Restarting a Plant After a Shutdown: A Process Safety Checklist

A shutdown ends when the work is complete. A safe restart begins only when the plant, its safeguards and its people are ready to contain a loss of control.
This distinction matters after annual maintenance, a turnaround, a power interruption or a major modification. Work may be mechanically complete while a relief path remains blocked, a trip has not been tested, an operating procedure is obsolete or an isolation has not been transferred correctly. A pre-startup safety review gives the operating team a structured go or no-go decision before hazardous energy or material enters the system.

Start with the approved scope

Compare the installed plant with the approved work pack, drawings and management-of-change record. Confirm every temporary change, bypass, blind, temporary hose and vendor modification. A replacement is not automatically replacement-in-kind because it fits the same footprint. Duty, metallurgy, isolation performance, control logic and inspection requirements can all change the risk.
Give one accountable person the current action list. Separate actions that must close before startup from controlled follow-up actions. A deferred task needs a risk basis, owner, completion date and operating restriction. "We will fix it next week" is not a control.

Verify the safeguards in the field

Paper completion cannot prove a plant is ready. Use a multidisciplinary walkdown to verify the physical line-up and test records for safeguards that prevent or limit a major incident:

• relief devices, vents and discharge paths;
• alarms, trips, interlocks, shutdown valves and detectors;
• firewater, foam, deluge, emergency power and communications;
• isolation boundaries, drain and vent positions, and removal of temporary equipment; and
• access, escape routes, lighting, signage and control-room indications.
  If the shutdown changed throughput, inventory, chemistry, equipment arrangement or operating limits, ask whether the earlier HAZOP, LOPA, consequence model or MHI assessment still represents the plant. The answer may be a focused review, not always a full study, but it must be documented by competent people.

Prepare the operating team for the first hours

The first startup sequence often has the highest uncertainty. Operators need approved normal, startup, abnormal and emergency procedures that match the installed plant. Discuss the expected sequence, hold points, escalation triggers, emergency shutdown conditions and handover arrangement before the first valve moves.
Confirm staffing and specialist support for the first shift. Avoid combining commissioning, contractor work, performance testing and routine production unless simultaneous-operation risks have been reviewed. The MHI compliance discussions held by industry in July 2026 reinforce the value of evidence that shows how a control works in practice, not only that a procedure exists.

Record an explicit go or no-go decision

End the review with an accountable manager’s decision and a retained record of the evidence considered. If the answer is no-go, define what must change, who owns it and when the decision will be revisited. That protects the team from commercial pressure and creates a traceable basis for the restart.
📥 Download the Plant Restart and PSSR Readiness Checklist (PDF)
MMRisk supports HAZOP follow-up, management of change, PSSR and startup-readiness reviews for high-hazard facilities. Talk to our process safety team before the next restart.

FAQ

Is a PSSR required after every shutdown?
Use a PSSR before hazardous material or energy is introduced into new, modified, repaired or restarted equipment where the shutdown work could affect process safety. The review scope should match the risk and change.
Can actions remain open at startup?
Only if the remaining action does not compromise startup safety and a documented interim control, owner and due date are in place. Actions that affect containment, safeguarding, procedures or competent staffing should close first.