5th CCPS China Conference on Process Safety, Nanjing, China
Changes are inevitable in any processing facilities during both design and operational phases. Proper management of these changes is of utmost importance in order to address the associated risk. Identifying the changes that need careful attention becomes the key for the management of change process. A number of incident investigation reports identified that ineffective management of changes (MOCs) is the major contributing factor for the incidents. Consequently, the industry has developed elaborate MOC processes. Nevertheless, in the author’s experience, it is still not uncommon to find that the MOC team failed to identify changes that need to be subjected to MOC process or failed to identify all hazards associated with the change under review. This can be attributed to the lack of knowledge of the original basis of design, or insufficient experience. One of the other factors could be that some MOCs introduced new hazards which were not relevant to the original design, and thus were not envisaged.
Through a series of case studies taken from the operating plants, this paper illustrates how following typical MOC procedures/checklists may not be adequate on its own to meet the objectives of such process and significant hazards may remain unidentified. Even seemingly simple changes such as minor modification of operating conditions, replacement of a transmitter with the same specification from an alternate manufacturer or installation of a new safety systems etc., deserve a thorough evaluation. Thus, often an “outside the box” approach may be necessary to bridge this gap. The paper also aims to provide guidance for improving the MOC review process during the operational phase.