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OSHA Interpretations: Process Boundaries |
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As a result of a 1997 PSM inspection of a covered facility in Region 2, OSHA published an internal memo on how to determine how far a covered process extends. This memo explores the situation where covered chemicals can migrate to portions of the process and other equipment where they are not normally expected and thus extend the boundaries of a PSM program. Specifically, employers must: 1. Determine the extent of process(es) by utilizing the definition of process [1910.119(b)] which includes any vessels which are connected and separate vessels located such that a HHC could be involved in a potential release. Engineering and administrative controls required by the PSM standard to prevent catastrophic release of a covered HHC may not be used to determine the extent of a process as defined in paragraph 1910.119(b) (emphasis added). This interpretation is predicated on the assumption that an event such as an explosion will take place in the process notwithstanding such controls. 2. Determine whether the process contains at any particular time a threshold quantity (TQ) or greater amount of a PSM HHC. If so, the process is covered by the PSM standard. 3. Consider each aspect of the process as defined to determine the extent of PSM coverage for each particular aspect. Aspects of the process which contain a HHC would be covered by all PSM elements, such as information, process hazard analysis and mechanical integrity. Aspects which do not contain HHC, but are interconnected or located nearby are part of the process. Such aspects may or may not be covered by the PSM standard based on whether the particular aspects could cause a HHC release or interfere with mitigating the consequences if there was a HHC release. If the particular aspects do not contain a HHC but could cause a HHC release or interfere with mitigating the consequences of a HHC release, then based on the employer's analysis, various elements of PSM would apply to these aspects; If based on this analysis, it is determined that interconnected equipment downstream from the stipulated covered process cannot cause a HHC release or interfere with the mitigation of the consequences of a HHC release, and the equipment does not itself contain a TQ or greater amount of a HHC, then such equipment could safely be considered outside the limits or boundaries of the covered process. For example, if a batch process normally would consume covered materials in a reactor, but active safeguards are relied upon to ensure that the reaction goes to completion, then a downstream product storage tank might be also have to be included in the PSM program if a threshold quantity or more could migrate to the tank in a unreacted state. If the completion of the reaction relies only on passive safeguards, then the downstream equipment might be exempt from PSM coverage. For more information on this particular interpretation, see OSHA internal memo dated February 28, 1997. To read about Interpretations about the Treatment of Utilities, click here. To go back to Part 1: OSHA Interpretations, click here. Go to AcuSafe.
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