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.

September 20, 1993

Mr. Michael D. Zoll
Manager of Safety
Alcan Aluminum Corporation
100 Erieview
Cleveland, Ohio 44114-1878

Dear Mr. Zoll:

This is in response to your July 30 letter, requesting interpretation of the Process Safety Management (PSM) of Highly Hazardous Chemicals standard, 29 CFR 1910.119. Please accept our apology for the delay in responding. In your letter you requested clarification on whether the PSM standard applies to the process described in the following scenario.

An aluminum rolling mill contains an aluminum sheet coating line. Aluminum sheet is passed through a piece of equipment that puts a film of flammable liquid paint on the sheet. The entire system holds less than 200 gallons (757 liters) of paint well below the 10,000 pounds (4535.4 kg) threshold quantity. The coating line is connected by a pipeline to a storage room where flammable coatings are mixed and stored in atmospheric tanks.

The storage room, the coating equipment and the connecting piping are considered a single process. Please refer to the definition of process at 1910.119(b). When collectively containing threshold quantities or greater amounts of flammable liquids, this coating process is covered by 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