OSHA PSM Citation Summary


		AcuSafe Home Page -> January 2002 Newsletter
		OSHA Interpretations: Interfacing Utility Systems

Interpretations of the PSM Standard regarding Interfacing Utility Systems

The following utility interpretations of the PSM Standard have been paraphrased and summarized for ease of reading and for space considerations in this article. The exact wording, including fuller explanations by OSHA made be found in the actual documents referenced.

Question: The term "interconnection" as it would apply to utilities, steam and electric, used in a covered process. Answer: 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. (OSHA letter of 9/14/95 - first letter)
Question: A utility system (e.g. steam or cooling water) is connected to a PSM covered process and supplies the process with either heat or cooling. During the process hazard analysis, it was determined that the failure or upset of the utility system has no adverse effect on the process. Is the utility system in this case also to be considered a covered process? Answer: A utility system connected to a PSM covered process would have to be addressed in the Process Hazard Analysis. You note that the Process Hazard Analysis indicates that the utility system has no adverse effect on the process. Nonetheless, the utility system, as described above, continues to be a consideration in a covered process. For example, modifications may be made to a process that might change the impact of the utility on the process. Additionally, if you have several covered processes served by the utility system, then you would have to consider the impact of the utility system in the Process Hazard Analyses of those processes as well. (OSHA letter of 3/10/94)
Question: Would the powerhouse boiler, the on site portion of the gas pipe line and the production unit be considered one process, due to interconnection? Answer: If the natural gas were used as a feed stock rather than a fuel in the unit furnace, the unit furnace and interconnecting pipe on site would be a single process. The powerhouse boiler would be included if it were connected to the same on site piping as the unit furnace. In any event, the boiler would have to be reviewed in any hazard analysis with respect to loss of this utility function and its impact on the process. (OSHA letter of 9/14/95 - second letter)
Question: Are steam boilers fired by flammable liquids or natural gas are subject to compliance with the PSM Standard? Are facilities which use hydrocarbon fuels delivered via pipeline from outside sources covered by PSM? Answer to first question: The PSM standard applies to flammable liquids and gases in quantities of 10,000 pounds (4535.9 kg) or more. There are two exceptions. First, a hydrocarbon fuel (any quantity) used solely for workplace consumption as a fuel, if such a fuel is not a part of a process containing a threshold quantity or greater amount of another highly hazardous chemical, is not covered by the PSM standard. Secondly, flammable liquids stored in atmospheric tanks or transferred (for storage) which are kept below their boiling point without benefit of chilling or refrigeration are not covered by the PSM standard. However, flammable liquids or gases used in a (boiler) system which is part of a process containing a threshold quantity or greater amount of another highly hazardous chemical are covered by the PSM standard. Answer to second question: The applicability of the PSM standard is determined with respect to each worksite, on a site by site basis. The PSM Standard applies to boiler, furnace or heater systems fired by natural gas provided by pipeline from an outside source if there is any amount of natural gas in any one of these systems when it is part of a process containing a threshold quantity or greater amount of another highly hazardous chemical covered by the PSM Standard. A boiler used to provide heat to a process covered by the PSM Standard is considered part of the covered process. (Note added: It takes approximately 10 miles of 4 in piping to reach 10,000 of natural gas at typical distribution pressures of about 200 psig). (OSHA letter of 1/8/93)
Question: Are black liquor recovery boilers and/or associated oil or gas fired auxiliary fuel burner systems are subject to the PSM Standard? Answer: Black liquor recovery boilers involving a PSM covered chemical at or above threshold quantity are covered by the PSM Standard. Gas fired auxiliary fuel burner systems are covered by the PSM standard when used to fire black liquor recovery boilers involving threshold or greater quantities of another covered chemical. Gas fired auxiliary fuel burner systems would not be covered by the PSM Standard when used to fire black liquor recovery boilers involving less than threshold quantities of another covered chemical. Also, threshold and greater quantities of stored flammable liquids or gases are covered if they could be involved in a release in another covered process, for example, a black liquor recovery boiler, sited nearby. (OSHA letter of 6/9/93)
Question: Would the use of an Instrument Society of America (ISA) Standard S91.01 would be appropriate for determining which controls are covered by the Mechanical Integrity paragraph? Answer: Equipment covered in this list is considered critical to process safety because of its potential for significant impact on the safety of a process involving highly hazardous chemicals if it did not maintain its mechanical integrity. If an employer deems additional equipment to be critical, it too should be considered to be covered by §1910.119(j) and should be treated accordingly. (emphasis added). Therefore, your records should assure a written Mechanical Integrity Program for all named equipment. The ISA Standard that you have referenced only addresses two categories of process safety equipment of those which are listed in 1910(j)(1). The categories addressed are listed in §1910.119(j)(1)(iv) and (j)(1)(v) (emergency shutdown systems and safety critical controls, respectively.) (OSHA letter of 12/7/95) Note added: That OSHA answered this question within the context of the applicability of the mechanical integrity element of PSM to certain types of interfacing instrumentation and controls equipment. However, OSHA's response is interesting in that they seem to indicate that any equipment that is deemed critical to process safety - some utilities clearly fall into this category - should be covered by the MI program. This might indicate that the remainder of the PSM should also be applied as it finds at PSM-covered sites and with published GEPs. OSHA also said that the basis for deviating from GEPs should be documented. (VPP Participant's Association Conference, September 1995)

If you have an interpretation that you would like to share with AcuSafe or feedback about this feature, please email us at editor@acusafe.com. To go back to the OSHA Interpretations Feature Index, click here or go back to AcuSafe.