Archive Notice - OSHA Archive

NOTICE: This is an OSHA Archive Document, and may no longer represent OSHA Policy. It is presented here as historical content, for research and review purposes only.

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

August 21, 1992

Mr. Leslie A. Scher
Director of Risk Management
Grace Specialty Chemicals Company
One Town Center Road
Boca Raton, Florida 33486-1010

Dear Mr. Scher:

This is in response to your letter of August 14, and our subsequent meeting on August 18, regarding 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 26, 1992. In your letter you asked for an interpretation on the applicability of the PSM standard to a number of different processes you described involving flammable liquid stored at atmospheric pressure at or above the threshold quantity of 10,000 pounds.

The method of storage of flammable liquids is but one consideration which must be evaluated to determine whether or not a flammable liquid at or above the threshold quantity is subject to the PSM standard. Merely to store a flammable liquid in tanks at atmospheric pressure is not in itself sufficient reason to remove a facility from coverage. Although the standard provides a conditional exception for such storage, such substances are covered if, for example, they are part of a "process", as defined in the standard, or if they are sited in near proximity to a hazardous process and thus might become involved in a catastrophic event.

As we discussed, interpretations are being developed on the new standard, including section 1910.119(a)(ii), which deals with the rules's scope of application. When completed, those interpretations will be included in a PSM directive, which will be made available to the public. We will provide you with a copy of the PSM directive, when it is published, which is tentatively scheduled for next month.

I hope this response will assist you in preparing for your upcoming seminar. If you have further questions, please let me know.


Raymond E. Donnelly, Director
Office of General Industry Compliance Assistance