the point Eric mentioned about how the equipment stored I agreed it is overlooked especial when the equipment is kept and exposed on sign and rain

In addition there is an area that is often overlooked in major capital projects as well as mega projects… This is related to equipment storage & preservation from time of departure from the vendor to the time of energization…
In my experience no matter how good the commissioning planning is if the equipment was not properly stored & proper vendor preservation implemented or industry best practice preservation implemented then commissioning delays are incurred…

Additional Concerns for Procurement that indirectly related to Commissioning:
Clear requirements for spares parts outlined in the purchase orders:
commissioning spares / 2 year operational spares / 5 year operational spares

First Fill Grease & Lubricants or equivalents (frequency of change for operational preventive maintenance cycle & planning)…

The additional items of spares & lubricants may not directly impact commissioning & the commissioning schedule; but can impact when equipment could be available for commissioning if some items utilized in pre-commissioning activities are long lead items…

I have often heard about commissioning being the final phase of a project – however, from all that I have learnt from Paul and the CSU team – I am now much better informed as to when commissioning should really commence.