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 14, 1995

James B. Evans
Union Carbide Corporation
39 Old Ridgebury Road, K3
Danbury, Connecticut 06817-0001

Dear Mr. Evans:

This is in response to your June 1, 1994 letter requesting interpretation of the Process Safety Management standard 29 CFR 1910.119. Your question concerns the term "interconnection" as it would apply to utilities, steam and electric, used in a covered process.

Utilities that serve a covered process are considered part of the process where they can impact on, or affect a release of the highly hazardous chemical in the process. Utility system failure such as loss of instrument air, heating and cooling mediums, and electric have been a major cause of upset conditions in chemical processes. These utility systems would be subject to all of the provisions of the PSM standard until such point where a failure in component of the system can no longer affect a potential release of a covered chemical, or where the utility leaves the control of the employer.

Enclosed is a letter of interpretation which may provide additional help.

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


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