Glossary term
Hazard and Operability Study (HAZOP)
Subject: Risk Management, Risk Assessment and Quantification
Also known as: HAZOP, Hazard and operability analysis
HAZOP is a structured team review of an industrial process design, in which guide words such as no, more or less are applied to each step to find hazards and operating problems.
Explanation
A cross-functional team, usually with process engineers, operators and safety staff, works through a plant design section by section. For each section it names the intended behaviour, such as a flow of liquid through a pipe. It then applies guide words (no, more, less, reverse, other than) to parameters like flow, pressure and temperature. Each deviation is discussed: what could cause it, what would happen, whether existing safeguards are adequate, and what action is needed. A scribe records everything in a table. HAZOP is used in chemicals, oil and gas, pharmaceuticals and power, normally at design stage and again when a plant changes. It depends on experienced people and takes time. Fixing a flaw on the drawing costs far less than fixing it after an accident.
Example
A chemical plant plans a new reactor feed line. During the review, the guide word “more” applied to temperature raises the question of a runaway reaction if cooling fails. The team finds the only alarm shares a power supply with the cooling pump and adds a separate alarm and an automatic shutdown.
Not to be confused with
- Failure Mode and Effects Analysis
- FMEA examines equipment or component failures. HAZOP examines deviations from intended process operation using guide words.