The short distinction
API 602 is titled for gate, globe and check valves through DN 100 (NPS 4). It covers the compact small-bore family and can be associated with threaded, socket-weld, butt-weld and flanged arrangements where the selected edition and design permit them.
API 600 covers steel gate valves with flanged or butt-welding ends and bolted bonnets. Confirm the requested size, class and construction against the selected edition.
| Item | API 602 | API 600 |
|---|---|---|
| Valve families | Gate, globe and check | Gate |
| Published size statement | Through DN 100 (NPS 4) | Check the selected edition and project size range |
| Characteristic construction | Compact small-bore steel valve | Steel gate valve with bolted bonnet |
| End-connection emphasis | Multiple compact-valve end arrangements | Flanged and butt-welding ends |
| Typical specification role | Small-bore gate/globe/check valve class | Gate-valve class, commonly flanged or butt-weld |
There is an overlap zone
Nominal size alone does not settle every case. A flanged gate valve within the API 602 size range may also sit inside a project’s API 600 purchasing practice. The piping class may deliberately choose one construction to standardise face-to-face dimensions, bonnet form, spare parts or maintenance procedures.
When a requisition says “API 600/API 602”, ask which standard governs the valve and which standards govern only the ends, pressure rating and tests. A dual reference without precedence can leave body design, dimensions and documentation open to interpretation.
Installation dimensions can block a substitution
Two gate valves with the same NPS, Class and flange facing can have different face-to-face, overall height, handwheel position or bore geometry. Existing piping replacement work also needs an approved general-arrangement drawing.
For butt-weld ends, record pipe outside diameter, wall thickness or schedule, bore matching and bevel preparation. For flanged ends, record the flange standard, facing, mating flange and required face-to-face basis. An RTJ valve cannot be treated as an RF valve with a different gasket.
Bonnet wording is part of the standard choice
API 600 identifies a bolted-bonnet steel gate-valve family in its title. API 602 purchasing descriptions may call for bolted or welded bonnet constructions depending on the edition, valve type and project requirements. A pressure-seal bonnet is another construction; the pressure class does not identify it.
The bonnet form affects pressure-boundary joints, maintenance access, packing service and the documents required for repair. The quotation and datasheet should repeat the selected construction in plain language.
A defensible selection sequence
First read the project piping class and valve data sheet. Confirm valve function and size, then connection type, body material, pressure-temperature basis and bonnet. Only then select the product standard whose scope matches the complete description.
If replacement interchangeability is required, add measured installation dimensions and tag the approved drawing as a purchase document. If the project requires an API Monogram, check that condition separately from technical conformity.
- Use API 602 for an in-scope compact gate, globe or check valve when the project specifies that family.
- Use API 600 for an in-scope steel gate valve with the specified flanged or butt-weld ends and bolted bonnet.
- Escalate mixed references, unusual bonnet forms and replacement dimensional constraints for technical review.
Specification checks
- Give one product standard precedence; do not leave “API 600/API 602” unresolved.
- Confirm valve family, NPS/DN, class, body material and bonnet construction.
- Name flange, weld-end and face-to-face standards independently.
- Attach the existing-valve drawing or verified dimensions for replacements.
- Verify any Monogram requirement against the supplying facility and licensed scope.
Catalogue and RFQ
Standards publisher references
Published by Nordic Valves Ab Oy, the operator of FerraForge. These links describe the publishers’ official scope. Purchase documents must state the edition required by the project and include any amendments or owner specifications.
- API Standard 602, 11th Edition programme noticeAmerican Petroleum Institute · Official API notice confirming the edition and gate, globe and check valve scope through DN 100 (NPS 4).
- API Standard 600, 14th Edition programme noticeAmerican Petroleum Institute · Official API notice confirming the steel gate valve standard edition and title.
- API Monogram and APIQR programme documentsAmerican Petroleum Institute · Official standard titles and the API Monogram programme document register.
- API Monogram programme updatesAmerican Petroleum Institute · Edition notices, errata and programme updates for API product standards.
- ASME B16.34 - Valves - Flanged, Threaded, and Welding EndASME · Official scope covering valve pressure-temperature ratings, materials, dimensions, testing and marking.
- ASME B16.10 - Face-to-Face and End-to-End Dimensions of ValvesASME · Official scope for valve installation dimensions by material, type, size, rating class and end connection.