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EPA Self-Audit and Inspection Guide
Organic Finishing of Metals

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Chemical Coatings Removal: Regulatory Requirements

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). Chemical coatings removal operations often use organic solvent based chemicals. Evaporation of the solvents from tanks and spray systems may produce sufficient VOC and HAP emissions to subject an operator to major source requirements and Title V permitting requirements. Under the standards for the aerospace industry (40 CFR Part 63 Subpart GG), there are specific requirements for chemical depainting operations.

Painting and solvent cleaning processes are regulated by federal rules that are implemented by state agencies. These regulations limit emissions from operations, such as those coating metal furniture, miscellaneous metal parts, plastic parts, autos, trucks, boats and large appliances. Coating facilities affected by these regulations need to obtain permits, control and monitor air emissions, and submit reports. Use This PCRC Tool to determine which regulations and standards apply to your operations.

Controlling VOC emissions can be completed in several ways. Evaporation can be minimized by covering tanks, keeping a lower volume level of solvent solution in tanks, or providing a barrier layer of water or cold air above the organic solvent solution. Otherwise, air pollution control equipment is required on exhaust systems to recover the VOCs and HAPs before they are released from the facility.

As part of the Clean Water Act, Effluent Guidelines and Standards for Metal Finishing (40 CFR Part 433) have been established that limit concentrations of heavy metals, toxic organics, and conventional pollutants in wastewater streams. Several components of chemical coatings removal operations are classified as water pollutants including organic solvent solutions, caustic solutions, or salt solutions. Also, the residual coating solids or sludge in the solutions may contain metals. These materials can enter the wastewater through liquid dripping off of parts, when cleaning equipment, and from accidental spills or leaks in 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). Used chemical coatings removal solutions may contain constituents listed or characterized as hazardous wastes. The residual coatings materials remaining in the solutions will also contribute to the volume and determination of hazardous wastes. 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.

The Emergency Planning and Community Right-to-Know Act (EPCRA) requires facilities to notify employees, customers and the surrounding community of certain hazardous chemicals and materials (40 CFR Parts 355 and 370) that are present on-site. Large chemical coatings removal operations may use hazardous materials in sufficient quantities to subject a facility to several EPCRA requirements. Facilities may be required to inform the local emergency planning committee (LEPC) and the state emergency response commission (SERC) of the materials stored and used on-site, devise emergency response plans for reacting to spills, and notify authorities of accidental spills and releases (40 CFR Parts 302 and 355). The materials used in chemical coatings removal solutions may also require facilities to submit Material Safety Data Sheets (MSDS) for these materials to state, regional, and local organizations, while disposed volumes of the material may have to be documented on annual Toxic Release Inventory reports (40 CFR Part 372).


  • Do chemical coatings removal solutions come in contact with water streams? If so, do concentrations of pollutants exceed limits established by the facility NPDES permit or POTW discharge agreement?
  • Are all chemical coatings removal solutions and wastes labeled and packaged in accordance with 40 CFR Part 262, Subpart C? Are manifest forms completed for wastes to be shipped for disposal?
  • Has the facility participated in local, regional, or state emergency response planning activities? Have facility response plans been developed and coordinated with local authorities?

Chemical Coatings Removal: Common Causes of Violations

  • Emission of volatile organic compounds from chemical coatings removal solutions may occur and exceed limits established in a Clean Air Act Title V permit. The harmful emissions can be captured and treated to prevent their release to the atmosphere. Common air pollution control tactics include solvent recovery, solvent incineration, and solvent concentration.
  • Chemical coatings removal solutions are liquid materials that can contaminate water streams. This may occur accidentally, as with spilt material entering a storm sewer. Contaminated water streams may contain pollutants, including solvents, residual sludges, and oils, in concentrations that exceed the limits established by facility NPDES or POTW permits. Effluent, then, may not be directly released to water systems or to publicly owned treatment works without pretreatment.
  • Used chemical stripping solutions containing oils, grease, coating sludges, and other contaminants may be classified as hazardous waste according to RCRA. These materials must be labeled, stored, and disposed of properly.
  • Chemical coatings removal solutions may contain chemicals defined as hazardous or extremely hazardous substances. Depending on the quantity of material on-site, facilities must have an MSDS for each solution, maintain records for TRI reporting, and cooperate with local emergency planning committees.

Chemical Coatings Removal: Sources of Pollution

  • Chemical coatings removal solutions contain materials classified as volatile organic compounds, hazardous air pollutants, and/or ozone-depleting chemicals.
  • Chemical coatings removal solutions may spill due to improper handling or leaks in tanks, pipes, hoses, etc. The liquid material may enter storm sewers if not properly contained.
  • In addition to the solvents, used chemical coatings removal solutions may contain coating solids, grease, oils, and heavy metals that would classify the material as a hazardous substance.
  • Coating residue and metal particulates may be separated from chemical coatings removal solutions as a sludge. Depending on the constituents of the coating material, the sludge may be classified as a hazardous waste.
  • Heat (required for some chemical coatings removal solutions) consumes energy.

Chemical Coatings Removal: Pollution Prevention Alternatives

  • Chemical coatings removal may be considered a pollution prevention alternative since it aids in the proper application of coating materials thereby reducing rework or reject parts. However, other concerns make it less acceptable than other coatings removal methods.
  • Use mechanical coatings removal methods (or a combination of mechanical methods and less hazardous chemical coatings removal methods) to eliminate or reduce the use of hazardous materials.
  • Substitute waterborne chemicals, semi-aqueous chemicals or organic solvents with lower vapor pressures for chemical coatings removal solutions. Compared to traditional chemical coatings removal solutions, waterborne chemicals and low vapor pressure solvents release fewer volatile organic compounds.
  • Restrict traffic in chemical storage areas to reduce spills and accidents. Keep storage and work areas clean so that spills and leaks are more noticeable and reaction time is reduced.
  • Optimize process to strip properly with minimal solution and with lower concentrations. Proper adjustment of operating parameters, such as time, agitation, solution concentration, and temperature, will improve coatings removal without requiring stronger solvents. Modify part arrangement to ensure that cleaner reaches all surfaces.
  • Conserve energy by operating at optimum temperature, and by covering baths, using insulated tanks, or using waste heat from other processes to heat solution.
  • Enclose or cover containers of chemical coating removal solutions when not in use to minimize the release of solvent vapors and lower contamination from facility dust and dirt. Turning off spray systems and maintaining a cool barrier zone above chemical tanks can also reduce the evaporation rate.
  • Minimize water consumption by utilizing counter-current rinse baths. Backflow water from final rinse, to pre-rinse, to stripping baths before disposing.
  • Remove contaminants from chemical coatings removal solutions to retain cleaning effectiveness. Separate coating residue, dirt, oils, and other contaminants using filtration, gravity separation, or membrane technologies (crossflow filtration). Reducing heat and stopping agitation will promote separation of contaminants in batch systems.
  • Segregate non-hazardous wastewater and other materials from hazardous organic solvents, and label containers to prevent mixing. Separation of the materials reduces the amount of hazardous waste that is produced.
  • Recycle spent solvents with recovery units. Use semi-dirty solvent materials for other cleaning jobs - paint spills, application equipment, accessory clean-up, where some contaminants will not matter.
  • Check chemical coatings removal equipment regularly for leaks and repair them. Items to check include tanks, pumps, pipes, hoses, valves, fittings, and storage containers.
  • Minimize need for coatings removal by improving other process steps. Reduce coating failure by handling parts carefully, and by performing good cleaning, coating application and curing. Determine if time between rework can be lengthened to reduce need for chemical coatings removal.
  • 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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