Pressure Relief Valve Inspection Interval

摘要

Determining the correct interval for pressure relief valve inspection, testing, and maintenance remains a major challenge for facilities covered by the U.S. Occupational Safety and Health Administration Process Safety Management Standard. To this end, guidance is provided by API Standard 510, Pressure Vessel Inspection Code: In-Service Inspection, Rating, Repair, and Alteration, by API Recommended Practice 576, Inspection of Pressure-relieving Devices, by API Standard 520, Sizing, Selection, and Installation of Pressure-Relieving Devices, Part II-Installation, and by NB-23, National Board Inspection Code-Part 2 Inspection. Furthermore, ASME BPVC, Sections I and VIII, provide general guidelines for the repair of pressure relief valves. However, the testing and inspection interval listed, up to ten years, is the maximum time span between shop inspections and overhaul. Further direction is often requested for determining the proper interval for valves in typical process services, especially in cases of PRV chattering. Recent API STD 520 Part II guidance on performing engineering analyses for PRV installations, based on service and specific installation, is included here. In this paper, a decision-making approach to determining these intervals based on a combined understanding of risk-based inspection, quality assurance, engineering analyses, and facility experience is presented. The approach provides process operators and managers with additional assistance in making this determination.