October 1997

If you own or operate a Hard or Decorative Chromium Plating or Anodizing Tank you are required to comply with the National Emission Standards for Hazardous Air Pollutants (NESHAP), which has been written for these processes as mandated by the 1990 Clean Air Act. In general, this means you must:
• Limit tank emissions
• Perform monitoring
• Establish work practice standards
• Keep records
• Perform initial testing, and
• Submit reports.

The 1990 Clean Air Act (CAA) directs the U.S. Environmental Protection Agency (EPA) to regulate emissions into the air of 189 toxic chemicals. To control emissions of these chemicals, the EPA issues National Emission Standards for Hazardous Air Pollutants (NESHAPs) for particular industries or industrial processes.

On Jan. 25, 1995, the EPA finalized regulations known as the NESHAP for Chromium Emissions From Hard and Decorative Chromium Electroplating and Chromium Anodizing Tanks. There is strong evidence suggesting that hexavalent chromium causes lung cancer, and that trivalent chromium, though less toxic, can accumulate in the lungs, which could result in decreased lung function after extended exposure. Following are descriptions of the regulation's requirements:

 

Limit Tank Emissions

Most emissions from chromium electroplating and chromium anodizing baths are found in the fine mists formed by the process. Therefore, reducing mist reduces emissions. This can be achieved through chemical or mechanical control methods. To comply with this NESHAP (see Chrome Emission Limits information below), you may choose from the following control methods:

• Composite mesh pad (CMP) system;
• Packed bed scrubber;
• Fiber-bed mist eliminator;
• Wetting agent-type fume suppressant; and
• Foam blanket.

 

Perform Ongoing Monitoring

Continuous compliance with the regulation is demonstrated through ongoing monitoring of the operating parameters established during initial testing. The monitoring requirements vary depending on the type of emission reduction techniques that you use. (See Monitoring Requirements information below).

 

Establish Work Practice Standards

These standards are better known to industry as Inspection, Operation and Maintenance Plans. Unless a tank is used for decorative plating and contains a trivalent chromium bath with a surfactant, you will need to develop and implement such plans. Here is a brief outline of how to develop them:

• Specify the operation and maintenance criteria for the tank, air pollution control device and monitoring equipment.
• Include a step by step procedure for identifying malfunctions and reporting them to supervisory personnel.
• Specify procedures for preventing malfunctions.

 

Keep Records and Submit Reports

This regulation requires that sources keep records for five years to document compliance. These include inspection records, equipment maintenance records, records of malfunctions and exceedances, performance test results, and monitoring data. If you operate a decorating chromium plating tank that uses a trivalent chromium bath, you only need to keep records of bath component purchases. (A Summary of Reporting Requirements and submission dates are outlined below).

 

Physical Vapor Deposition (PVD)

In this process, a coating material is evaporated, then condensed to a solid onto the work piece. PVD coatings typically have excellent abrasion and corrosion resistance, and satisfactory impact strength, and exhibit higher temperature durability than those applied by electroplating. The process is used in equipment coating applications. Possible drawbacks for small firms include capital costs, quality control issues, and cooling water requirements.

 

High Velocity Oxy-Fuel Thermal Spray Technology (HVOF)

This is a dry process producing dense metallic coatings with physical properties surpassing hard chrome plating. In HVOF, a metal-containing powder is melted and propelled toward the work piece at speeds of up to 4,000 feet per second via carrier gases such as argon. Advantages include a significant volume reduction of: 1) rinse waters, 2) toxic air emissions from chrome-plating bath containers, and 3) hazardous waste streams. Over-spray can be captured and recycled. Drawbacks are similar to PVD system.

 

Cathodic Arc Chromium Coating

Still under development, this technique is designed to produce a high rate of chromium deposition onto a work piece while avoiding the toxic chrome compounds of plating baths. The technique augments the flux to a rate exceeding plating, yet produces low-stress, thick coatings on parts with complicated shapes.

 

Sol-Gel-Derived Composite Coating

By incorporating thermally active organic materials into porous alumina coating, this pre-treatment process for adhesive bonding to aluminum alloys has the potential to eliminate the priming step in conventional anodizing.

Polymer Resist/Masking

The use of a conducting polymer as a replacement for the resist and mask processes can eliminate many chrome-plate preparation steps and wastes. The exposed regions polymerize, permanently adhering to the plate and replacing the chrome. The unexposed monomer can removed with water.

Alodine 2000

Marketed by Parker Amchem, this non-chromate conversion coating has successfully passed performance requirements of MIL-C-5541E/MIL-C-81706 specifications for Class 3 coatings, including corrosion resistance, contact electrical resistance, and paint adhesion.

 

^* Small tanks have a facility maximum potential rectifier capacity of less than 60 million ampere-hours per year. Existing tanks were installed before Dec. 31, 1993.

dynes/cm = dynes per centimeter

mg/dscm = milligrams total chromium per dry standard cubic meter of ventilation air

_____________________________________________________

 

 

 

Through each state in the Northwest, non-regulatory assistance is available for small businesses with air quality questions. The purpose of these programs is to:

• explain the air quality rules and recommend ways to comply;
• provide free, on-site technical assistance visits;
• help businesses estimate their air pollution emissions;
• refer businesses to needed resources; and
• provide information on potential sources of financing for compliance requirements.

For more information and free referrals, contact PPRC.

This fact sheet is intended for general reference only; it is not a complete statement of the technical or legal requirements associated with this regulation.