Commissioning after major rebuilds and new constructions

Geoff Covey, Dennis Shore, Reg Harvey and Gerke Faber

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Commissioning is often the most difficult part of a capital project because although it is almost always possible to construct a plant, until it is complete there will always be some uncertainties about how a one off system will behave.

Unfortunately, planning for commissioning is rarely as thorough as for other stages of the project and there is always pressure to get the finished plant on line as soon as possible.

Further, in many organisations there are a limited number of people with experience of commissioning, because large projects are infrequent.

Together these factors often lead to inefficient and even damaging strategies being applied.

This paper discusses strategies and the development of skills that will usually result in more effective commissioning.


Many capital projects, both for new plants and for substantial rebuilds, proceed quite well until attempts are made to go on line. At this point there are often prolonged difficulties in achieving design performance or even in getting sections of the plant to work at all.

Our experience from many projects is that this occurs for two related reasons.

Firstly, commissioning a new plant is inherently the most uncertain part of the project. Construction may have its difficulties, but there is little danger that the plant cannot be put together as designed. Projects such as the Sydney Opera House, in which the technology for forming the sail elements had not been resolved when construction commenced, are rare. However, the finished plant will almost always be unique in some ways – often in many ways , and there is no certainty that every possible adverse interaction has been identified, let alone planned for (experience shows that it is very rare for every possibility to be covered).commissioning_after_major_rebuilds_figure-01

Secondly, although great care is taken in preparing design, procurement and construction schedules, often little thought is given to planning of commissioning. On even the most elaborate project schedules, commissioning is usually represented by a single bar. Worse, delays in construction are frequently ‘overcome’ by ‘we will reduce the commissioning time’. The project schedule chart below illustrates that even a simple project deserves a well planned and clearly defined commissioning schedule. A prolonged or difficult commissioning can severely reduce the net present value of a project and result in considerable deterioration of the equipment. Therefore it pays to be well prepared for starting up the plant.

Generally there is a minimum time for any start up. Efforts to reduce this time will be less cost effective than ensuring that resources are available to address unanticipated upsets.

This paper will attempt to describe some of the measures that can be taken to improve the commissioning/start up procedure.