Industrial valve RFQs are full of codes: API 600, API 602, API 623, ASME B16.34, Class 150… If you are new to process valves — or you buy UL/FM fire protection products and are expanding into industrial lines — here is what the main API design standards actually mean when you place an order.
API Standards Are Design & Construction Rules
The American Petroleum Institute (API) publishes valve standards that fix wall thickness, stem diameter, materials, testing and dimensions, so that a “Class 300 API 600 gate valve” from any compliant manufacturer is mechanically equivalent. The project engineer specifies the standard; the buyer’s job is to make sure the quoted valve genuinely complies.
The Big Three for Steel Valves
API 600 — Bolted-Bonnet Cast Steel Gate Valves
The workhorse standard for cast steel gate valves NPS 1–24 and larger, Class 150–2500. Key buyer points: full-bore wedge design, renewable seat rings, OS&Y rising stem, and minimum wall thickness heavier than ASME B16.34 alone requires.
API 602 — Compact Forged Steel Valves (NPS ≤ 4)
Small-bore forged gate, globe and check valves in A105, LF2 or F316L — the thousands of small valves around pumps, instrument roots and drains. Bonnet options matter here: bolted, welded, or pressure-seal.
API 623 — Steel Globe Valves
The globe-valve companion to API 600: heavier walls than generic B16.34 globes, defined trim numbers, and standardized face-to-face so they drop into the same line.
Codes You See Next to Them
- ASME B16.34 — the base pressure-temperature rating code nearly all steel valves reference.
- ASME B16.10 — face-to-face dimensions (interchangeability in the pipe rack).
- API 598 — shop pressure testing: shell test and seat leakage acceptance.
- NACE MR0175 / ISO 15156 — sour (H2S) service material rules.
- ISO 15848-1 — fugitive-emission (stem leakage) type testing.
What This Means for Your RFQ
A clean industrial valve inquiry states: size, ASME class, standard (e.g. API 600), body/trim materials, end connections, operator, and any overlays — NACE, fire-safe (API 607), cryogenic (BS 6364), or low-emission (ISO 15848-1). With those eight items, any competent supplier can quote in one pass, with datasheets you can submit to the end client.
Frequently Asked Questions
Is API 600 “better” than ASME B16.34?
They are complementary. B16.34 gives pressure-temperature ratings; API 600 adds gate-valve-specific construction minimums on top of it.
Can I use API 602 valves above NPS 4?
API 602 formally covers NPS 4 and smaller. Above that, specify API 600 (gate) or API 623 (globe) cast valves.
Do these standards fix the price?
No — material grade, bonnet type, trim and origin drive cost. Same standard, very different price points; that is why we quote project-by-project.
Need API 600/602/623 valves with full documentation for Canada, the US, or export markets? Send us your valve list.
