Glossary · Risk estimation methods
Hazard and Operability Study (HAZOP)
Also known as: HAZOP
In safety engineering, a Hazard and Operability Study (HAZOP) is a structured, guideword-based method for examining deviations from the intended operation of a process or system. A multidisciplinary team applies guidewords to process parameters to find hazards and operability problems.
- Machine safety
- Risk assessment
In one sentence
A Hazard and Operability Study (HAZOP) uses guidewords such as “no”, “more” or “reverse” to find hazardous deviations from how a process should run.
Example
A HAZOP of a coolant supply for a CNC line examines “no flow”, “more pressure” and “reverse flow” and finds that loss of flow is not detected before the spindle overheats.
How it applies
- Method: The team divides the system into nodes, then combines guidewords (for example no, more, less, as well as, part of, reverse, other than) with parameters such as flow, pressure, temperature or sequence, and records causes, consequences and safeguards for each credible deviation.
- Machine safety: HAZOP comes from the process industry but also suits machines with process media, such as hydraulic, pneumatic or coolant systems, and integrated systems where the sequence between machines matters.
- Evidence: Findings and actions belong in a hazard log with owners and closure status. The HAZOP record itself documents who took part and which design basis was reviewed.
- Technical documentation: The design intent must be clearly stated before the study. Up-to-date P&IDs, process media specifications and sequence descriptions are prerequisites.
HAZOP vs. FMEA
HAZOP starts from deviations of process parameters and is team-based. FMEA starts from failure modes of individual items. HAZOP finds operational and design-intent problems that component-level analysis can miss.