What is a what-if analysis?
What-if analysis is the most accessible hazard identification method: a facilitated conversation guided by "what if…?" questions. It works especially well for changes, where a short review before implementation prevents surprises. For more structure on a process plant, use HAZOP; to rank and communicate the resulting risks, use a risk matrix.
What-if question checklist
- Equipment: what if it fails, stops, leaks, runs too fast or too slow?
- People: what if a step is skipped, done in the wrong order, by an untrained person, or at night?
- Materials: what if the material is wrong, contaminated, missing or out of specification?
- Utilities: what if power, compressed air, water or IT systems are lost?
- Environment: what if it is very hot, cold, wet, icy or dark?
- Maintenance and change: what if work is done while the process runs, or a temporary change becomes permanent?
What-if analysis example
The example reviews warehouse loading dock operations. "What if a truck pulls away while a forklift is inside the trailer?" is the highest risk (severity 5, likelihood 3): manual wheel chocks are the only safeguard, so the team recommends a vehicle restraint interlocked with the dock door, which brings the residual risk to medium. Pallets stacked too high stay high after floor markings, and need a further action. Icy docks drop to low with scheduled gritting and heated dock plates.
Choosing a hazard identification method
| Method | Best for | Effort |
|---|---|---|
| What-if | Simple processes, changes, procedures | Low |
| PHA | Early system design | Low to medium |
| FMEA | Components and process steps | Medium |
| HAZOP | Process plants with P&IDs | High |
How to use this What-If Analysis tool
- Define the scope. Name the process, area or change and the boundaries of the review.
- Ask what-if questions. Go step by step and write each "what if…?" question in the worksheet.
- Record consequences and safeguards. Note what would happen and which safeguards already exist.
- Rate the risk. Rate severity and likelihood with the existing safeguards, or drag the markers on the matrix.
- Recommend and assign. Add recommendations and owners, and rate the residual risk once they are in place.
- Export. Export the analysis and the risk matrix to PDF or Excel.
Frequently asked questions
What is a what-if analysis?
A what-if analysis is a structured brainstorming method in which a team asks "what if…?" questions about a process, system or change, for example "what if the cooling water fails?". For each question the team records the consequences, the existing safeguards, the risk and any recommendations.
When should I use what-if analysis?
It suits simple to moderately complex processes, changes (management of change), new procedures and non-routine tasks, and situations where a full HAZOP would be too heavy. It is quick to learn and needs no special technique beyond experience and good questions.
How do I generate good what-if questions?
Walk through the process step by step and consider equipment failure, human error (wrong, missed or late actions), utilities (power, air, water), materials (wrong, contaminated, missing), external events (weather, traffic) and maintenance. Combining what-if with a checklist (what-if/checklist analysis) makes it more complete.
What is the difference between what-if and HAZOP?
What-if relies on the team's questions and is fast and flexible. HAZOP applies guidewords to every parameter of every node, which is more systematic and thorough but takes much longer. For high-hazard processes, HAZOP is generally expected.
Who should take part?
People who know the process from different angles: operators, supervisors, maintenance, engineering and EHS, with a facilitator who keeps the questions flowing and a scribe.