: Equipment connected together by piping of adequate capacity, free from potential blockages, and without isolating valves, can be considered a safety system for the purpose of pressure relief.
Maintain sizing sheets, material certificates, and installation diagrams for every safety device on-site. Iso 4126-9 Pdf
. It serves as a critical guide for ensuring that relief systems function as a cohesive "safety system" to prevent pressure from exceeding maximum allowable limits. ISO - International Organization for Standardization Scope and Applicability : Equipment connected together by piping of adequate
Mandates a realistic risk analysis to determine the necessary discharge capacity and the most appropriate safety concept for the specific vessel or system. It serves as a critical guide for ensuring
The standard explicitly excludes stand-alone bursting disc safety devices from its scope, which are covered separately under . This distinction is important because bursting discs in isolation have different application and installation considerations compared to the devices covered in Part 9.
If your facility operates under PED (EU Pressure Equipment Directive) or has a global supply chain, ISO 4126-9 is mandatory. If you operate only in the US, you may still use it as a best-practice reference.