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There is a moment in every project when hazardous material is about to enter equipment for the first time. Before it does, someone has to be satisfied that the plant is ready: built as designed, with its protections working, its procedures written and its people trained. In process safety that check is the pre-startup safety review (PSSR).
Part 1 set out the commissioning sequence. This part explains what the PSSR covers, who should do it, and how it works on the feed section from the worked HAZOP.
Where the requirement comes from
In the United States, the OSHA process safety management standard requires a pre-startup safety review for new facilities and for modified facilities when the modification is significant enough to require a change in the process safety information. It must confirm, before highly hazardous chemicals are introduced, that:
- construction and equipment are in accordance with design specifications;
- safety, operating, maintenance and emergency procedures are in place and adequate;
- for new facilities, a process hazard analysis has been performed and its recommendations resolved or implemented before start-up, and modified facilities meet the management of change requirements; and
- training of each employee involved in operating the process has been completed.
Canada has no single federal equivalent, but the same elements appear in the CSA Z767 standard for process safety management and in provincial requirements for regulated facilities. Whatever the jurisdiction, the four questions above are good practice for any plant handling hazardous materials, and for small plants that are not regulated as major hazard sites.
What the review covers
| Area | Questions the review asks | Evidence |
|---|---|---|
| Built as designed | Does the plant match the latest P&IDs? Are materials, ratings and supports as specified? | Walkdown with marked-up P&IDs; mechanical completion certificates |
| Integrity | Have pressure tests and leak tests passed? Are temporary blinds and strainers recorded? | Test records; blind list |
| Relief and protection | Are relief valves installed, set and certified, with block valves car-sealed open? Have all safety functions been tested? | Relief valve certificates; safety function test records |
| Hazard study actions | Is every HAZOP action closed, or accepted as not needed before start-up with a reason? | Action register with sign-offs |
| Changes | Has every change since the HAZOP been through management of change? | MOC records |
| Procedures | Are operating, start-up, shutdown, emergency and maintenance procedures written, reviewed and available? | Approved procedures in the control room |
| People | Are operators trained on the procedures? Is the start-up team staffed for every shift? | Training records; start-up roster |
| Emergency response | Are fire protection, gas detection, safety showers and emergency plans in place and tested? | Test records; drill record |
Worked example: the feed section
The HAZOP of feed heater E-101 produced seven actions. Before feed enters E-101, the review checks each one. The status below is an illustration of what a review might find.
| No. | HAZOP action | Status at review | Before start-up? |
|---|---|---|---|
| 1 | Independent outlet temperature trip: TT-103 and TSHH-103 close new steam shutoff valve XV-103 at 95 °C | Installed; tested end to end from TT-103 to XV-103 | Required; closed |
| 2 | High and low temperature alarms on TIC-101; low alarm at 70 °C stops reactant addition | Configured; alarms and the addition stop tested | Required; closed |
| 3 | Confirm shell design pressure is at least the maximum steam header pressure, or the header has its own relief | Nameplate and header regulator settings checked | Required; closed |
| 4 | Decide how a tube leak will be detected before condensate returns to the boiler | Study under way; interim daily conductivity check of the condensate | Deferred with interim measure, owner and date |
| 5 | Confirm PSV-102 is sized for blocked-in heating and define its discharge | Calculation checked; discharge routed to the closed drain; certificate on file | Required; closed |
| 6 | Check valve on line DN50-P-1004 against reverse flow from R-101 | Installed and inspected | Required; closed |
| 7 | High flow alarm or trip that keeps the reactant addition to three hours or longer | High flow alarm installed; trip still in design with the reactor node | Required; open |
One required action is open. Action 7 protects against adding reactant faster than the reactor jacket can remove the heat, the scenario in the runaway reaction post. The review cannot say "go" for the reactor until it closes, or until the team agrees and documents an equivalent safeguard. The feed section can still be commissioned on solvent in the meantime. Action 4 can be deferred because a daily check of the condensate covers the risk until the study is done, provided the deferral is recorded with a date and an owner.
Who should do it
A PSSR is not a sign-off by the project manager. A small team with independence from the people who built the plant works best: an operations lead who will run the plant, a process engineer, a maintenance or mechanical integrity representative, and someone from health and safety. For a modification, a review sized to the change is enough; the management of change process should say when a PSSR is required and how large.
Go, go with conditions, or no-go
The review ends with a decision. Go: all required items closed. Go with conditions: items that do not affect safe start-up are listed with owners and dates, and the conditions under which the plant may run until they close (for example, a reduced rate). No-go: a required item is open. The decision and its conditions are written down and signed by the person accountable for the plant.
Key points
- A PSSR confirms, before hazardous materials go in, that the plant is built as designed, procedures are ready, hazard study actions are dealt with and people are trained.
- Every HAZOP action is either closed or formally deferred with a reason, an owner and a date.
- Relief devices and safety functions are verified, not assumed.
- Use an independent team, and record a clear go, go-with-conditions or no-go decision.
Next: Part 3, start-up and the performance test.
The plant, schedule and numbers in this series are an illustrative example. Commissioning and start-up must follow your own procedures, the vendors' instructions and the regulations that apply where you operate.
