Plant Recommissioning / Restart SWMS

Plant recommissioning and restart covers the controlled reintroduction of energy and process flows into fixed and mobile plant following maintenance, shutdown, modification or breakdown. The work spans permit-to-work close-out, lockout/tagout (LOTO) removal, function checks, dry runs without product, and progressive wet runs with live media — across electrical, mechanical, hydraulic, pneumatic, thermal and stored-energy systems. Under WHS Regulation 2011 r291 and the harmonised 2025 amendments, restart of plant where multiple energy sources are reintroduced or where stored energy may be released is classified as High Risk Construction Work (HRCW), making a written Safe Work Method Statement mandatory before work commences. The risk profile is dominated by latent energy, mistimed isolations, and incomplete handovers between maintenance and operations crews. A documented SWMS aligns the recommissioning sequence with AS/NZS 4836, AS/NZS 3000 and the Managing Risks of Plant in the Workplace Code of Practice, ensuring every isolation point, witness check and sign-on is verified before energisation.

Hazards identified

7 hazards covered, sorted by priority.

Control measures

Hierarchy-of-controls order: elimination → substitution → isolation → engineering → administrative → PPE.

1. 1Elimination — Where reasonably practicable, complete all maintenance tasks before any restart sequence so no personnel remain within the plant envelope when energy is reintroduced.
2. 2Elimination — Remove redundant temporary test leads, jumpers and bypass straps from control circuits before LOTO removal so latent defeats cannot energise on restart.
3. 3Substitution — Replace manual valve cracking for pressurisation with motor-operated valve ramping controlled from the DCS, eliminating worker presence at the pressure boundary during wet run.
4. 4Engineering — Apply staged energisation through interlocked field isolators, soft-starters and pressure ramp profiles per AS/NZS 3000 cl 2.3 verification, with witness of zero-energy state before each step.
5. 5Engineering — Install fixed machine guarding, vibration trip protection and emergency stop functional test prior to first rotation, verified against AS 4024.1 functional safety requirements.
6. 6Administrative — Execute restart under a formal Permit-to-Work close-out checklist with signed isolation register reconciliation, witnessed LOTO removal and documented sequence sign-off per Managing Risks of Plant CoP.
7. 7Administrative — Conduct pre-start SWMS briefing with all restart crew, control room and field operators, recording attendance, hazard walk and stop-work authority on the SWMS sign-on register.
8. 8Administrative — Establish exclusion zones with hard barriers and signage during dry and wet runs; only the nominated restart crew permitted inside the zone per r291 HRCW controls.
9. 9PPE — Issue arc-rated clothing to category 2 minimum, insulated gloves tested per AS/NZS 2225, safety glasses, hearing protection class 5 and steel-capped boots for all field restart activities.
10. 10PPE — Provide chemical splash suits, full face shields and respiratory protection rated to AS/NZS 1716 where wet-run media includes hydrocarbons, acids, caustics or hot condensate above 60°C.

Applicable Codes of Practice

High-Risk Construction Work triggered

Worked example

On a regional water treatment upgrade, the commissioning supervisor convenes a pre-start brief at 0630 in the site office before recommissioning a 315 kW raw-water pump set following bearing replacement and VSD firmware update. The Plant Recommissioning / Restart SWMS is projected on the screen and walked through line by line with the electrical fitter, mechanical fitter, control room operator and the appointed isolation officer. Working through the hazard register, the crew flag that the discharge non-return valve was disassembled during shutdown — a stored-energy and back-flow risk not present in the standard sequence. The team selects the engineering control of staged DCS-ramped pressurisation and adds an exclusion zone extending two metres beyond the flange, marking it on the site plan attached to the SWMS. Each worker signs the sign-on register acknowledging stop-work authority. During the dry run at 0915, the fitter observes coupling vibration exceeding the trip setpoint flagged in the SWMS control measure for AS 4024.1 functional testing. He invokes stop-work, the supervisor re-isolates per the LOTO removal reversal procedure documented in the SWMS, and the alignment is re-shimmed. The SWMS is amended in the field, re-signed by all parties, and the wet run proceeds only after the amended document is re-briefed — demonstrating the SWMS functioning as a live control document rather than a filed record.

Related legislation

• WHS Act 2011 (model)
• WHS Regulation 2025
• Construction Work CoP

Frequently asked questions