USED FOR:
(Parts 1–2) Industrial valves – Measurement, test and qualification procedures
Classifying valve stem and body-joint sealing performance for fugitive (VOC/methane) emissions — Part 1 covers type testing, Part 2 covers production acceptance testing.
RELATED STANDARDS:
- API 624 “Type Testing of Rising Stem Valves Equipped with Graphite Packing for Fugitive Emissions”
- API 641 “Type Testing of Quarter-turn Valves for Fugitive Emissions”
- API 622 “Type Testing of Process Valve Packing for Fugitive Emissions”
- EPA Method 21 “Determination of Volatile Organic Compound Leaks (US regulatory reference method)”
DIMENSIONAL RANGE:
This isn’t a dimensional standard in the classic NPS/DN sense either: the tightness, temperature and endurance classes ISO 15848-1 defines apply independently of the valve’s nominal size or pressure class. What actually governs size coverage is a qualification-extension rule rather than a size table, once a valve passes the type test, that qualification can be extended to untested sizes of the same design as long as the stem or shaft seal geometry and materials stay the same and the untested stem diameter falls between half and twice the diameter that was actually tested. We treat that ratio, not a DN or Class figure, as the real boundary condition when deciding whether an existing type-test certificate covers a specific valve on our piping class list
DESCRIPTION:
Valves are tested and classified by tightness class (A, B, C), temperature class, and endurance class, using helium or methane as the test medium through repeated thermal and mechanical cycling. On any project with environmental emissions targets, increasingly common, this is the specification we attach to valve stem-packing requirements rather than relying on the manufacturer’s generic claims.
IMPORTANT NOTES:
ISO 15848-1 and API 641/624 are not directly comparable, different test media options, temperature ranges, and pass/fail thresholds mean a valve “compliant” under one is not automatically compliant under the other; specify which standard applies explicitly.
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