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.

April 28, 1993

Ms. Carol S. Miller
Safety Coordinator
Research and Development Laboratories
P.O. Box 2726
Baton Rouge, Louisiana 70821

Dear Ms. Miller:

This is in response to your March 29 letter requesting clarification on the applicability of the Process Safety Management (PSM) of Highly Hazardous Chemicals standard, 29 CFR 1910.119, to flammable liquid stored on your worksite.

The process described in your letter which includes the activities of storage and associated transfer of a large quantity, that is, 10,000 pounds (4535.9kg) or more of naphtha which is maintained under a dry nitrogen pressure of 8-10 psig (55.2-69 kpa) is subject to the PSM standard.

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


Roger A. Clark, Director
Directorate of Compliance Programs