Geoff Covey, Dennis Shore, Reg Harvey and Gerke Faber
Many projects go well until they enter the commissioning phase and then even comparatively minor problems can cause a disproportionate amount of trouble and delay.
The commissioning stage of the project is the time when delay is most expensive because the plant is paid for but is not yet producing an income. It is also the time when there is the most attention on the project and impatience from above can cause rash decisions to be made in an attempt to minimise the delay.
If the commissioning experience is analysed after the event (which rarely happens) the reasons for the difficulties can usually be traced back to inadequate preparation for commissioning.
This paper will cite various real-life problems that the authors have encountered and show how these might have been avoided, or at least reduced in severity by proper preparation. In every case, it is not simply a matter of ‘being wise after the event’. With proper planning measures could have been in place to address the problem when it arose.
The case studies will also include some for which proper planning in advance did result in avoidance of delays. These cases are often harder to identify because the problems that did not arise or which were solved promptly are simply not noticed or not documented by anyone. This can create difficulties in the next project because the measures which solved problems that did not cause much disruption can readily be omitted.
Successful commissioning of new or substantially modified plant does not happen automatically. It requires appropriate design and preparation. The sorts of measures required for successful commissioning will generally also be useful for routine start-ups of the plant in the future, so there are also long-term benefits in proper preparation for commissioning.
When considering the costs of poor commissioning, most emphasis is usually on lost production time. Although this is important, and easy to quantify, it is generally relatively unimportant compared with the costs associated with damage to equipment and on-going inefficient operation.
Attempts to accelerate commissioning of a plant that was not properly designed with adequate provisions for commissioning can cause considerable damage due to hydraulic hammer, improper warm up resulting in shortened material life of refractories etc. and failure to run in or bed in rotary equipment. Even a fairly well managed commissioning period can be the equivalent of several years of normal operation in terms of equipment life. This often leads to compounding of losses, because the damage caused by attempting to avoid production loss early on results in the need for a premature shut (often one which is unplanned) to repair it. Consequently overall the production loss is greater than if more time had been taken over the initial commissioning.