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.

March 16, 1994

Ms. Charlotte Uram
Landels, Ripley & Diamond Attorneys
Hills Plaza
350 Steuart Street
San Francisco, CA 94105-1250

Dear Ms. Uram:

The purpose of this letter is to correct an interpretation of the Process Safety Management (PSM) of Highly Hazardous Chemicals, 29 CFR 1910.119, standard in the September 9, 1993 letter to you. Question 6 posed in your November 3, 1992 letter and our correction follow. Please replace our original reply to Question 6 with the reply below.

Question 6:

A line fills and packages small containers (one gallon or less) of flammable liquid products that are supplied from a stationary tank that contains more than 10,000 pounds (4535.9 kg) and is located approximately twenty-five feet away. The operation is conducted at both ambient temperature and pressure and in accordance with the requirements of 29 CFR 1910.106. Would the tank be covered under the requirements of the PSM standard?


The described process (storage tanks are considered a part of the process) would be a covered process unless the flammable liquid is stored in an atmospheric tank or transferred and is kept below its normal boiling point without benefit of chilling or refrigeration (See 1910.119(a)(ii)(B)). Please note that in 1910.119(b) the definition of an atmospheric tank means a storage tank which has been designed (emphasis added) to operate at pressures from atmospheric through 0.5 psig (pounds per square inch gauge, 3.45 kpa.) An atmospheric tank containing a flammable liquid that has a feeder connection to the fill process you described would not be covered by the PSM standard. The rationale for this interpretation is that the process described above only included the activities of storage and associate transfer to storage in containers which for the purpose of the PSM standard are considered equivalent to atmospheric tanks which are excepted from PSM coverage as noted previously.

We appreciate your interest in occupational safety and health. If we can be of further assistance, please do not hesitate to contact us.


Roger A. Clark, Director
Directorate of Compliance Programs