MEC/Process/TBT-MEC-023

Commissioning Maintenance and Operation

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Presenter		Project
Location		Date

Commissioning is the process of testing and proving installed equipment works correctly before handover to the client.
During commissioning, construction and operational activities happen simultaneously, creating unique interface risks.
Equipment being commissioned may start, stop, or move unexpectedly as tests are carried out by the M&E team.
CDM 2015 requires coordination between construction workers and operational teams during this transition phase.
PUWER 1998 applies to all equipment under test — guards, isolations, and safety systems must be in place.
Live process fluids including sewage, chemicals, and pressurised water may be introduced during commissioning.
Operational areas may require permits, LOTO procedures, and confined space entry during concurrent construction.
Construction workers must understand which areas are under commissioning control and follow restricted access rules.
Maintenance activities on operational plant also require coordination with the client's operations team at all times.
The boundary between construction responsibility and operational control must be clearly defined and communicated.

Unexpected start-up	Equipment under commissioning test can energise or rotate without warning — workers near the machine face crush and entanglement risk.
Live process hazards	Introducing sewage, chemicals, or pressurised systems during testing creates exposure risks not present during construction.
Interface management	The overlap between construction and operations is the highest-risk phase — clear boundaries prevent confusion and accidents.

Don't

Attend the commissioning interface briefing before working near any area under test.
Check the daily commissioning schedule to know which equipment is being tested today.
Confirm isolations are in place and locked off before working on or near process equipment.
Follow the permit to work system for all activities in commissioned or operational areas.
Report to the commissioning manager before entering any area marked as under test.
Maintain communication with the M&E commissioning team throughout your work activity.
Respect all barriers, signs, and exclusion zones around equipment under commissioning.
Ensure guards are refitted after any maintenance work before equipment is returned to service.
Coordinate your task timing to avoid clashing with planned commissioning test sequences.
Clear all tools, materials, and debris from equipment before it is returned for testing.

DON'T enter a commissioning area without permission from the commissioning manager.
DON'T assume equipment is isolated because it was off yesterday — check the status today.
DON'T remove or bypass any isolation, lock, or tag placed by the commissioning team.
DON'T leave tools, bolts, or materials inside equipment or pipework under commissioning.
DON'T open valves, operate switches, or start equipment without specific authorisation.
DON'T work alone in areas where live process fluids are being introduced for testing.
DON'T continue construction activities if they conflict with a live commissioning test.
DON'T ignore alarms or warnings during commissioning — they may indicate a genuine fault.
DON'T treat commissioning areas as standard construction zones — different rules apply.
DON'T hand back equipment for testing until all snag items and safety checks are complete.

See also: Commissioning Safety | Lock Out Tag Out Awareness

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