Pre-commissioning and system turnover

How does Pre-commissioning and system turnover work, step by step?

1. 1

   Step 1: Divide the plant into systems and fix the boundaries

   The plant is broken down into systems that can be completed, isolated, tested and operated independently. Boundaries are drawn deliberately, usually at valves, at isolations or at defined interfaces, and they are marked on drawings that everybody works to. This is done early, because construction has to be planned and progressed against those systems rather than against areas. An ambiguous boundary is discovered at the worst moment, when the commissioning team needs to isolate something and finds it cannot be separated.

2. 2

   Step 2: Agree what a turnover package contains

   The commissioning team, the operator and the contractor agree the content of a turnover package before the first one is produced: the inspection records, test certificates, weld and material records, calibration certificates, as-built drawings, punch list status and cleanliness confirmations that a system needs before it will be accepted. Agreeing this at the start avoids the most common failure on power projects, which is a system that is physically complete but cannot be accepted because the paperwork was never collected.

3. 3

   Step 3: Build the documentation as the work proceeds

   Records are compiled as the work is done, not reconstructed afterwards. Every inspection, test, calibration and weld is recorded against its system at the time. Most sites run a completions database or register so that the status of every system is visible and the outstanding items are known. This discipline is what allows the first turnover to happen early, and it is the single strongest predictor of whether a project will commission on programme.

4. 4

   Step 4: Complete the physical checks system by system

   For each system the team confirms that installation is complete and matches the design, that supports, hangers and spring settings are correct and released where required, that valves and instruments are the right ones in the right places and correctly oriented, that insulation and protection are complete, that labelling is in place, and that electrical connections and earthing are proved. These are unglamorous checks and there are thousands of them, which is why they are done progressively rather than in a final push.

5. 5

   Step 5: Clean, flush and prove the system is clean

   Systems are cleaned and flushed so that construction debris does not reach the machinery. For most systems this is flushing, blowing through and internal inspection, all recorded formally before the system is closed. For the main steam pressure parts, cleaning is a different matter entirely: internal chemical cleaning and steam blowing are specialist operations carried out by the plant supplier and the commissioning team under the operator's permit-to-work system, with the area cleared and all other work stopped. They are planned as major events in the programme.

6. 6

   Step 6: Walk down the system jointly and agree the punch list

   The contractor, the commissioning team and the operator walk the system down together against the design and record every outstanding item on a punch list, categorised by whether it prevents turnover, prevents operation or can be completed later. Joint walkdown is what makes the categorisation stick, because all three parties have seen the same thing. Items that prevent turnover are cleared before the package is submitted rather than argued about afterwards.

7. 7

   Step 7: Turn the system over and change the control regime

   When the package is accepted the system passes to the commissioning team and the rules change. From that moment the system is under the operator's permit-to-work system, and any work on it - including remaining punch list items - is done only under a permit issued by the operator. Isolation, tagging and access control become the operator's responsibility. Boundaries between turned-over systems and live construction areas are marked physically on site, not just on drawings.

8. 8

   Step 8: Manage two organisations working side by side

   For a long period the site runs two regimes at once, and the interface between them is a genuine safety risk. Most projects manage it with joint planning meetings, clear physical demarcation, shared briefing of both workforces, and a single co-ordinating authority for the interface. Everyone on site is briefed on what the boundaries mean and what to do at them. The habit that matters most is simple: nobody crosses into a turned-over system to do anything, however small, without a permit.