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What is the difference between API 600 and API 602?
The two standards are separated by size band and by which valve families they cover, not by how the body was made. API 600 is a heavy-duty bolted bonnet gate valve standard running up to DN 1050; API 602 is a compact standard that stops at DN 100 and covers gate, globe and check valves together. Everything below comes from the publishers’ and distributors’ catalogue records for the two documents. The standards’ own body text is neither read nor reproduced here.
Flowsynergy Solutions Limited supplies gate, globe, check, ball, butterfly and knife-gate valves from Level 41, Emirates Towers, Sheikh Zayed Road, Dubai, with valve selection and technical support alongside the supply. Have a line schedule or a datasheet with a standard call-out on it? Our technical support can talk it through with you: call +971 4 313 2786, write to enquiry@flowsynergy.ae, or use the enquiry form, Monday to Friday, 8:30 am to 5:00 pm Dubai time. The wider picture is in our guide to valve selection by standard and service condition.
What does API 600 cover?
API 600 is the heavy-duty bolted bonnet steel gate valve standard, and its own scope annotation says so in those terms. The catalogue record for API STD 600, fourteenth edition, May 2021, held by the standards distributor NORMSERVIS, describes a standard that "specifies the requirements for a heavy-duty series of bolted bonnet steel gate valves for petroleum refinery and related applications where corrosion, erosion, and other service conditions would indicate a need for full port openings, heavy wall sections, and large stem diameters".
The same record lists the features the standard sets requirements for: bolted bonnet, outside screw and yoke, rising stems, non-rising handwheels, single or double gate, wedge or parallel seating, metallic seating surfaces, and flanged or butt-welding ends. Read as a list, that describes a construction rather than a manufacturing route. On size and rating the record states nominal sizes DN 25 through DN 1050, corresponding to NPS 1 through NPS 42, and class designations 150, 300, 600, 900, 1500 and 2500. DIN Media's record for API STD 600 marks the standard current and shows it as "FOURTEENTH EDITION, MAY 2021; ERRATA 1, APRIL 2024" at 42 pages.
What does API 602 cover?
API 602 is a compact valve standard, and its title names three valve families, not one. The NORMSERVIS catalogue record for API STD 602, eleventh edition, May 2022 gives the title as Gate, Globe, and Check Valves for Sizes DN 100 (NPS 4) and Smaller for the Petroleum and Natural Gas Industries, and states that it "specifies the requirements for a series of compact gate, globe, and check valves for petroleum and natural gas industry applications". Do not read API 602 as a gate-only document: its title names three families.
The same record puts the size scope at nominal sizes DN 8 through DN 100 and the class designations at 150, 300, 600, 800 and 1500, and adds a note worth reading twice: "Class 800 is not a listed class designation, but is an intermediate class number widely used for welded and threaded end compact valves." It also states that the standard applies to end flanges in accordance with ASME B16.5, tapered pipe threads to ASME B1.20.1 and socket weld ends to ASME B16.11.
Is the difference cast against forged?
No. Neither published title, and neither scope annotation quoted above, uses the word cast or the word forged. API 600's title names a material family (steel), the end connections and the bonnet type; API 602's names the valve families and a size ceiling. It is not what either document is scoped by, and a requisition written on it can name the wrong standard.
Where do the two scopes overlap?
From DN 25 to DN 100, which is NPS 1 to NPS 4, both standards' stated scopes apply. API 600's record starts its size list at DN 25 and API 602's ends at DN 100, so small bore sits inside both documents. A line reading "2 inch gate valve, class 300" has not said which standard governs. Several widely read pages put API 602's ceiling at NPS 2. The eleventh edition's own title says DN 100 (NPS 4) and smaller, so the band the two documents share is wider than those pages suggest.
| In its catalogue record | API STD 600 | API STD 602 |
|---|---|---|
| Edition shown | Fourteenth, May 2021, with Errata 1 of April 2024 | Eleventh, May 2022 |
| Valve families in the title | Gate valves | Gate, globe and check valves |
| Size scope stated | DN 25 to DN 1050, NPS 1 to NPS 42 | DN 8 to DN 100, NPS 4 and smaller |
| Class designations stated | 150, 300, 600, 900, 1500, 2500 | 150, 300, 600, 800, 1500 |
| Named in the title | Flanged and butt-welding ends, bolted bonnets | A size ceiling, and the petroleum and natural gas industries |
| What its own scope annotation says it is for | Petroleum refinery and related applications needing full port openings, heavy wall sections and large stem diameters | Compact valves for petroleum and natural gas industry applications |
The two class lists diverge at both ends: they share 150, 300, 600 and 1500, Class 800 appears only in API 602's, and Classes 900 and 2500 only in API 600's. Whether globe and check valves are wanted on the same line also separates them, because API 602 covers all three families and API 600 does not. How a Class attaches to a pressure and temperature rating is set out in our guide to ASME B16.34 pressure and temperature ratings. The step before this one, whether a gate valve is the right type at all, is in our comparison of gate, ball and butterfly valves for isolation.
Where does ISO 10434 fit?
ISO 10434 covers the same subject as API 600, and the two catalogue annotations run nearly word for word. BSI's record for BS EN ISO 10434:2020, published 30 September 2020 and marked current, gives a scope that runs word for word with API 600's, down to the same "full port openings, heavy wall sections, and large stem diameters" and the same eight valve features. The one wording difference is that those conditions "can indicate" the need, where API 600's record says "would indicate".
What differs on a Gulf project is the size ceiling and the designation system. BSI's record states a size scope of DN 25 to DN 600, which is NPS 1 to NPS 24, where API 600's record runs to DN 1050. It also states that ISO 10434 applies for PN designations 16 through 400 as well as for Class designations, with the higher PN and Class designations added in this edition, where API 600's record states Class designations only. Where a schedule written in PN meets a specification written in Class, that is the difference that surfaces: our guide to reading PN and Class on a call-out sets out how the two systems work.
What does the purchase order have to name?
A gate valve line needs the standard, the edition, the size, the class, the end connection and the body material. Naming API 600 settles the bonnet and the construction family, but not the material grade, and a size inside the overlap band settles nothing on its own. BSI records BS EN ISO 10434:2020 as superseding BS EN ISO 10434:2004, which is withdrawn, so an old drawing note can point at a document that no longer exists. The project specification's named edition governs the order, and the current catalogue record, or the issuing body's own listing, is what to check before it is placed.
Flowsynergy offers valve selection and technical support, supply of valves and fittings, and valve testing, maintenance and repair. Send the schedule or the datasheet and our technical support can go through the call-out with you: +971 4 313 2786 or enquiry@flowsynergy.ae. What the paperwork should arrive with is in our guide to valve documentation a buyer should demand, and what an API monogram on a valve actually proves covers the marking that follows.
Questions buyers ask about API 600 and API 602
Is ISO 10434 an acceptable substitute for API 600?
That is the project specification's call: neither catalogue record states the two documents are equivalent. What they do show is where the scopes differ. BSI's record puts ISO 10434 at DN 25 to DN 600 against API 600's DN 25 to DN 1050, and gives ISO 10434 PN designations as well as Class. Above DN 600 the two are not interchangeable on scope alone.
The drawing names API 600 with no edition. What should the requisition say?
Ask the specifier which edition the project is built to and put that year on the requisition, because a bare standard number leaves the supplier to choose. If no answer comes back, state the edition you are quoting against so the basis is on the order: DIN Media currently shows API STD 600 as the fourteenth edition of May 2021 with Errata 1 of April 2024.
Can an API 602 valve be supplied against an API 600 line between DN 25 and DN 100?
Only if the specification allows it, and the two catalogue records do not settle that between them. They show the scopes meeting in that band, not that a valve to one document satisfies the other. The class lists are where the two records visibly diverge: a line calling for Class 900 or Class 2500 is outside API 602's stated class designations altogether. Put the question to the specifier rather than to the supplier, and record the answer on the order.
Does API 602 cover a small bore ball or butterfly valve?
No. API 602's title names gate, globe and check valves, so a ball or butterfly valve needs its own standard even at DN 50. For butterfly valves, see our guide to API 609 Category A and Category B. We supply all of these families, so the practical step is to tell us the duty and let the standard follow.
Sources: the records quoted on this page
Read 16 October 2026. Every quotation above comes from one of these four records. Three are standards distributors' catalogue records (NORMSERVIS twice and DIN Media) and one is BSI's. None of the standards' own tables, dimensions or test values is reproduced here.
- The catalogue record for API STD 600, fourteenth edition, May 2021, held by the standards distributor NORMSERVIS: the title, edition, date and page count, the scope annotation, the feature list, the size scope and the class designations.
- DIN Media's record for API STD 600: the current marking and the "FOURTEENTH EDITION, MAY 2021; ERRATA 1, APRIL 2024" line.
- The catalogue record for API STD 602, eleventh edition, May 2022, same distributor: the title, the scope annotation, the size scope, the class designations, the Class 800 note and the ASME end connection references.
- BSI's record for BS EN ISO 10434:2020: the title, the 30 September 2020 publication and current status, the scope wording, the feature list, the size scope, the Class and PN designations, this edition's changes and the superseded 2004 edition.
Reference information only. Nothing on this page is a claim that Flowsynergy stocks a particular valve, is accredited to any of these standards, or performs testing to them.