26.4. Process Hazard Analysis

Under the “Process Hazard Analysis” requirement of the Process Safety Management of Highly Hazardous Chemicals regulation (29 CFR 1910.119), employers must complete such an analysis of all covered processes using one or more of the following techniques:

• What-If

• Checklist

• What-If/checklist

• Failure mode and effects analysis (FMEA)

• Fault-tree analysis (FTA)

• Hazards and operability study (HAZOP)

or “an appropriate equivalent methodology.” The OSHA regulation specifically refers to the AIChE Center for Chemical Process Safety for details of process hazard analysis methods [9], which is an excellent source for details of these techniques.

The what-if technique involves a group of engineers and others going through the flowsheet and operating procedures methodically and considering what would happen if something were not as expected. For example, What if the reactor were not at the specified temperature? The answers to these hypothetical situations can uncover potential problems. This process hazard analysis technique is normally used only for simple, small-scale processes, such as laboratory experiments. For more complicated processes, the more rigorous HAZOP technique is used. This technique, which is described in the next section, is a formalized version of what-if.