ISO 5208 - Industrial Valve Pressure Testing
ISO 5208 is the international standard specifying pressure tests for industrial valves: shell (body) tests, seat leakage tests and operational verification. It defines leakage rate acceptance criteria by leakage grade, which makes it stricter and more precise than many older national test codes.
Leakage grades
| Grade | Typical use |
|---|---|
| Grade A | General industrial service, no visible drip |
| Grade B | Very low leakage, bubbles counted in gas tests |
| Grade C | Low leakage, drops counted per diameter |
| Grade D | Near zero leakage for critical isolation |
Relation to API 598
ISO 5208 is broadly aligned with API 598 but expressed in SI units and with explicit counting-based acceptance rates. Many pipeline valves are tested to API 598 or ISO 5208 rate A/B depending on buyer specification; soft-seated valves typically meet Grade A or B easily, while metal-seated designs may be specified with higher grades only where the application justifies the cost.
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