Traditionally, consideration of plant reliability has been largely a technical exercise involving comprehensive engineering and metallurgical investigations and component life assessments. Clearly the cost and time involved in this type of exercise is significant. However using a risk based approach CIS can quickly identify and prioritise the most critical components in terms of their impact of specific performance indices e.g. reliability. This type of approach is largely based on a “top down” engineering risk based evaluation of plant condition, operation and historical maintenance. Where possible a comparison is made with available international experience of components of similar design and service. Economic considerations, in terms of the market environment versus historical and projected performance of the unit, can be used to provide a preliminary estimate of probable income. A high level cost benefit evaluation of replacement or repair of the critical components that yield the highest impact on the selected performance indices can then be carried out.