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In North America, valve requirements are defined by multiple complementary standards that cover design, ratings, leakage acceptance, fire-safety, emissions, and waterworks performance.

ASME B16.34 — Design, materials, wall thickness, P–T ratings, marking, baseline tests.
API 598 — General inspection and testing for isolation valves.
API 6D / ISO 14313 — Pipeline valve integrity (DBB/DIB, cavity relief, gas seat tests, torque).
MSS SP-61 — Common pressure-testing practice for steel valves.
FCI/ANSI 70-2 — Control valve leakage Classes II–VI.
API 607 / API 6FA — Fire tests; ISO 10497 global equivalent.
API 641 / 622 / 624 — Low-emission standards.
AWWA Series — Waterworks standards (C509, C515, C504, C507).

ASME B16.34 — THE CONSTRUCTION & RATING SPINE

ASME B16.34 covers metallic valves and defines pressure–temperature ratings, material groups, minimum wall thickness, marking, and baseline pressure tests.

Practical use:

Select material per chemistry and temperature.
Confirm P–T rating for worst-case condition.
Use ASME B16.5/B16.47 for flanges.

Spec line: “Valves shall conform to ASME B16.34 for design, materials, wall thickness, and P–T ratings.”

API 598 — THE EVERYDAY INSPECTION & TEST STANDARD

Defines hydrostatic shell and seat tests, low-pressure gas tests, backseat tests, and operational checks.

Acceptance:

Soft seats: zero visible leakage.
Metal seats: limited visible leakage allowed.
Check valves: specific criteria apply.

Engineer’s tip: shell test hydro, seat test per API 598, add low-pressure air test for soft seats.

API 6D — PIPELINE VALVES

Includes DBB/DIB verification, cavity relief, high-pressure gas seat tests, torque checks, and documentation requirements. Stricter than API 598.

Spec line: “Pipeline valves shall meet API 6D, verify DIB as specified, cavity relief, gas seat tests, torque.”

MSS SP-61 — STEEL VALVES TESTING

Standard pressure-testing practice for steel valves. Commonly used where API 598 is not mandated and often paired with ASME B16.34.

FCI/ANSI 70-2 — CONTROL VALVE SHUTOFF

Defines Classes II–VI for control valve seat leakage. Class IV is typical default; Class V/VI used for demanding services.

Spec line: “Control valve shutoff shall meet FCI 70-2 Class IV unless otherwise specified.”

FIRE-SAFE TESTING

Fire test standards include API 607, API 6FA, and ISO 10497. Valves are exposed to fire while pressurized to measure primary and secondary leakage.

Spec line: “Valves in hydrocarbon service shall be fire-tested per API 607 or API 6FA/ISO 10497.”

LOW EMISSIONS STANDARDS

Low-emission requirements include API 641 for quarter-turn valves, API 622 for packing, and API 624 for rising-stem valves.

Spec line: “Valves in VOC service shall meet API 641 or API 624 with API 622 packing.”

WATERWORKS — AWWA

AWWA standards apply to potable water valves and differ from API/ASME in pressure classes, coatings, torque expectations, and service conditions.

FACTORY ACCEPTANCE TESTS (FATs)

Hydrostatic shell test ~1.5× rating.
Directional hydro seat test.
Low-pressure air seat test (soft seats).
Backseat test (if provided).
Operational/torque checks.
Special tests: fire-safe, FE, cryogenic, vacuum, DBB/DIB.

ACCEPTANCE & DOCUMENTATION

Soft seats: zero leakage.
Metal seats: limited leakage per API/ISO.
MTCs, calibrations, test records, markings, fire-safe/FE certificates.

API VS EN/ISO DIFFERENCES

API focuses on procedural testing and visual acceptance, while EN/ISO uses numeric leakage classes. Projects often blend the two.

Example: “Shell per API 598; Seat per ISO 5208, Rate A.”

EXAMPLE SPECIFICATION LANGUAGE

Isolation valves: ASME B16.34 design, API 598 tests, ISO 5208 leakage rates.
Pipeline valves: API 6D, DBB/DIB, cavity relief, gas seat tests.
Control valves: IEC 60534-4, FCI 70-2 Class IV.
Fire-safe: API 607/6FA/ISO 10497.
Low emissions: API 641/624/622.
Waterworks: AWWA + NSF coatings.

COMMON PITFALLS

Over-specifying Class VI for control valves.
Skipping gas seat tests for gas service.
Confusing DBB vs DIB terminology.
Not specifying soft-seat air test.
Mixing AWWA with API without caution.

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