EPA Self-Audit and Inspection Guide
Organic Finishing of Metals

Table of Contents

Powder Coatings: Regulatory Requirements

Air
The Clean Air Act regulates the emission of particulate matter of various sizes (40 CFR Part 50). Small dry powder particles can be suspended in exhaust air streams in amounts that would subject an operator to Title V permitting requirements. One common control technology for capturing particulate matter is a dry filter to capture the particles. These technologies are typically used in conjunction with the application method chosen for a facility. Due to the very low solvent content of powder coating materials, regulations concerning volatile organic compounds (VOCs) or hazardous air pollutants (HAPs) are typically not a concern. However, if large quantities of the material are used, then these air emissions may cause a problem. VOCs or HAPs should be monitored during curing stages when the materials would be released.

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.

Water
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, such as suspended solids, in wastewater streams. Powder coating particles may be classified as suspended solids if found in a large quantity. These materials can enter the wastewater when cleaning powder coatings from containers, equipment or spills. 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). Powder coatings may contain constituents listed or characterized as hazardous wastes. Residual powder coating materials, their containers, and contaminated materials (such as rags, masking material, coveralls, and filters, etc.) may require treatment as a 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 material 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 powder coatings come in contact with exhaust air streams? If so, do concentrations of particulate matter exceed the limits established by facility air permits?

Do powder coatings 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 powder coatings and powder coating wastes properly labeled and packaged in accordance with 40 CFR Part 262, Subpart C? Are wastes contaminated with powder coatings 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?

Powder Coating Material: Common Causes of Violation

•  Powder coatings are small, dry particles that may be suspended in air currents at levels exceeding concentrations for dust and respirable particulates established by Title V permits.

Powder coatings contain some amount of solvents classified as volatile organic compounds that can volatize. Most powder coatings have a very low VOC content; but when large volumes of the material are used, the ambient level of the volatile organic compounds may be an issue. Containers with small amounts of powder coatings may be considered hazardous solid waste that must be stored, manifested and disposed according to the RCRA standards at 40 CFR Part 262.

Powder Coating Material: Sources of Pollution

•  Powder coating materials can create a fine dust if handled in open containers exposed to air currents.

Powder coatings contain some amount of materials classified as volatile organic compounds and hazardous air pollutants. Powder coatings may spill due to improper handling or holes in containers. The dry material may become contaminated with dust, dirt, other types of powder coating materials, or other undesirable solid particles prohibiting its reuse. Powder coatings may be stored improperly and no longer meet quality standards, thus becoming waste. In addition, coatings that are not used up completely in a job and have no use in another job are considered waste. Powder coatings come in containers that become solid waste once empty or when the coating is no longer useable or needed. Containers can range from small bags with a few ounces of powder to large bags or barrels. Residual coating material left inside the container adds to the volume of solid waste. Powder coatings require heated curing cycles unlike liquid coatings that may be air dried in some cases. This may increase energy consumption for curing processes.

Powder Coating Material: Pollution Prevention Alternatives

• In comparison with traditional solvent-based coatings, powder coatings are a pollution prevention alternative in and of themselves. The volatile organic compound content is much lower than for solvent-based coatings. In addition, the higher solids content of powder coatings results in a lower volume of material needed for a given surface area.
Proper scheduling and procurement can reduce the amount of residual coating material waste. To reduce residual coatings, buy only as much material as needed to complete job. Mix remaining light colored coatings into darker colored coatings where possible. Purchase coating materials in the largest containers possible for the volume; since the surface area to volume ratio of the container is lower, less material is left on the inside of the containers to be thrown away. Work with coating vendors to have larger containers returned for refilling. Rotate stock of coatings to use older material first (first in - first out practice). Before discarding an expired coating, test to see if it would still meet quality requirements. Donate or sell old and unwanted coating materials as raw material to others or see if vendor will take it back. Restrict traffic in storage areas to reduce spills and accidents. Keep storage and work areas clean so spills are more noticeable and reaction time for cleanup is reduced. Control the temperature in storage areas to prevent the freezing and heating of coating materials that will spoil them. Enclose or cover containers of coating material when not in use. Closed containers reduce contamination from facility dust and dirt. Closed containers also minimize exposure to water and water vapors that are readily absorbed by the powder materials. Wet powder coatings form large clumps that will not perform properly in application equipment. Train employees on safe handling of materials and wastes and encourage continuous improvement. Training familiarizes workers with their responsibilities, which reduces spills and accidents.