HAZOP studies generate a lot of paperwork. For a mid-size capital project — a new unit addition, a greenfield petrochemical facility, a refinery expansion — a thorough study might produce 80 to 200 action items. A complex facility with multiple process units can easily reach 400 or more.
The study itself gets the attention. Teams spend weeks preparing, facilitators are brought in, leadership reviews the final report. Then the project moves into detailed engineering, schedules compress, and the action item register gets handed off to an engineer who has seventeen other things to manage.
That's where incidents come from.
"The HAZOP is where you find the hazards. The action register is where you decide what to do about them. Most projects nail the first part and fumble the second."
Why HAZOP Actions Close Late — or Don't Close at All
It isn't usually negligence. The patterns are predictable:
Actions get assigned without acceptance criteria. "Review relief device adequacy" is not an action. It's a topic. An action needs a specific deliverable, a responsible engineer, and a defined standard for completion. Without these, close-out becomes a judgment call — and under schedule pressure, the judgment tends to favor closing.
The register lives in the HAZOP software, not in the project management system. HAZOP software is excellent for conducting studies. It's rarely integrated with the engineering workflow. Action items sit in a separate tool that the structural engineer, the project controls team, and the construction manager don't look at.
Actions span disciplines, but ownership doesn't. A single HAZOP recommendation might require a process engineer to revise a P&ID, an instrument engineer to add a high-high trip, and a civil engineer to verify drainage grades. When responsibility isn't clearly assigned at the discipline level, everyone assumes someone else is handling it.
Late design changes reopen closed items. An action item gets resolved, documented, and closed. Six weeks later, a vendor change or a scope modification affects the same section of the design. If there's no process for identifying which closed HAZOP actions are affected by design changes, the resolution is invalidated without anyone knowing.
What a Working Register Actually Looks Like
A functioning HAZOP action register has six fields per action. Not three, not ten. Six:
| Field | What It Contains | Why It Matters |
|---|---|---|
| Action ID | Unique, sequential (e.g., H-2024-047) | Traceability across documents and design reviews |
| Recommendation text | Verbatim from HAZOP report | Prevents scope drift during close-out |
| Resolution required | Specific deliverable (revised drawing number, calculation reference, procedure title) | Makes close-out verification objective |
| Owner | Named individual, not a team or discipline | Accountability; can't split responsibility |
| Due date | Tied to design milestone, not calendar date | Survives schedule slips without losing urgency |
| Status + evidence | Open / In Progress / Closed + document reference | Enables audit; prevents "closed" meaning "someone said it was done" |
Linking Actions to Design Milestones
One of the most useful things you can do with an action register is tag each item with the design milestone by which it must be resolved. Not a calendar date — a milestone. 30% IFR. 60% IFD. IFC.
This does three things. First, it creates natural review gates. At each milestone, the project team knows exactly which HAZOP actions were supposed to be closed and can verify completion before issuing drawings. Second, it ensures that design changes made at 60% that affect an action resolved at 30% get caught at the next gate. Third, it gives the PSM lead a defensible position when actions are being deferred: "This was supposed to be resolved at 30% IFR. We're at 60% IFD. What changed, and who approved the deferral?"
Not all HAZOP actions carry the same risk. Before the register is handed off to detailed engineering, classify each action by consequence of non-closure:
- Class 1 — Must resolve before IFC: Actions tied to primary containment, SIS design, relief device adequacy, or process conditions outside equipment design limits. These don't get deferred.
- Class 2 — Must resolve before mechanical completion: Operational safeguards, procedure requirements, maintenance provisions. Can be resolved through commissioning phase.
- Class 3 — Must resolve before chemical introduction: Training requirements, emergency response documentation, written procedures. Part of PSSR evidence package.
Classification should be done by the HAZOP team and PSM lead together — not unilaterally by the project engineer under schedule pressure.
The Close-Out Review: What It Is and What It Isn't
Close-out of a HAZOP action item is not a statement. It's a review. The difference matters.
A statement close-out looks like this: the owner marks the action "Closed" in the register and writes "Resolution: discussed with process lead, determined existing design is adequate." No drawing number. No calculation reference. No second set of eyes.
A review close-out looks like this: the PSM lead and the action owner sit down with the register entry, the referenced resolution document, and the current P&ID revision. They verify that the HAZOP recommendation was actually implemented — not interpreted, not deemed unnecessary — and they sign off on it. The evidence gets filed against the action ID.
For Class 1 actions, the close-out review should include independent verification. The person who implemented the resolution shouldn't be the only person verifying it.
When Design Changes Reopen Closed Items
Every significant design change — any change that goes through formal MOC on a brownfield project, or through a design deviation notice on a greenfield — should trigger a HAZOP action register review. The question isn't complicated: does this change affect any system or scenario that was examined in the HAZOP?
If yes, pull the relevant action items and re-evaluate them against the revised design. Some will still be adequately resolved. Some won't. The ones that aren't get reopened — not noted as exceptions, not flagged for "consideration." Reopened.
This is uncomfortable when you're at 80% IFD and a closed action needs to be redone. It is considerably less uncomfortable than a process safety incident.
Transferring the Register to Commissioning
At mechanical completion, any HAZOP action items that are still open — or whose resolution requires operational verification — need to transfer formally to the commissioning and startup phase. This isn't automatic.
The register handoff should be a documented deliverable: a signed-off list of open items, their classification, the evidence required for close-out, and the phase (commissioning, cold commissioning, hot commissioning, initial operation) by which each must be completed.
Any Class 1 items still open at this point should be escalated immediately. There is no scenario in which an unresolved primary containment or SIS design action can be deferred past mechanical completion without explicit, documented risk acceptance from leadership.
HAZOP Support for Capital Projects
We support HAZOP preparation, facilitation, action register management, and close-out verification for capital projects across the process industries. If your project has a HAZOP register that needs structure — or is missing one entirely — we can help.
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