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NOTICE: This is an OSHA Archive Document, and may no longer represent OSHA Policy. It is presented here as historical content, for research and review purposes only.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

December 8, 1995

Mr. William J. Schuchman
Executive Director
Metropolitan Manufacturers' Association
10733 Big Bend
St. Louis, MO 63122-6027

Dear Mr. Schuchman:

This is in response to your September 20, 1994 letter requesting an interpretation of the process safety management (PSM) of highly hazardous chemicals standard, 29 CFR 1910.119. Specifically, you requested clarification on the exception under paragraph 1910.119(a)(1)(ii)(B) as it applies to flammable liquids stored in atmospheric tanks or transferred which are kept below their normal boiling point without benefit of chilling or refrigeration. Please accept our apology for the long delay in responding.

The exception under paragraph 1910.119(a)(1)(ii)(B) is applicable to a process that only includes the activities of storage and associated transfer of flammable liquids under the conditions noted above. This exception would not be applicable to a process which includes any one or combination of the following flammable liquid activities: use, storage (other than described previously), manufacturing, handling, or on-site movement and also storage in atmospheric tanks and associated transfer which are kept below their normal boiling point without the benefit of chilling or refrigeration. See the definition of process under paragraph 1910.119(b). For the purposes of this definition, any group of vessels which are interconnected and separate vessels which are located such that a highly hazardous chemical, including a flammable liquid, could be involved in a potential release are considered a single process.

We appreciate your interest in occupational safety and health. If we can be of further assistance, please contact Mr. Ronald J. Davies of my staff at telephone (202) 219-8031, extension 110.


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