Safety devices for protection against excessive pressure - Part 4: Pilot-operated safety valves (ISO 4126-4:2013)

This technical specification addresses the design, testing, and performance criteria for pilot-operated safety relief valves intended to prevent overpressure in pressure vessels and systems. It outlines the fundamental requirements for ensuring that these critical safety devices function reliably under specified operating conditions. The document details the methods for determining set pressure, lift characteristics, discharge capacity, and leakage rates. It further specifies the construction requirements for valve components, including materials compatibility and sealing mechanisms. Procedures for type testing and initial verification are provided to confirm compliance with the established safety standards. This document aligns with international practices to ensure interoperability and safety across diverse industrial applications. It serves as a comprehensive guide for manufacturers, testing laboratories, and regulatory bodies involved in the certification and implementation of these safety components. The guidance covers various operating fluids and pressures, ensuring that the devices operate effectively to protect equipment and personnel. Adherence to these technical provisions helps maintain system integrity and prevents catastrophic failures due to excessive internal pressure buildup.