Valve Casting Standards: ASTM, API & ISO

Cast valve bodies are pressure-boundary parts, so they are governed by a stack of standards — ASTM for the casting material, API and ASME for the valve design and rating, and dedicated test standards for proving integrity. Here is how those standards fit together.

Reviewed by Matson Foundry engineering · Published 15 June 2026 · Last updated 15 June 2026

Direct answer: Cast valves are governed by three layers of standards. ASTM material specs define the casting alloy — A216 (carbon steel), A352 (low-temperature), A217 (high-temperature alloy) and A351 (stainless, CF8/CF8M). API and ASME standards set the valve design and rating — API 600/602/6D for construction and ASME B16.34 for pressure-temperature class. Test standards such as API 598 (pressure/seat test) and API 607 (fire test) prove integrity of the finished valve.

The Three Layers of Valve Casting Standards

It helps to read valve casting standards as three layers that stack from the metal up to the finished, tested valve. First, an ASTM material specification defines what the casting is made of and how strong it must be. Second, a valve design standard (API or ASME) defines how the body is built and what pressure-temperature rating it carries. Third, a test standard defines how the finished valve is inspected and proven. A complete valve callout names one from each layer — for example, an A216 WCB body, built to API 600, rated per ASME B16.34, tested to API 598.

Cast steel valve body governed by ASTM, API and ASME standards — A finished cast valve body — its material, rating, and testing each trace to a separate standard.

Layer 1: ASTM Material Standards

The casting material is set by an ASTM specification that fixes chemistry, mechanical properties, heat treatment, and required testing. For valve bodies the common specs split by service temperature and corrosion resistance, per ASTM International:

ASTM Spec	Common Grades	Typical Service
A216	WCB, WCC	Carbon steel, ambient to moderate temperature, general service
A352	LCB, LCC, LC3	Low-temperature carbon/alloy steel, impact-tested for cold service
A217	WC6, WC9, C5, C12	Alloy steel for high temperature and creep (power, refinery)
A351	CF8, CF8M, CF3, CF3M	Austenitic stainless for corrosive and stainless duty

For full chemistry and mechanical data on these grades, see our casting alloy comparison chart and the valve casting material options.

Layer 2: API & ASME Design Standards

Design standards define how the valve is built and what it is rated for. The American Petroleum Institute publishes the construction standards for industrial valves, while ASME B16.34 governs the pressure-temperature rating that the casting material must support.

Standard	Scope
API 600	Bolted-bonnet cast steel gate valves, generally NPS 2 and larger, refinery/pipeline service
API 602	Compact steel gate, globe and check valves, generally NPS 4 and smaller
API 6D	Pipeline and pipeline-related valves (ball, gate, check, plug)
API 608	Metal ball valves, flanged, threaded and welding ends
ASME B16.34	Pressure-temperature ratings, wall thickness and material rules (Class 150–2500)

ASME B16.34 is the bridge between the material layer and the rating: it ties a grade such as A216 WCB to an allowable pressure class across temperature, and it sets minimum wall thickness for the cast body.

Layer 3: Inspection & Test Standards

A cast valve is only acceptable once its pressure boundary is proven. API 598 defines the inspection and testing regime — hydrostatic shell test, seat test, and backseat test — with allowable leakage rates by valve type and size. For safety-critical service, API 607 (and API 6FA) fire-test soft-seated quarter-turn valves to confirm they stay sealed during and after fire exposure. Casting soundness is verified before assembly with NDT: dye-penetrant or magnetic-particle for surface defects, and radiographic or ultrasonic testing for internal soundness, with acceptance levels referenced to ASTM E446/E186.

Inspection and pressure testing of cast valve assemblies per API 598 — Finished valve assemblies undergo hydrostatic and seat testing to API 598 before shipment.

Reading a Complete Valve Casting Callout

Putting the layers together, a typical specification for a cast gate valve might read: cast carbon steel body to ASTM A216 Grade WCB, valve to API 600, rated Class 300 per ASME B16.34, pressure-tested to API 598. Each clause locks a different requirement — alloy, construction, rating, and proof testing — and the foundry must satisfy all of them. Choosing the right ASTM grade is the foundation step: get the material wrong and the B16.34 rating and downstream testing cannot be met. For method selection behind these bodies, see our valve casting methods comparison.

Frequently Asked Questions

Which ASTM standards apply to cast valve bodies?

The core ASTM material specs are A216 (carbon steel, WCB/WCC for general service), A352 (low-temperature carbon and alloy steel, LCB/LCC/LC3), A217 (alloy steel for high temperature, WC6/WC9/C5/C12) and A351 (austenitic stainless, CF8/CF8M for corrosive service). Each defines chemistry, mechanical properties, heat treatment and testing for the casting.

What is the difference between API 600 and API 602?

API 600 covers bolted-bonnet cast steel gate valves for refinery and pipeline service, typically NPS 2 and larger. API 602 covers compact steel gate, globe and check valves, generally NPS 4 and smaller, often forged or cast for small-bore lines. The split is mainly size class and valve construction.

What is the difference between API 598 and API 607?

API 598 is the valve inspection and testing standard, defining hydrostatic shell, seat and backseat pressure tests for the finished valve. API 607 is a fire-test standard that verifies a soft-seated quarter-turn valve stays leak-tight during and after exposure to fire. API 598 proves pressure integrity; API 607 proves fire safety.

Does ASME B16.34 apply to cast valves?

Yes. ASME B16.34 sets the pressure-temperature ratings, wall-thickness minimums and material requirements for flanged, threaded and welding-end valves, including cast bodies. It ties the casting material grade (for example A216 WCB) to an allowable pressure class such as Class 150 to 2500 across temperature.

How is the casting material grade chosen for a valve?

Match the alloy to service temperature and corrosion. A216 WCB suits ambient-to-moderate temperatures; A352 grades handle low temperature without brittle fracture; A217 alloy grades cover high-temperature and creep service; A351 CF8/CF8M handle corrosive or stainless duty. The chosen grade then sets the B16.34 pressure rating.