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 https://www.osha.gov.

January 8, 1993

Mr. Garry 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 18, to Mr. Gilbert J. Saulter, Dallas Regional Administrator for the Occupational Safety and Health Administration (OSHA). 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 when steam boilers fired by flammable liquids or natural gas are subject to compliance with the PSM Standard. You requested clarification with respect to facilities which use hydrocarbon fuels delivered via pipeline from outside sources.

The PSM standard applies to flammable liquids and gases in quantities of 10,000 pounds (4535.9 kg) or more. There are two exceptions. First, a hydrocarbon fuel (any quantity) used solely for workplace consumption as a fuel, if such a fuel is not a part of a process containing a threshold quantity or greater amount of another highly hazardous chemical, is not covered by the PSM standard. Secondly, flammable liquids stored in atmospheric tanks or transferred (for storage) which are kept below their boiling point without benefit of chilling or refrigeration are not covered by the PSM standard. However, flammable liquids or gases used in a (boiler) system which is part of a process containing a threshold quantity or greater amount of another highly hazardous chemical are covered by the PSM standard.

You expressed concern in your letter that an incident at a worksite could result in a catastrophic release of a threshold quantity or greater amount of a flammable fluid supplied from an outside source, and you requested an interpretation on the applicability of the PSM standard to this worksite application. The applicability of the PSM standard is determined with respect to each worksite, on a site by site basis. The PSM Standard applies to boiler, furnace or heater systems fired by natural gas provided by pipeline from an outside source if there is any amount of natural gas in any one of these systems when it is part of a process containing a threshold quantity or greater amount of another highly hazardous chemical covered by the PSM Standard. A boiler used to provide heat to a process covered by the PSM Standard is considered part of the covered process.

The paragraph above discuss processes covered by the PSM Standard. When a process hazard analysis (as required in paragraph (e) of the PSM Standard) is performed, it must consider the potential release of gas from the pipeline into the facility, as you mentioned near the end of your letter.

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