For years, many companies involved in welding and other metalworking operations have exhausted fumes and dust outside. The U.S. Environmental Protection Agency’s (EPA) recently enacted Rule 6x regulation for managing hazardous air pollutants is changing that practice. Following here is a summary of the impact of EPA Rule 6x, how to determine whether your operation is impacted, the actions that you may be required to take, and control strategies.

Development of air emission standards
The 1990 Clean Air Act required the EPA to develop air emission standards for a list of 187 hazardous air pollutants (HAPs). The standards are enforced to reduce exposure to HAPs because the chemicals are known to cause cancer or other serious health effects, such as birth defects.

The EPA introduced its National Emission Standard for Hazardous Air Pollutants (NESHAP) in 2008. Within this standard are the HAPs that apply to the metal fabrication industries – known as Metal Finishing Hazardous Air Pollutants or MFHAPs. These are defined as materials that contain 0.1% by weight cadmium, chromium, lead, or nickel; or 1.0% by weight manganese. Manganese is the material of widest concern to the welding industry, as it is virtually a universal component of welding wire.

Who is affected by Rule 6x
How do you know if your operation is using these materials? As a starting point, consult the Manufacturing Safety Data Sheets (MSDS) for the base materials that you are using – e.g. welding rod, welding wire, etc. A standard MSDS will list hazardous ingredients in Section 2. If, for example, the material is shown to contain <2.50 percent manganese by weight, the material is subject to the NESHAP 6x rule (Figure 1).

The rule applies to companies that are primarily engaged (defined as 50 percent or more of total labor) in one or more of the following categories: electrical and electronic equipment finishing, fabricated metal products, fabricated plate work (boiler shops), fabricated structural metal manufacturing, heating equipment (except electric), industrial machinery and equipment finishing, iron and steel forging, primary metal products manufacturing, and valve and pipe fittings (Figure 2).

Operations that are impacted by the rule cover eight processes: dry abrasive blasting (three types), dry grinding, dry polishing with machines, dry machining, spray painting (two types) – and last but not least, welding (Figure 3).

Exceptions to the rule include military installations; NASA facilities; national nuclear security facilities; military munitions facilities; research or laboratories as defined in the Clean Air Act; tool, quality control and equipment repair facilities; and welding facilities using less than 2,000 lbs. of rod or wire that does not contain any identified HAPs (per the MSDS).

Your plant is likely to be impacted if you: (a) are in one of the industry categories listed above; (b) are primarily engaged in one of the processes identified above; (c) exhaust the air straight outdoors; and (d) fail an EPA Method 22 Fugitive Emission test.

Method 22, which is conducted to provide a visual determination of fugitive emissions from material sources, is performed by a trained observer who monitors an exhaust stack during a 15-minute timed test. If opacity – defined as the quality of a particle that makes it impervious to light – is observed during 20 percent or more of the test (i.e., three minutes), then Rule 6x applies. Involvement of an environmental engineering consultant is recommended to conduct the Method 22 test and provide third-party confirmation of whether a facility is in compliance.