Metal Painting and Coating Operations

Table of Contents  Background  Regulatory Overview  Planning P2 Programs  Overview of P2  Surface Preparation
Alternatives to Solvent-Borne Coatings  Application Techniques  Curing Methods  Equipment Cleaning

Regulatory Overview

The use of solvents in coating formulations and in other areas of the coating process poses a number of risks to human health and the environment. To reduce the risks resulting from exposure to these substances, the federal government and individual states have regulated the generation and management of wastes from paint and coating operations. Applicable regulations depend on the environmental medium to which the waste is released (e.g., air, land, or water) and the regulatory status of the generator (IHWRIC, p. 10).

A discussion of individual state laws is beyond the scope of this document. However, this chapter provides an overview of the major federal statutes that affect coating processes, including the Clean Air Act (CAA) and the Clean Air Act Amendments of 1990 (CAAA), which regulate air releases; the Resource and Conservation Recovery Act (RCRA), which regulates hazardous wastes; and the Clean Water Act (CWA), which regulates wastewaters. For an overview of the regulatory status under the CAAA and RCRA for particular solvents used in paint and coating operations, see table 1. Technical assistance providers should check with their state regulatory programs to see if their state has imposed requirements stricter than those developed under the federal programs. Coating operations might also be affected by a number of other federal and state regulations. Many of these regulations are industry specific rather than process specific.

Table 1. Common Solvents, Federal Regulatory Status (IHWRIC, p. 5)

Solvent RCRA Hazardous Air Toxics Program a
Aliphatic Hydrocarbons
Mineral Spirits
Yes Maybe b
Aromatic Hydrocarbons
Toluene
Xylene
Yes
Yes
Yes
Yes
Esters
Ethyl Acetate
Butyl Acetate
Yes
Yes
No
No
Ketones
Acetone
Methyl Isobutyl Ketone
Methyl Ethyl Ketone
Yes
Yes
Yes
Noc
Yes
Yes
Glycol Ethers
Monoethyl Ether
No No
Alcohols
Ethyl Alcohol
Butyl Alcohol
Yes
Yes
No
No

a Under the 1990 Clean Air Act Amendments.
b Depends on the composition of the mineral spirits; some cheaper blends may contain aromatic solvents such as benzene.
c Acetone has recently been delisted from the CAAA's Title III list of VOCs. However, technical assistance providers should not promote the use of acetone to achieve environmental compliance. Material substitution using acetone does not constitute a pollution prevention option.

Clean Air Act

The Clean Air Act and the Clean Air Act Amendments of 1990 consist of 11 chapters or titles that require EPA to establish national standards for ambient air quality and to work with states to implement, maintain, and enforce these standards. Of these titles, none have attracted more attention from industry than the Title III air toxics program, which brought many previously unregulated companies and processes under legislative control (Freeman, p. 34).

Under Title III, EPA created a list of 189 hazardous air pollutants (HAPs) of which 149 also are VOCs. Surface coating operations of all kinds are major users of these compounds. Commonly used compounds include toluene, xylene, MEK and MIBK. VOCs not regulated under the air toxics program might be regulated under Title I provisions for ozone non-attainment areas (Falcone, p. 35). Details of these titles are provided below.

Air Releases from Coatings Processes

  • VOCs, which contribute to ozone pollution
  • Heavy metal dust from pigments
  • Atomized paint from spray applications (IHWRIC, p. 10)

Air Toxics

Under Title III, facilities that emit HAPs are grouped into categories with similar operating processes, including the process of surface coating. Individual sources within a category are considered "major" if they emit or have the "potential to emit" 10 or more tons per year of any HAP on the list or 25 or more tons per year of a combination of HAPs. EPA defines "potential to emit" as the amount of emissions that a facility could release if it operated at maximum capacity 24 hours per day, 365 days per year.

Under Title III, major sources are subject to maximum achievable control technology (MACT) standards. MACT standards specify the maximum degree of reduction in the emission of HAPs that must be met through the use of traditional control technologies as well as through pollution prevention techniques. EPA has listed 16 surface coating processes as source categories subject to MACT standards, although not all of these surface coating processes apply to the coating of metal substrates. MACT standards are to be promulgated according to the schedule in table 2. Existing sources generally will have up to 3 years from the effective date of the standards to comply.

Table 2. Scheduled Date for MACT Standards for Surface Coating (EPAm, p. 1-5)

Source Categories Scheduled Date for Emissions Standards
Aerospace Industries
Auto and Light Duty Truck (Surface Coating)
Flat Wood Paneling (Surface Coating)
Large Appliances (Surface Coating)
Magnetic Tapes (Surface Coating)

Manufacture of Paints, Coatings, and Adhesives
10/8/96
11/15/00
11/15/00
11/15/00
11/15/94 (final rule issued 12/15/96; compliance 2 or 3 years)
11/15/00
Metal Can (Surface Coating)
Metal Coil (Surface Coating)
Metal Furniture (Surface Coating)
Miscellaneous Metal Parts and Products (Surface Coating)
Paper and Other Webs (Surface Coating)
11/15/00
11/15/00
11/15/00
11/15/00
11/15/00
Plastic Parts and Products (Surface Coating)
Printing, Coating, and Dyeing of Fabrics
Printing/Publishing (Surface Coating)
Shipbuilding and Ship Repair (Surface Coating)
Wood Furniture (Surface Coating)
11/15/00
11/15/00
11/15/94 (final rule 5/30/96; compliance 3 years)
11/15/94 (final rule issued 12/15/95; compliance 1 year)
9/7/95 (final rule issued 2/9/96; compliance 11/21/97)

NOTE: Work is beginning on the development of the 2000 regulations. Meetings were held in April of 1997 and workgroups are organizing to further develop the regulations.

Ozone

Under Title I, EPA established national ambient air quality standards (NAAQS) to limit levels of "criteria pollutants," including carbon monoxide, lead, nitrogen dioxide, particulate matter, ozone, and sulfur dioxide. The federal government has developed control technique guidelines (CTGs) which deal with a number of sources of air pollution in nonattainment areas (i.e., geographic areas that did not meet the NAAQS). These guidelines require the use of reasonably available control technologies (RACT).

For surface coating sources, the federal CTGs generally define RACT in terms of the VOC content limits of a coating; that is RACT is the mass of VOC per unit volume of coating (minus water) as applied (ready for application). In some cases, however, RACT is defined in terms of the percentage emission reduction achieved with add-on control devices, equipment specifications, record keeping, reporting requirements, and exemption levels (EPAf, p. 2-1). While limits are based on specific industry groups and applications, the VOC limit of 340 g/l (2.8lb/gal) can be considered an unofficial national standard (Freeman, p. 486). For more specific information on EPA guidelines for VOCs in coatings, see table 3.

Table 3. EPA Guidelines for Maximum VOC Content of Coatings (SWR, p. 46)

Process

Limitation (pounds per gallon)

Can Coating
  • Sheet basecoat and overvarnish; two-piece can exterior
  • Two-, three-piece can interior body spray; two-piece can exterior end
  • Side-seam seal
  • End sealing compound


2.0; 2.8
3.6; 4.2
5.5
3.7
Coil Coating 2.6
Fabric Coating 2.9
Vinyl 3.8
Paper 2.9
Auto and Light-Duty Truck
  • uPrime
  • uTopcoat
  • uRepair


1.9
2.8
3.0
Metal Furniture 3.0
Magnet Wire 1.7
Large Appliance 2.8
Miscellaneous Metal Parts 0.4-4.4
Wood Paneling
  • Printed interior
  • Natural finish hardwood
  • Class II hardwood


1.7
3.2
2.7

Other Requirements

Under Title V, the permitting provision of the CAAA, all major sources must apply for operating permits. Accurate information on source pollutants and emission quantities must be gathered before application submittal (Falcone, p. 35). Information about calculating VOC and HAP emissions from coatings processes can be found in appendix B. State and local governments oversee, manage, and enforce much of the permitting program and many of the other requirements of the CAAA. For more information pertaining to the CAA, see 40 CFR Parts 50-99.

Resource Conservation and Recovery Act

Under the Resource Conservation and Recovery Act Subtitle C, EPA has established a "cradle-to-grave" system governing hazardous waste. Most RCRA requirements are not industry specific but apply to any company that transports, treats, stores, or disposes of hazardous waste. Wastes generated during the application of paints and coatings might be considered hazardous because of the presence of solvents or toxic metals (IHWRIC, p. 10).

RCRA Wastes from Coating Processes

  • Organic solvents commonly used in paint formulations
  • Waste paint containing heavy metals
  • Materials used for surface preparation and equipment cleaning (IHWRIC, p. 12)

Waste Characterization

A waste is considered hazardous if it is included on one of the four EPA lists of hazardous wastes; if it displays one or more of the characteristics of hazardous waste (ignitability, corrosivity, reactivity or toxicity); or if it is a mixture that contains a listed hazardous waste.

  • Listed wastes include acutely hazardous commercial chemical products and toxic commercial chemical products, designated with the code "P" or "U," respectively; hazardous wastes from specific industries/sources, designated with the code "K"; or hazardous wastes from nonspecific sources, designated with the code "F".

    F wastes are of particular interest to paint and coating operations because they are generic wastes commonly produced during coating application. Examples from this list include spent solvents used in cleaning and used paint thinners such as xylene and toluene (IWRCb, p. 15).
  • Characteristic wastes include those that are ignitable, corrosive, reactive or toxic. Ignitable wastes have a flashpoint of less than 140F and are easily combustible or flammable. Corrosive wastes have a pH of 2 or less, or of 12.5 or greater and can dissolve metals or other materials. Reactive wastes are unstable, or undergo rapid or violent chemical reaction with water or other materials. Toxic wastes contain concentrations of heavy metals, certain solvents, or pesticides in excess of corresponding regulatory parameters determined by the Toxicity Characteristic Leaching Procedure (TCLP). Characteristic wastes are designated with the EPA hazardous waste code "D." See table 4 for more information on hazardous wastes generated from coatings operations.

Table 4. Hazardous Wastes Generated from Coatings Operations (EPAb, p. 96-97)

EPA Hazardous Waste Number Hazardous Waste
D006 (cadmium)
D007 (chromium
D008 (lead)
D009 (mercury)
Wastes that are hazardous due to the characteristic of toxicity for each of the D007 (chromium) constituents.
F001 Halogenated solvents used in degreasing: tetrachloroethylene, methylene chloride, 1,1,1-trichloroethane, carbon tetrachloride, and chlorinated fluorocarbons; all spent solvent mixtures/blends used in degreasing con- taining, before use, a total of 10 percent or more (by volume) of one or more of the above halogenated solvents or those solvents listed in F002, F004, and F005; and still bottoms from the recovery of these spent solvents and spent solvent mixtures.
F002 Spent halogenated solvents: tetrachloroethylene, methylene chloride, trichlo- roethylene, 1,1,1-trichloroethane chlorobenzene, 1,1,2-trichloro-1,2,2- trifluoroethane, ortho-dichlorobenzene, trichlorofluoromethane, and 1,1,2- trichloroethane; all spent solvent mixtures/blends containing, before use, one or more of the above halogenated solvents or those listed in F001, F004 , F005; and still bottoms from the recovery of these spent solvents and spent solvent mixtures.
F003 Spent nonhalogenated solvents: xylene, acetone, ethyl acetate, ethyl ben- zene, ethyl ether, methyl isobutyl ketone, n-butyl alcohol, cyclohexanone, and methanol; all spent solvent mixtures/blends containing, before use, only the above spent nonhalogenated solvents; and all spent solvent mixtures/blends containing, before use, one or more of the above nonhalogenated solvents, and a total of 10 percent or more (by volume) of one of those solvents listed in F001, F002, F004, and F005; and still bottoms from the recovery of these spent solvents and spent solvent mixtures.
F004 Spent nonhalogenated solvents: cresols and cresylic acid, and nitrobenzene; all spent solvent mixtures/blends containing, before use, a total of 10 percent or more (by volume) of one or more of the above nonhalogenated solvents or those solvents listed in F001, F002, and F005; and still bottoms from the recovery of these spent solvents and spent solvent mixtures.
F005 Spent nonhalogenated solvents: toluene, methyl ethyl ketone, carbon disul- fide, isobutanol, pyridine, benzene, 2-ethoxyethanol, and 2-nitropropane; all spent solvent mixtures/blends containing, before use, a total of 10 percent or more (by volume) of one or more of the above non-halogenated solvents or those solvents listed in F001, F002, or F004; and still bottoms from the recovery of these spent solvents and spent solvent mixtures.

Generator Status

To determine what a facility must do to comply with RCRA requirements, the facility must first determine its generator status. Generator status is based on the amount of waste generated on a monthly basis. The following criteria determine the quantity of waste that is regulated by RCRA:

1) material remaining in a production process is not counted as waste until it is no longer being used in that process.

2) waste discharged directly and legally to a POTW in compliance with CWA pretreatment standards is not counted toward RCRA generation total.

3) any material that is characteristic or listed as a hazardous waste, and is accumulating after its removal from the process before being sent off site for treatment, storage, or disposal, is counted toward RCRA Subtitle C generation total.

Facilities that generate hazardous waste are subject to certain waste accumulation, manifesting, and record keeping standards based on the amount of waste generated. RCRA specifies three categories of waste generators. The following outlines the basic guidelines for generator status; be aware, however, that state guidelines may vary.

  • Conditionally exempt small quantity generators (CESQGs) generate less than 220 pounds of hazardous waste, or 2.2 pounds of acute hazardous waste (K wastes), per calendar month. CESQGs cannot accumulate more than 2,200 pounds of nonacute hazardous waste (or 1 kilogram of acute hazardous waste).
  • Small quantity generators (SQGs) generate 220 to 2,200 pounds of hazardous waste per calendar month. SQGs cannot accumulate more than 13,200 pounds. Storage time is restricted to 180 days.
  • Large quantity generators (LQGs) generate more than 2,200 pounds of hazardous waste per calendar month. Storage time is restricted to 90 days.

Each state has varying degrees of regulation for the three generator classes. At a minimum, however, EPA requires each class to comply with the following requirements:

Large Quantity Generators

  • Notify the US EPA or state and obtain an EPA ID number from the state regulatory agency
  • Store waste for no more than 90 days
  • Comply with container standards and tank rules
  • Prepare and retain a written contingency plan
  • Prepare and retain a written training plan which includes information on the annual training of employees
  • Prepare a written waste minimization plan
  • Dispose of hazardous materials only at a RCRA permitted site
  • Only use transporters with EPA ID numbers
  • Use proper Department of Transportation (DOT) packaging and labeling
  • Use the full Uniform Hazardous Waste Manifest
  • Place a 24-hour emergency number on all manifests
  • Report serious spills or fires to the National Response Center
  • Obtain a DOT registration number for shipments over 5,000 pounds
  • Keep all records for 3 years
  • Make sure that any treatment or recycling done onsite is permitted
  • Report missing shipments in writing
  • Submit biennial reports of hazardous waste activities, including waste minimization

Small Quantity Generators

  • Notify the US EPA or state and obtain an EPA ID number from the state regulatory agency
  • Store waste for no more than 180 days (270 days if the waste is shipped more than 200 miles)
  • Comply with container standards and tank rules
  • Dispose of hazardous materials only at a RCRA permitted site
  • Only use transporters with EPA ID numbers
  • Use proper Department of Transportation (DOT) packaging and labeling
  • Use the full Uniform Hazardous Waste Manifest
  • Place a 24-hour emergency number on all manifests
  • Post emergency response telephone numbers near telephones
  • Provide informal employee training
  • Make sure that any treatment or recycling done onsite is permitted
  • Report missing shipments in writing
  • Keep all records for 3 years

Conditionally Exempt Small Quantity Generators

  • Avoid accumulating more than 1,000 kilograms (2,200 pounds) of hazardous waste onsite at any one time
  • Send waste to a facility that is at least approved to manage municipal or industrial solid waste

Toxics Release Inventory Reporting

Some coating facilities may have to publicly report many of the chemicals they use under the federal Toxic Release Inventory (TRI) reporting requirement. Facilities report information on a TRI data form (Form R) for each toxic chemical that is used over the threshold amount. Basic information that is reported in a Form R includes the following:

  • Facility identification
  • Parent company information
  • Certification by corporate official
  • SIC code
  • Chemical activity and use information
  • Chemical release and transfers
  • Off-site transfer information
  • On-site waste treatment
  • Source reduction and recycling activities

The releases and transfers reported on a Form R include the following:

  • Emissions of gases or particulates to the air
  • Wastewater discharges into rivers, streams, and other bodies of water
  • Releases to land onsite including landfill, surface impoundment, land treatment, or other mode of land disposal
  • Disposal of wastes in underground injection wells
  • Transfers of wastewater to POTWs
  • Transfers of wastes to other off-site facilities for treatment, storage, and disposal

A facility must fill out Form R if it meets the following criteria:

  • The facility is included in SIC codes 20 to 39
  • The facility has 10 or more full-time employees
  • The facility manufactures, processes, or "otherwise uses" any listed material in quantities equal to or greater than the established threshold for the calendar year

The manufacturing and processing thresholds have dropped over the reporting years from 75,000 pounds in 1987 to 25,000 pounds in 1989. For a chemical "otherwise used," the threshold amount is 10,000 pounds. Technical assistance providers can use TRI data to develop an aggregate picture of the releases and transfers from a facility.

Clean Water Act

The primary objective of the Federal Water Pollution Control Act, commonly referred to as the Clean Water Act (CWA), is to restore and maintain the chemical, physical and biological integrity of the nation's surface waters. Pollutants regulated under the CWA are classified as "priority" pollutants. These include various toxic pollutants; "conventional" pollutants, such as biochemical oxygen demand (BOD), total suspended solids (TSS), fecal chloroform, oil and grease, and pH; and "non-conventional" pollutants, including any pollutant not identified as either conventional or priority.

National Pollutant Discharge Elimination System (NPDES)

Under the CWA, most point sources of wastewater (e.g., discharge pipes or sewers) discharging to waterways require a National Pollutant Discharge Elimination System permit. Permits, issued by either EPA or an authorized state (EPA has presently authorized 40 states to administer the NPDES program), specify levels of toxicity and other characteristics that must be achieved prior to discharge. Pretreatment of the wastewater is generally necessary. Wastewater generated from coating application might be regulated because of the presence of organic solvents or heavy metals (IHWRIC, p. 11).

Wastewaters from Coatings Processes

  • Wastewaters from equipment cleaning and surface preparation
  • Rinsing of a surface after paint removal (IHWRIC, p. 11)

Pretreatment Program

Another type of discharge that is regulated by the CWA is one that goes to a publicly-owned treatment works (POTWs). The national pretreatment program controls the indirect discharge of pollutants to POTWs by industrial users. Facilities regulated under this program must meet certain pretreatment standards. The goal of the pretreatment program is (1) to protect municipal wastewater treatment plants from damage that can occur when hazardous, toxic, or other wastes are discharged into a sewer system and (2) to protect the quality of sludge generated by these plants. For more information about the CWA, see 40 CFR Part 433.