Per OSHA and per CCPS, a PHA is the risk analysis for the unit for all modes of operation. CSB has been really hitting hard lately as well. (See the Bayer CropSciences report for a good example.) The most critical part of that analysis is the portion for startup, shutdown, and online maintenance, since 80% of major accidents occur during those modes of operation. Nowhere does OSHA or anyone say that a PHA is only for normal modes of operation. In fact – OSHA, CSB and CCPS have emphasized that a PHA is required for all modes of operation. Unfortunately, regulation in the US is dismally weak in general. Also unfortunately, there have been a lot of folks that mistakenly learned the wrong lessons about PHAs; they follow bad art and believe that the “real” PHA is only part of the NORMAL mode of operation. In many processes, that is the mode that needs the least focus in a PHA.

A revalidation also covers ALL modes of operation, so normal and non-routine modes would be revalidated.

How you do revalidations is a whole different topic; the approaches depend on many factors related to the thoroughness of the previous PHA(s) and the clarity of the previous PHA.

Annual certification of procedures is required, as mentioned. But the accuracy of the procedures is not what a PHA is about. We do not do a PHA of procedure to improve the accuracy of the procedures or validate the accuracy and completeness. The PHA of non-routine modes of operations is about using the procedure as a springboard for discussion about “the scenarios that occur when the operator makes a mistake (1/100 likelihood, minimum) in following the procedure, even if the procedure is perfect!” Assuming a PHA of non-routine modes (based on procedures as the springboard for discussion, rather than P&IDs) does not need to be revalidated if the procedures are kept accurate is the same as assuming the PHA of normal mode does not need to be revalidated if the P&IDs are kept accurate.

The purpose of revalidation is mainly to be a safeguard against omissions in previous PHAs, including against omissions in the mini-PHA of each change to a procedure and each change to the design, etc.

If you want to learn more about how to do a revalidation, let us know… we have performed many hundreds of them.

There is a good paper on the portion of the PHA related to non-routine modes of operation on our website:

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