What HAZOP covers
A Hazard and Operability Study (HAZOP) is a systematic, multidisciplinary review of how a process can deviate from design intent and what those deviations could cause.
Teams typically examine five deviation domains:
- Flow and inventory deviations (no flow, low flow, reverse flow, overfill).
- Pressure and temperature deviations beyond design envelope.
- Composition and contamination deviations (wrong material, dilution, impurity).
- Phase and physical state deviations (unexpected vaporization, condensation, solids).
- Timing and sequencing deviations during startup, shutdown, and abnormal operations.
Timing and governance
Most projects run HAZOP during detailed design (roughly 60-80% complete) or before commissioning. At this point, documentation is mature enough for meaningful analysis and there is still time to implement changes.
The method is commonly aligned to IEC 61882 and mapped into local process safety requirements and management-of-change workflows.
Expected outputs
A high-quality HAZOP should produce structured deliverables, not just meeting notes:
- Node-by-node deviation records with causes, consequences, and existing safeguards.
- Residual risk judgement and recommendation rationale.
- Action register with owners, due dates, and closure evidence.
- Pre-startup verification trail confirming critical safeguards are in place.
Manual versus digital execution
Spreadsheet-led studies often lose context and closure discipline. Digital HAZOP workflows improve consistency by standardizing data capture, linking findings to change management, and surfacing overdue actions automatically.
Common pitfalls to avoid
- Starting before design data is mature enough to support credible decisions.
- Running sessions without operations or maintenance representation.
- Treating action tracking as optional after workshop closeout.
- Allowing facilitator bias to narrow the scope of challenge.