ISO 5208 Check Valves
What ISO 5208 requires for check valves — applicability, key and testing requirements, the alternative standards, and compliant supply with full certification.
What does ISO 5208 require for check valves?
ISO 5208 (Industrial Valves - Pressure Testing of Metallic Valves, International Organization for Standardization (ISO)) sets the design, material and testing requirements for check valves in its scope. ISO 5208 is the international standard for pressure testing of metallic valves. It defines test procedures, pressures, durations, and permissible leakage rates for shell (body) tests and seat leakage tests. ISO 5208 is commonly specified alongside API 598 for export and international projects where ISO rather than API standards are preferred. The two standards are largely equivalent but differ in leakage rate definitions and acceptance criteria labelling.
Applicable Pressure Classes
Key Requirements
- Shell test pressure: 1.5× maximum allowable pressure at 38°C (100°F)
- Shell test duration: minimum 15 seconds for DN ≤ 50; 60 seconds for DN > 50 to DN 300; 120 seconds for DN > 300
- Seat test pressure: 1.1× maximum allowable pressure OR 6 bar minimum
- Leakage Rate A (zero leakage): no measurable leakage - required for gas and toxic fluids
- Leakage Rate D: standard for most industrial valves
- Pneumatic test alternative: 6 bar (87 psi) for gas valves where liquid test not practical
- Test medium: water (with corrosion inhibitor) for shell test; water or air/nitrogen for seat test
Testing Requirements
- Shell test: 1.5× rated pressure, per duration table
- Seat test: 1.1× rated pressure, per leakage rate
- Pneumatic test option: 6 bar air or nitrogen for gas valves
Alternative Standards for Check Valves
Other standards that also govern check valves — useful for spec cross-acceptance.
Related Standards
Connected Engineering
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