A critique of the Hazard and Operability (HAZOP) study

• The HAZOP study suffers from various weaknesses, many of which are not generally recognized.
• Knowledge of the weaknesses will enable study teams to compensate for them to the extent possible following guidance provided.
• Knowledge of the weaknesses can help to guide the development of improved PHA methods.

Conventional wisdom holds that the Hazard and Operability (HAZOP) study is the most thorough and complete process hazard analysis (PHA) method. Arguably, it is the most commonly-used PHA method in the world today. However, the HAZOP study is not without its weaknesses, many of which are not generally recognized. This article provides a critique of the method to assist study teams in compensating for them to the extent possible and to help guide the development of improved methods.