Hazard and Operability (HAZOP) Studies

A Hazard and Operability (HAZOP) study is a technique which generally focusses on hazard identification through a combination of both causal analysis and consequence analysis.

A HAZOP study looks at the flow of either information or material around a system. Possible deviations from intended flow are identified (on the basis of customised guidewords) and studied for possible causes and consequences.

The intepretation of the guidewords varies widely depending upon the flow being discussed, e.g., "too much" supply of a chemical flow may be quite different from "too much" information.

As with a Failure Modes and Effects Analysis (FMEA), although HAZOP studies can be thorough, they can suffer from repetitiveness and inappropriate choice of guidewords or level of flows.


The Longford Esso gas plant explosion may have been prevented if this form of hazard identification had been performed.