EPA Self-Audit and Inspection Guide
Organic Finishing of Metals

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

• 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?

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? Are all wastes contaminated with coating materials properly labeled and packaged in accordance with 40 CFR Part 262, Subpart C? 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

• 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.

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 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. 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. Roll and coil coating systems require regular cleaning which creates solvent and/or water wastes. 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

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. 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. 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. 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. 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. Maintain roll and coil coating equipment to sustain proper operation. Make sure valves, gauges and rollers are in proper working order. Keep roll and coil coating areas clean so that problems with equipment can be found and fixed quickly, and accidents can be prevented. Train employees on safe handling of materials and wastes and encourage continuous improvement. Training familiarizes workers with their responsibilities, which reduces spills and accidents.