Final answer:
A process hazard analysis (PHA) should be updated when major changes are made to the process, but periodic reviews and updates are also recommended.
Step-by-step explanation:
A process hazard analysis (PHA) is an evaluation of potential hazards involved in a process, such as a chemical manufacturing or refining process. It is typically conducted to identify and assess risks associated with the process and to determine appropriate safety measures.
The frequency of updating a PHA may be specified by regulations or industry standards, depending on the type of process and the jurisdiction. Generally, a PHA should be updated whenever major changes are made to the process, such as modifications to equipment, operating procedures, or the introduction of new hazardous chemicals.
However, it is good practice to periodically review and update the PHA even if no major changes have been made, as new information or insights may arise that could enhance the safety of the process.