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Atmospheric tank storage under the process safety rule

Summary A chemical company asked whether flammable liquids kept in atmospheric tanks above the threshold quantity were outside the process safety rule. OSHA said the storage method alone did not establish an exception. A tank could still be covered if it formed part of a covered process or sat near a hazardous process where a catastrophic event could involve it.
Document
Federal opinion letter
Agency
Occupational Safety and Health Administration (OSHA)
Document number
1992-08-21-2
Date issued
August 21, 1992
Status
Archived by the agency
OSHA marks this page as an archive document and says it may no longer represent OSHA policy.
Status last verified October 9, 2026

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NOTICE: This is an OSHA Archive Document, and may no longer represent OSHA Policy. It is presented here as historical content, for research and review purposes only.

August 21, 1992

Mr. Leslie A. Scher
Director of Risk Management
Grace Specialty Chemicals Company
[Recipient address omitted]
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.

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

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