Onshore vs offshore commissioning: what actually differs

Both onshore and offshore commissioning follow the same IEC standards and the same logical sequence: visual, insulation resistance, continuity, functional, energisation, performance. The differences are operational, not technical — but those operational differences swing the schedule, the budget, and the risk profile of the entire job.

What changes offshore

• POB (persons on board) limits cap how many engineers can mobilise
• Helicopter weather windows control mobilisation and demobilisation
• Hazardous-area certification (ATEX/IECEx) gates every instrument used
• Permit-to-work systems govern every lift, isolation and entry
• Spare parts must be on-board before sail-away — no next-day delivery

Planning the test pack differently

Onshore, you can re-run a test if the result looks wrong. Offshore, every re-run costs platform time. We compress the test sequence so each piece of equipment is touched once, with all required readings captured in a single visit. The method statement that ships with the team is more detailed and far more sequenced than the equivalent onshore document.

Documentation discipline

Test records have to be approved before the team leaves the platform. That sounds obvious until you've watched a result wait three weeks for a signature because the witness was on rotation. We use field-tablet workflows that capture witness signatures at the point of test, so the as-tested pack is closed before the helicopter lands back on shore.