Abstract

Safety valves are important devices to protect system by relieving pressure in oil refining and chemical equipment. According to API 576-2017 and API 510, the inspection interval for safety valves should not be more than 10 years. Also, TSG ZF001–2006 in China specifies the inspection interval for safety valves is only 1 year. However, the maintenance interval for petrochemical units normally is 3∼5 years, which thus results in the inconsistency between its inspection interval and the maintenance interval. This study firstly conducts contrastive analysis about the difference of major regulations and standards for safety valves inspection between China and API standards, and then performs thorough investigation of the operational management and regulation about the extension for safety valves inspection interval in the typical Chinese petrochemical enterprises. Besides, the failure modes and risk level of safety valves are investigated by quantitative analysis of 44,692 safety valves engineering application data in oil refining and chemical plants based on Risk-Based Inspection (RBI) technology. The result indicates that the overall risk level of safety valves is low, as the percentage of safety valves with a high-risk level is less than 1%, and the accident rate caused by safety valves failure is less than 0.005%. In addition, this study analyzes the limitations of specification such as TSG ZF001–2006 in terms of safety valves inspection and the application of regulation extension. Based on above analysis, the specifications and standards about safety valves should be revised and introduce the RBI technology to extend the inspection interval.

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