volatile organic
compounds (VOCs) (40 CFR Part 60) and hazardous
air pollutants (HAPs) (40 CFR Part 61 and
40 CFR Part 63). Depending on the solvent
content of the coating material used with roll and coil methods, solvents
can evaporate and produce sufficient VOC and HAP emissions to subject an
operator to major source requirements
and Title V permitting requirements. The Act also provides specific standards of performance to control emissions
from coil coating operations (40 CFR Part 60 TT).
Controlling VOC emissions from roll and coil coating areas can be accomplished
in several ways. First, a coating material with a lower VOC content
can be used. Second, air
pollution control equipment can be attached to the ventilation system
to capture VOCs prior to their release into the atmosphere.
Water
As part of the Clean Water Act, Effluent
Guidelines and Standards for Coil Coating (40 CFR Part 465) have been
established that limit concentrations of heavy
metals, toxic organics, and
conventional pollutants
in wastewater streams. The organic solvents often contained in liquid
coatings used with roll and coil coating application methods may be classified
as toxic organics. These materials can enter the wastewater when
cleaning coatings from containers or equipment. Actual limits for
effluent constituents are dependent on the size of the operation and the
amount of wastewater generated from the facility. If the facility discharges
directly to receiving waters,
these limits will be established through the facility's National
Pollutant Discharge Elimination System (NPDES) permit (40
CFR Part 122). Facilities which are indirect dischargers releasing
to a POTW
must meet limits in the POTW's discharge agreement. Wastewater streams
with concentrations exceeding permit limits will require pretreatment
prior to discharge to receiving waters or to a publicly
owned treatment works. Pretreatment may include separation of
liquid wastes to remove solvents, and settling or precipitation of solid
materials.
Solid and Hazardous Waste
Under the Resource Conservation and Recovery
Act (RCRA), organic finishing facilities are required to manage listed
and characteristic hazardous wastes (40 CFR Part
261). Liquid coatings used with roll and coil coating application
methods may contain constituents listed or characterized as hazardous wastes. Materials contaminated with the coatings, such as roller surface covers,
conveyor components, and rags or other materials used for cleaning, may
require treatment as hazardous waste depending on their formulation. Hazardous waste management
(40 CFR Part 262) includes obtaining permits
for the facility in order to generate wastes, meeting accumulation limits
for waste storage areas, and manifesting waste containers for off-site
disposal. Responsibilities will vary according to the amount of hazardous
waste generated; facilities generating at least 100 kilograms of hazardous
waste per month must comply with the hazardous waste generator requirements
of 40 CFR Part 262.
Each state and/or region is primarily responsible for the regulation
of non-hazardous solid wastes (those not governed by the hazardous waste
provisions of RCRA). Check with state environmental agencies for
specific information or guidance.
Self-Audit/Inspection
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Do exhaust air streams have air pollution control equipment attached? Is that air pollution control equipment working properly? Does final
exhaust air have concentrations of pollutants below required levels?
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Does the spray system produce a liquid waste stream? Do concentrations
of pollutants in the waste stream exceed limits established by the facility
NPDES or POTW permit?
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Are wastes contaminated with coating material classified as hazardous? If so, are the wastes handled and manifested in accordance with 40
CFR part 262, Subpart B? Are hazardous wastes segregated from
non-hazardous wastes?
Roll and Coil Coating: Common Causes of Violation
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Roll and coil coating systems apply coating materials which may include
solvents classified as volatile organic compounds and/or hazardous air
pollutants. The solvents evaporate and may accumulate above limits
allowed by Clean Air Act Title V permits. Ventilation and exhaust
systems must operate properly to ensure the vapors are removed from the
coating area. Air pollution control equipment should be attached
to exhaust systems to recover or destroy volatile organic compounds instead
of releasing them to the air.
- Roll and coil coating systems utilize liquid coating materials and
solvent and water rinses which can contaminate water streams. Contamination
may occur when cleaning equipment or from accidental spills or leaks from
equipment. Contaminated water streams may contain pollutants or heavy
metals in concentrations that exceed the limits established by facility
NPDES or POTW discharge agreement permits. In such cases, effluent,
may not be directly released to water systems or to publicly owned treatment
works without pretreatment.
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Roll and coil coating systems utilize liquid coating materials with organic
solvents which must be stored, manifested, and disposed of according to
40 CFR Part 262 if classified as hazardous waste
under 40 CFR Part 261.
Roll and Coil Coating: Sources of Pollution
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Roll and coil coating systems apply liquid coating materials that contain
components classified as volatile organic compounds, hazardous air pollutants,
and/or ozone depleting substances.
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Roll and coil coating systems generate some coating material waste. Some
excess coating material is necessary to coat all rollers continuously. These coating materials become waste when cleaning.
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Roll and coil coating systems require regular cleaning which creates solvent
and/or water wastes.
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Roll and coil coating systems may leave bare spots on work pieces if the
coating material does not cover a location on the roller. Bare spots
may necessitate rework or disposal of work piece.
Roll and Coil Coating: Pollution Prevention Alternatives
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Use liquid coating materials with low organic solvent content to minimize
the amount of volatile organic compounds that will be volatized and to
reduce the volume of solid and liquid hazardous waste created.
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Roll and coil coating systems provide pollution prevention over traditional
spray application systems due to the higher transfer efficiency (above
95%), and lower volatilization of organic solvents.
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Schedule paint jobs to minimize changing colors in roll and coil coating
equipment. Paint with light colors first, then darker ones; lighter
coating does not need to be completely removed from the equipment, but
can blend into the darker coating. Since most roll and coil lines
apply only one color, this is typically not an issue.
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Clean roll and coil coating equipment regularly to prevent coating materials
from drying on rollers and feed lines. Use water in cleaning steps
to reduce the amount of organic solvents used and the amount of hazardous
waste generated. Perform initial cleaning with used solvents, saving
fresh solvents for final cleaning stages.
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Segregate non-hazardous coating solids and water from hazardous solvents
and thinners, and label containers to prevent mixing. Separation
of the materials reduces the amount of hazardous waste that is produced. Coating material solids can be dried and treated as a solid waste allowing
for disposal in a landfill.
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Maintain roll and coil coating equipment to sustain proper operation. Make sure valves, gauges and rollers are in proper working order.
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Keep roll and coil coating areas clean so that problems with equipment
can be found and fixed quickly, and accidents can be prevented.
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Train employees on safe handling of materials and wastes and encourage
continuous improvement. Training familiarizes workers with their
responsibilities, which reduces spills and accidents.
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