PSM coverage of interconnected flammable-liquid processes

NOTICE: This is an OSHA Archive Document, and may no longer represent OSHA Policy. It is presented here as historical content, for research and review purposes only.

November 3, 1995

Mr. Paul J. Lawonn
MRA-The Management Association, Inc.
[Recipient address omitted]
Dear Mr. Lawonn:

This is in response to your September 15 letter requesting an interpretation of the Process Safety Management (PSM) of Highly Hazardous Chemicals (HHC's) standard, 29 CFR 1910.119. Specifically, you requested clarification as to whether the three processes enclosed with your letter would be covered by the PSM Standard. Your process diagrams are enclosed to facilitate our response.

Process A The use of the hose connection as depicted in the enclosed process A diagram would not preclude this process from being covered by the PSM standard. Delivery of flammable liquid from the atmospheric tank to fill "a portable tank or nearby stationary tank" is considered an onsite movement activity which precedes the handling and use activities of the coating operation. Under the paragraph 1910.119(b) definition of process, the coating operation, including the activities of on-site movement, handling or use, interconnected by way of a hose connection to the flammable liquid atmospheric storage tank is considered a single process. When such a process contains a threshold quantity, that is, 10,000 pounds (9545 kg) or greater amounts of a cover HHC at any one point in time, it is covered by the PSM standard. This interpretation is predicated on the assumption that an event, such as a fire or explosion, will take place notwithstanding engineering (including fusible link check valve) controls and administrative controls required by the PSM standard to prevent a catastrophic release of the HHC.

Process B There is insufficient information on Process B to determine whether this process would be covered by the PSM standard. The process depicted in the Process B diagram would not be covered, under the paragraph 1910.119(a)(1)(ii)(B) exception, when located away from any other HHC process such that there is no reasonable probability that an event such as an explosion in other vessels which contain quantities of the chemical that when added together would exceed the threshold and provide a potential for a catastrophic release. (F.R. 6372)

Process C As explained in the Process A reply above, the use of engineering controls such as those used in the transfer of flammable liquid from the (atmospheric) storage tank to the (atmospheric) process tank as described for Process C would not preclude this process from coverage by the PSM standard.

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

Sincerely,
John B. Miles, Jr., Director
Directorate of Compliance Programs

[Requester-supplied process descriptions reproduced on OSHA page; omitted here.]