OSHA requirements are set by statute, standards and regulations. Our interpretation letters explain these requirements and how they apply to particular circumstances, but they cannot create additional employer obligations. This letter constitutes OSHA's interpretation of the requirements discussed. Note that our enforcement guidance may be affected by changes to OSHA rules. Also, from time to time we update our guidance in response to new information. To keep apprised of such developments, you can consult OSHA's website at http://www.osha.gov.

January 28, 1992

MEMORANDUM FOR:     LINDA ANKU
                   REGIONAL ADMINISTRATOR

THROUGH:            LEO CAREY, DIRECTOR 
                   OFFICE OF FIELD PROGRAMS

FROM:               PATRICIA K. CLARK, DIRECTOR 
                   DIRECTORATE OF COMPLIANCE PROGRAMS

SUBJECT:            Need for Flashback Arrestors and Backflow Protective
                   Equipment for Welding Operations

This is a further response to your memorandum of October 4, 1991, in which you sought guidance as to when flashback arrestors and backflow protective equipment are required in fuel-gas supply systems, in keeping with the requirements of 29 CFR 1910.253, Oxygen-fuel gas welding and cutting. In your memorandum, you also stated that a representative of the American Welding Society (AWS) informed OSHA personnel that the AWS no longer requires these protective devices, which are no longer included in their standards. Please excuse the delay in our response.

We reviewed the latest ANSI Z49.1-1988 standard and noted that protective equipment devices for service piping systems were eliminated; however, paragraph 1.3 of the above standard (attached) stated that those requirements were only deleted from ANSI Z49.1-1988 to avoid their being included in two separate standards under separate auspices. The paragraph also stated that the protective devices are still considered necessary and important for safety, and therefore the requirements must be followed. The requirement for protective devices are contained in the list of ANSI/NFPA standards found in paragraph F1.3 of ANSI Z49.1-1988 (attached).

The removal from ANSI Z49.1-1988 of the requirements for protective devices does not warrant a change in the OSHA requirements. The Agency will continue to enforce the requirements of 29 CFR 1910.253(e).

We appreciate your time and effort in bringing this matter to our attention. If you have additional questions, please feel free to contact James C. Dillard, of my staff, at FTS 523-8041.