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 25, 1995

Don C. Wobser
MTI Corporation
2 Smiley Drive
St. Albans, WV 25177-8221

Dear Mr. Wobser:

This is in response to your March 31, 1995 letter requesting clarification of the Process Safety Management standard (PSM), 29 CFR 1910.119, with regard to material and energy balances as required by paragraph 1910.119(d)(3)(i)(G). The work place scenario you describe concerns modifications to existing facilities, built significantly before the effective date of the standard, to raise the capacity 150% above original.

There is insufficient information in the scenario to permit an exact response to your questions at this time. New processes, those built after the effective date of the standard, are required to have material and energy balances calculated as part of the required Process Safety Information. In your letter, you state that the facility was substantially built before the effective date of the standard. There is no indication whether the process was started before or after May 26, 1992. In addition, there is no information regarding how the 150% increase in capacity would be accomplished. If a new line, unit, or "train" is added to supplement the process, these could be considered new processes requiring material and energy balances. If the increase in capacity is accomplished through new or different chemistry, such as a chemical reaction in place of a unit physical operation, this would be a new process requiring the material and energy balance calculation.

If the capacity increase is due to process changes made to existing equipment and/or chemistry, such as increase/decrease in flows, temperatures, pressures etc., or efficiency gains, these modifications would not constitute a new process, and would not be required to have a material and energy balance. These modified processes would be subject to all of the PSM requirements including Management of Change, and Pre-startup safety review, paragraphs 1910.119(l) & (i), respectively.

We appreciate your interest in occupational safety and health. If we can be of further assistance, please contact Ron Davies of my staff at (202)219-8041.


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