Risk Analysis and Risk Management for Offshore Platforms: Lessons From the Piper Alpha Accident

A probabilistic risk analysis (PRA) framework is used to identify the accident sequence of the 1988 Piper Alpha accident. This framework is extended to include the human decisions and actions that have influenced the occurrences of these basic events, and their organizational roots. The results of this preliminary analysis allow identification of a wide spectrum of possible risk reduction measures, ranging from classical technical solutions such as addition of redundancies, to organizational improvements such as a change in the maintenance procedures. An explicit PRA model is then developed to assess the benefits of some of these safety measures based, first, on the original contribution to the overall risk of the failure modes that these measures are designed to avert, and second, on the degree to which they can reduce the probabilities of these failure modes. PRA can then be used as a management tool, allowing optimization of risk management strategies based both on the qualitative information about causalities provided by the accident, and on the quantitative information about failure probabilities updated in the light of new events. It is shown how PRA can be used to assess, for example, the cost-effectiveness of safety measures designed to decrease the probability of severe fire damage onboard platforms similar to Piper Alpha.