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.

June 1, 1995

Mr. Stephen Z. Short
Bob Short & Associates, Inc.
4849 Greenville Avenue
Suite 1670
Dallas, TX 75206

Dear Mr. Short:

This is in response to your October 24, 1994 letter, requesting an interpretation of the Process Safety Management (PSM) of Highly Hazardous Chemicals standard, 29 CFR 1910.119. Specifically, you requested clarification of section 1910.119(e)(1) on the time allowed for completion of the initial process hazard analysis (PHA) as it may apply to (what you described in your letter as) a hypothetical case involving four different work sites of an employer. Please accept our apology for the delay in responding.

Based on the aforementioned hypothetical case and your belief that natural gas processing plants involve a similar process, you contended in your letter that the employer "could prioritize the four plants based on age, size, number of employees, location, and operating history and complete the requisite process hazard analysis at the plant with the greatest potential for a catastrophic event and then go to the next plant on the priority list, and so on and be in compliance with the 25% rule provided that all work is completed as soon as possible but no later than 1997."

Please be advised that the PSM standard is applicable, on a site by site basis, to each work site, which has one or more facilities containing one or more processes involving one or more of the covered highly hazardous chemicals. A work site may be simply one facility containing a single process. (See the definition of "facility" in Subsection (b) of 1910.119). On the other hand, a work site may be a complex of facilities, each containing one or more processes. By paragraph 1910.119(e)(1), employers are required to perform initial PHA's on processes involving highly hazardous chemicals covered by the PSM Standard. An employer may use a generic process hazard analysis approach for the same (or nearly the same) covered processes. The employer must account for variations (differences in siting, incident histories, technology, equipment, operations, etc.) for each process intended to be included in this generic approach. Generic process hazard analysis is addressed in Section 4 of the nonmandatory, Appendix C, Compliance Guidelines and Recommendations for Process Safety Management in 1910.119.

By paragraph 1910.119(e)(1), all initial PHA's must be completed as soon as possible, with at least 25 percent of them completed by May 26, 1994, 50 percent by May 26, 1995, 75 percent by May 26, 1996 and 100 percent by May 26, 1997. The initial PHA completion requirement applies to all covered processes to which a generic process hazard analysis approach is intended whether generic processes are on the same or different work sites.

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


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