API 607 and ISO 10497: What a Fire-Safe Valve Certificate Covers

A fire-safe valve certificate is a type test on a design, and it measures four things: through-seat leakage, external leakage, cavity overpressure relief on double-seated valves, and operability. That is the scope ISO 10497:2022 sets for itself, in its own words.

It also sets the rules by which a qualification on one valve is extended to untested sizes, pressure ratings and materials of the same basic design type — which is why the certificate in your hand may never have burned the valve you are buying.

This article sets out which standard applies to which valve, what the four criteria mean, what the certificate does not cover, and what to ask a supplier for instead of the words "fire safe".

Read it and you can tell a fire-test certificate that covers your valve from one that covers its cousin.

What does a fire test actually measure?

It measures four things — through-seat leakage, external leakage, cavity overpressure relief of double-seated valves, and operability — under a scope that excludes most actuators.

ISO 10497:2022 specifies fire type-testing requirements and a fire type-test method for soft- and metal-seated isolation valves with one or more obturators, and it specifies measurement and assessment criteria for through-seat leakage, external leakage, cavity overpressure relief of double-seated valves, and operability.

Its own scope also states an exclusion that matters more than buyers expect: the document is not applicable to the testing requirements for valve actuators other than manually operated gearboxes or similar mechanisms forming part of the normal valve assembly. Electrical, pneumatic and hydraulic actuators can need special protection in that environment, and the fire testing of such actuators is outside the scope of the document.

That single line decides a common argument. A fire-tested valve with an electric actuator has had the valve tested, not the assembly. Where the assembly has to survive, the actuator protection is a separate requirement on a separate document.

Which standard applies to which valve?

Three names appear on specifications — API 607, API 6FA and ISO 10497 — and they are not interchangeable, because each is written around a different group of valves.

ISO 10497:2022 also states how older evidence is treated: fire test reports of valves tested to previous editions are acceptable when submitted together with the full and compliant fire test report required by the edition under which it was tested, and any data missing from that report is accepted or rejected at the purchaser's discretion. So a certificate to ISO 10497:2010 is not automatically invalid — but it is only as good as the report that comes with it.

Why does a soft-seated valve need a second seat?

Because the seat that makes the valve tight is the part the fire destroys.

A soft-seated ball valve seals on a polymer — PTFE, PEEK or an elastomer. In a fire, that material degrades. What the fire test asks is whether the valve still holds a pressure boundary and a controlled leak path once the soft seat is gone. The design answer is a metal backup seating surface that takes over, and graphite packing behind the primary stem packing, which retains sealing at temperatures far above the polymer's range.

On a double-seated valve there is a third question the test asks directly: whether pressure trapped in the body cavity, by thermal expansion or vaporisation, is relieved rather than left to rupture the body. That is the third of the four criteria.

The certificate therefore describes a construction, not just a result. A fire-safe valve is a valve with a secondary metal seat, high-temperature packing and, where the design is double-seated, a cavity relief path. None of those are visible on a datasheet that only says "fire safe".

What does the certificate not cover?

It does not cover fugitive emissions, production release, the actuator, cryogenic or high-temperature service, or how long the valve survives.

It is not a fugitive emissions test. Fire testing measures leakage under flame and after cool-down. Low-emission performance in normal service is a different test with different classes and its own certificate — see this site's ISO 15848 article. A valve can hold one and not the other.

It is not a production release. It is a type test. The standard's own extension rules allow the qualification to cover untested sizes, pressure ratings and materials of the same basic design type, which is precisely why the qualified range has to be read, not assumed.

It does not cover the actuator, beyond a manually operated gearbox forming part of the assembly.

It does not cover cryogenic or high-temperature service. A fire test is a short, extreme event. It says nothing about −196 °C or about 600 °C in normal operation.

It is not a statement about how long the valve survives. The criterion is leakage and operability through and after a defined exposure, not survival for a defined period in a real fire.

Who has put what on the record?

Both sides are on the record: the standard's own scope on the one hand, and the Chinese laboratories that publish the tests they can run on the other.

The practical point for a buyer of Chinese valves: fire-safe testing capacity exists domestically, which shortens the route to a certificate. It does not change what the certificate says. Ask for the standard and edition, the qualified size and class range, and the report.

Where does this route stop?

A fire test qualifies a design under a defined exposure. It does not qualify a valve for a duty, and it does not qualify a plant.

Three limits follow. The qualified range is a range — a valve outside the tested size, class or material combination is outside the qualification even if it looks identical. The design has to be unchanged from the tested configuration; a seat material substitution is a new question. And the test says nothing about what the process requires: a fire-tested valve that cannot hold the shut-off class the duty needs has passed a test and still failed the service.

What does the trend add up to?

Two movements, both visible in the public record: the international standard was reissued in 2022 and now states in one place what counts as evidence from earlier editions, and domestic testing capacity in China has grown to the point where fire-safe testing is a local service rather than an overseas one. The first makes older certificates easier to assess; the second makes them cheaper to obtain. Neither changes the fact that the certificate documents a design family, not a valve.

When does this go to a human?

Five boundaries for fire-safe enquiries: any duty below −101 °C (−150 °F), where automatic coverage ends unconditionally; any requirement that names "fire safe" without naming the standard and edition; any assembly where the actuator, not just the valve, has to be qualified; any duty above 425 °C (797 °F), where the body material group moves; and any duty at DN1200 or above, or above Class 2500 or 420 bar.

• Any duty below −101 °C (−150 °F), where this site's automatic coverage ends unconditionally
• Any specification that says "fire safe" and does not name the standard, the edition and the qualified size and class range
• Any enquiry where the actuator, rather than the valve alone, has to hold a fire performance requirement
• Any duty above 425 °C, and any duty above 538 °C without exception
• Any duty at DN1200 or above, or above Class 2500 or 420 bar

What people assume, and what the record says

Common questions about fire-safe valves

Which standard should I name — API 607 or ISO 10497?

Name the one your project specification recognises, with its edition. API 607 is written around quarter-turn valves and non-metallic seats; ISO 10497 covers soft- and metal-seated isolation valves. Where the valve is an API 6A or 6D valve, the fire-test route is API 6FA.

Does a metal-seated valve need a fire test?

The need is set by the hazard analysis, the code and the owner's specification, not by the seat material. ISO 10497:2022 covers both soft- and metal-seated isolation valves, and the criteria still include through-seat leakage and operability.

Can I use a certificate that covers a different size?

Only if the size falls inside the qualified range stated in the report. The standard's extension rules are the reason that range has to be read rather than assumed.

Is a fire test the same as a fugitive emissions test?

No. One measures leakage during and after flame exposure; the other measures leakage to atmosphere in normal service at the stem and body joints.

What this article does not cover

Note that this article does not perform a fire hazard analysis, does not determine whether a valve or an installation complies with any standard, regulation or owner specification, does not select or size an actuator or its fire protection, and does not provide certification or qualification advice. It records the scope of ISO 10497:2022 and the API fire-test routes, and states what a fire-safe certificate does and does not assert.

Where the next constraint sits

A fire test and a low-emission test are two certificates on the same valve, and buyers routinely ask for one when they mean the other. What the four fields on a low-emission certificate claim, and why a tightness class alone is not a specification, is set out in ISO 15848 Explained: Reading BH, CO3 and SSA0 on a Valve Certificate.

The other reason a fire-safe design exists is the seat: a soft seat that seals in normal service is the part a fire removes, and the metal seat that replaces it is the one that sets the temperature ceiling and the achievable tightness. Soft-Seated vs Metal-Seated Valves: Where the Temperature Line Is sets out where that line sits.

The ball valve is the construction the fire question lands on most often — its seat options and the floating-to-trunnion fork: Ball Valves.

Sources