Validating a Risk-Based Inspection Tool The Evolution of the API RBI Protocol

摘要

Over the past few years, a group of companies working under the American Petroleum Institute have developed a risk-based inspection protocol. The original form of this protocol addressed pressure vessels and piping, and common failure mechanisms applicable to each, for chemicals common to the refining industry. Since then, the protocol has been expanded to address more failure mechanisms, new equipment items such as fired heaters, shell and tube heat exchangers, atmospheric storage tanks, and pressure relief valves, and additional chemicals. Throughout, the tool has been a relative risk-ranking method, incorporating relative measures of failure likelihood and failure consequence. In the past year, the tool has been validated and calibrated in absolute terms. This allows not only optimal allocation of a fixed number of resources, but defines the optimal level of resources in terms of actual dollars per year. This, in turn, allows rigorous cost-benefit analysis of inspection options. The API RBI protocol and the methods for validating it are presented. The implications of these findings on commonly held assumptions for equipment failure frequencies and consequence analyses used in quantitative risk assessments are also discussed.