EN 12266 vs API 598 — Shell and Seat Test Standards
API 598 and EN 12266 both cover production pressure testing of industrial valves. Projects usually name one. Write the exact standard and leakage rate on the RFQ.
Quick selection
US / ASME packages often cite API 598. EN BOQs cite EN 12266-1. Related: API 598 vs API 6D.
Comparison table
| Factor | API 598 | EN 12266 |
|---|---|---|
| Common use | ASME Class valves, US specs | EN / PN valves, EU specs |
| Covers | Shell and seat / closure tests | Shell and seat tests with rate classes |
| Leakage language | Allowable rates by size/type | Rate A (zero visible) … other rates |
| Docs | API 598 test report | EN 12266 test report / rate stated |
| Buyer action | “Tested to API 598” | “EN 12266-1 Rate __” |
Not a design standard
Testing does not replace design standards (API 600, B16.34, EN product standards).
- Soft-seat vs metal-seat leakage expectations differ.
- Cryogenic / FE / fire tests are additional.
RFQ wording that works
- “Each valve shell and seat tested to API 598; report with MTC 3.1.”
- “Testing per EN 12266-1 Rate A; certificate required.”
FAQ
Is Rate A zero leakage forever?
Rate A means no visually detectable leakage during the test — not a lifetime guarantee.
Can one certificate cover both standards?
Only if the procedure satisfies both and the project accepts it.
API 6D testing vs 598?
API 6D has its own test requirements for pipeline valves.
Pneumatic vs hydrostatic?
Follow the named procedure and safety rules.
Related RFQs and hubs
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