Research and Application of Risk Assessment Methodology for Power Station Boiler Superheaters

Risk-based inspection (RBI) has been applied to good effect in relation to pieces of equipment and pipelines in the petrochemical industry worldwide, but to the best of our knowledge application of RBI to power station boilers has not hitherto been reported. The tubes of the four key components, namely, the economizer, the water-cooling wall, the superheater, and the reheater, are prone to blast due to direct fire heating. Such a blast always causes unplanned shutdown and has severe safety implications. Based on the “API 581-2000” code (Risk-Based Inspection Base Resource), the failure mechanisms of power station boilers have been studied, and the high-temperature smoke erosion factor and high-temperature creep factor have been calculated. Then, considering specific situations in China, such as material quality and extended service, a failure modification factor based on remaining life has been proposed. Finally, two risk assessment projects have been carried out; after delineating the risk levels of the tubes, appropriate management suggestions have been proposed. The obtained data should provide some technical support for the application of RBI to power station boilers.