Every industrial valve ships with a factory test report — but the acceptance criteria behind that report depend on which test standard your project references. The two you will meet most often are API 598 (North American practice) and EN 12266 (European practice, with ISO 5208 behind it). They do not accept the same leakage.
What Both Standards Cover
Both define the shell test (body integrity at 1.5× rated pressure) and the seat closure test (leakage across the closed valve, typically at 1.1× rating). The differences live in test durations, allowable leakage rates, and how they are expressed.
API 598 in Practice
- Referenced by API 600, 602, 623 and most ASME-world purchase specs.
- Resilient-seated valves: zero visible leakage during seat test.
- Metal-seated valves: allowable drop/bubble counts scale with valve size (e.g., a defined number of drops per minute per NPS).
- Test durations are short and size-dependent — from 15 seconds on small bore up to a few minutes on large valves.
EN 12266 in Practice
- Referenced on PED / EN 13480 piping projects and most European datasheets.
- Uses leakage Rates A through G (from ISO 5208): Rate A = no visible leakage; each step up multiplies the allowable rate.
- The spec sheet states the rate explicitly, e.g. “seat test per EN 12266-1, Rate A”.
How to Compare Them on a Datasheet
| Requirement | API world | EN world |
|---|---|---|
| Soft-seated ball valve | API 598 — zero leakage | EN 12266-1 Rate A |
| Metal-seated gate valve | API 598 drops/bubbles by size | Rate C–D typical |
| Shell test | 1.5× CWP | 1.5× PS |
When a Canadian or Turkish EPC orders from a European mill — or vice versa — the mismatch between “API 598” and “Rate A” wording is one of the most common documentation review comments. The fix is simple: state both acceptable standards in the RFQ line.
Foire aux questions
Is EN 12266 Rate A stricter than API 598?
For soft-seated valves they are effectively equivalent (no visible leakage). For metal-seated valves the comparison depends on size and the rate class specified — check the numbers, not the names.
Do I need a witness test?
Standard practice is a manufacturer test with certificates. Third-party witnessed testing (per your inspection level) is specified separately — common on critical service and large-bore orders.
What documents should I receive?
Test certificates referencing the standard and acceptance class, plus EN 10204 3.1 material certs. See our guide to API 600 gate valves for typical documentation packages.
Need valves tested and certified to your project standard? Send ValveAtlas your datasheet.
