Experience With the Application of Risk Concepts in Developing Equipment Prioritization Systems

As consultants to refining and petrochemical companies, Det Norske Veritas (DNV) has been involved in developing risk based prioritization and management systems for a number of years. This paper follows DNV’s experience as it developed these methods, beginning with the initial concepts through the completion of several projects. The paper discusses some of the efforts that have been made to standardize the application of risk based prioritization. In applying risk based inspection, the likelihood and consequence of each individual item is considered and the result is a ranking system that identifies and ranks failures on a uniform scale. In virtually every study DNV has performed, the “Pareto Principle” has been confirmed: at least 80% of a plant’s total risk exposure is due to at most 20% of the equipment. In many plants, the 90% of the risk is due to only 10% of the equipment. The principle is demonstrated here by presenting the overall distributions of risk that have resulted from prioritization studies that DNV has done. The highest expected return is produced by prioritizing maintenance and inspection efforts to concentrates on this subset of items.