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.

June 9, 1993

Mr. Gary Stubblefield
Senior Technician
Petrocon Engineering, Inc.
P.O. Box 20397
Beaumont, Texas 77720-0397

Dear Mr. Stubblefield:

This is in response to your letter of June 12 to Mr. Gilbert J. Saulter, Dallas Regional Administrator for the Occupational Safety and Health Administration. Your letter was forwarded to the Directorate of Compliance Programs for response. Please accept our apology for the delay in responding.

In your letter you requested an interpretation on the Final Rule on Process Safety Management (PSM) of Highly Hazardous Chemicals published in Volume 57, Number 36 of the Federal Register on Monday, February 24 1992. In particular, you sought clarification on whether black liquor recovery boilers and/or associated oil- or gas-fired auxiliary fuel burner systems are subject to the PSM Standard.

Black liquor recovery boilers involving a PSM-covered chemical at or above threshold quantity are covered by the PSM Standard. Gas-fired auxiliary fuel burner systems are covered by the PSM standard when used to fire black liquor recovery boilers involving threshold or greater quantities of another covered chemical. Gas-fired auxiliary fuel burner systems would not be covered by the PSM Standard when used to fire black liquor recovery boilers involving less than threshold quantities of another covered chemical.

Also, threshold and greater quantities of stored flammable liquids or gases are covered if they could be involved in a release in another covered process, for example, a black liquor recovery boiler, sited nearby.

Thank you for your interest in occupational safety and health. If we may be of further assistance, please contact us.

Sincerely,



Roger A. Clark, Director
Directorate of Compliance Programs