A forged steel gate valve for small-bore piping is normally specified to API 602, whose current eleventh edition covers NPS 1/4 to 4 (DN 8 to 100) in Class 150, 300, 600, 800 and 1500. In the tenth edition's scope, the size limit depends on the configuration: socket-weld and threaded ends stop at NPS 2 1/2 (DN 65) and come only in Class 800 and Class 1500, and flanged Class 800 is excluded. Class 800 is an intermediate class, not a listed ASME B16.34 class. For forged A105 and A350 LF2, Emerson's ASME B16.34 bulletin prints 136.2 bar (1975 psig) at -29 to 38 °C (-20 to 100 °F). Name the API 602 edition, the configuration, the class, the end standard, the body grade, the trim number and the test standards on the datasheet.

A small-bore forged steel gate valve is usually specified to API 602, whose tenth-edition scope limits size and class by configuration. In that scope, socket-weld and threaded ends stop at NPS 2 1/2 (DN 65) and come only in Class 800 and Class 1500. Class 800 with flanged ends is excluded. Buyers confirm each limit against the current eleventh edition. Class 800 is an intermediate class, not a listed ASME B16.34 class. Emerson's ASME B16.34 bulletin prints 136.2 bar (1975 psig) for Class 800 in forged A105 and A350 LF2 at -29 to 38 °C (-20 to 100 °F).

This guide is for procurement and project engineers writing line lists or RFQs for small-bore forged gate valves in refinery, petrochemical, oil and gas or utility piping. They choose forged or cast bodies, the API 602 configuration and Class 800 or Class 1500. They check ends against ASME B31.3, including the socket-weld gap, and specify the bonnet and backseat. Body grades include A105, A350 LF2, F11, F22, F304, F316 and F51. Trims include API Trim 5, 8, 12 and 16. The order names API 598, API 622 and API 624 tests, plus NACE MR0175 / ISO 15156 for sour service.

• API 602's tenth edition limits size by configuration. Socket-weld, threaded and ISRS valves stop below the OS&Y flanged size ceiling.
• Class 800 is an intermediate class. Its ratings are linearly interpolated between ASME B16.34 Class 600 and Class 900 ratings.
• API 602's tenth edition excludes flanged Class 800. Order Class 800 with socket-weld, threaded or butt-weld ends.
• Forging does not raise the printed rating. At ambient, Emerson prints one Class 800 value for WCB and A105.
• Write the trim number with its materials. Trim 8 pairs a 13Cr wedge with a CoCr-hardfaced seat.
• Name each test standard and edition. API 598 pressure tests; API 622 packing and API 624 valve type tests.
• Sour service is a requirement set. Name NACE MR0175, or MR0103 for refineries, and ask for hardness records.

• TL;DR
• Abstract
• Key Takeaways
• Forged Steel Gate Valve: What It Is and How It Differs From a Cast Valve
• Glossary
• API 602 Gate Valve Scope: Sizes, Classes and Configurations
• Gate Valve Class 800: Where the Rating Comes From
• End Connections: Socket Weld, Threaded, Butt Weld and Flanged
• Bonnet, Stem and Backseat on a Forged Gate Valve
• Forged Body Materials by Service: A105, A350 LF2, F11, F22 and F51
• API Trim Numbers 5 and 8 for Forged Gate Valves
• Testing and Emissions: API 598, API 622 and API 624
• Forged Steel Gate Valve RFQ Checklist
• Frequently Asked Questions
• Conclusion
• References

A forged steel gate valve is a compact gate valve whose body and bonnet are steel forgings, such as ASTM A105 or A350 LF2, not castings such as A216 WCB (Emerson, 2017). It is usually specified to API 602, whose current eleventh edition covers NPS 4 (DN 100) and smaller (American Petroleum Institute, 2022).

If the valve type is not yet chosen, start with the gate valve vs ball valve comparison.

For the grades in this table, grade and product form change; the printed rating does not.

For WCB against A105 or A350 LF2, forging changes the product form, not the ASME B16.34 material group or its printed rating; other cast and forged pairs can sit in different groups. API 602's tenth edition lists castings too, so a buyer who needs a forging writes "forged" and the ASTM forging grade on the datasheet. A casting is poured into a mold; a forging is shaped from solid steel.

A study of open-die forging of large steel ingots notes that as-cast voids may significantly affect the final product's mechanical properties (Harris et al., 2016). Its simulation found upsetting most effective for closing voids in core regions (Harris et al., 2016). It did not study a valve body, so it does not show that a forged valve body is stronger than a casting.

Bonney Forge's catalog describes its gate valve body and bonnet as forged steel, the body designed to the basic dimensional requirements of specifications such as API 602 and ASME B16.34 (Bonney Forge, n.d.).

A forged steel gate valve is a compact gate valve whose body and bonnet are steel forgings, such as A105, A350 LF2 or an ASTM A182 grade, rather than castings such as A216 WCB (Emerson, 2017), usually specified to API 602 for NPS 4 (DN 100) and smaller (American Petroleum Institute, 2022). Emerson's ASME B16.34 bulletin gives cast WCB and forged A105 and A350 LF2 the same Class 800 rating, 136.2 bar (1975 psig) at -29 to 38 °C (-20 to 100 °F) (Emerson, 2017).

• Compact valve: API 602's gate, globe or check valve of NPS 4 (DN 100) and smaller (American Petroleum Institute, 2022).
• OS&Y: outside screw and yoke; the tenth edition's scope names it outside screw with rising stems (American Petroleum Institute, 2015).
• ISRS: inside screw with rising stems, the tenth edition's other stem design (American Petroleum Institute, 2015).
• Extended body: a body with a threaded or welding end extension, as the figure titles in the tenth edition's Annex B show (American Petroleum Institute, 2015).
• Standard bore and full bore: the tenth edition's body seat openings, each with a minimum flow passageway table (American Petroleum Institute, 2015).

An API 602 gate valve is a compact gate valve of NPS 4 (DN 100) and smaller in Class 150, 300, 600, 800 or 1500 (American Petroleum Institute, 2022). Within that range, the tenth edition's scope gives each configuration its own size and class limits (American Petroleum Institute, 2015).

API 602's current edition is the Eleventh Edition, published in May 2022; Accuris lists the Tenth Edition as a historical version (American Petroleum Institute, 2022). The eleventh edition covers NPS 1/4 to 4 (DN 8 to 100) and pressure class designations 150, 300, 600, 800 and 1500 (American Petroleum Institute, 2022). Write the edition on the purchase order.

API's product page for the tenth edition (May 2015) sets size and class limits by configuration (American Petroleum Institute, 2015).

Taken together, the scope limits confine the NPS 4 (DN 100) ceiling to OS&Y valves with flanged or butt-welding ends. Socket-weld, threaded and ISRS valves stop at NPS 2 1/2 (DN 65), and extended-body valves at NPS 2 (DN 50). Class 150, 300 and 600 appear only with flanged or butt-welding ends, because socket-weld and threaded ends are listed only for Class 800 and Class 1500. These limits are the tenth edition's; confirm each against the eleventh edition in force.

Walworth's API 602 catalog lists its gate valves in NPS 1/4 to 2, with socket-weld or NPT ends in Class 800, 1500 and 2500 and RF or RTJ flanged ends in Class 150, 300, 600 and 1500 (Walworth, n.d.); Class 2500 is outside API 602's designations. Bonney Forge's 800 lb gate valve dimension tables reach NPS 3 in one figure and stop at NPS 2 in the others (Bonney Forge, n.d.). A maker's line can be narrower than the standard, so the datasheet names stem type, end connection, body type and bore, not only "API 602".

The tenth edition's scope provides for standard and full-bore body seat openings (American Petroleum Institute, 2015). The gate valves Shinjo supplies are specified on the same datasheet lines.

In API 602's tenth edition, OS&Y valves run NPS 1/4 to 4 (DN 8 to 100). Socket-welding or threaded ends and ISRS stems stop at NPS 2 1/2 (DN 65). Flanged or butt-welding ends run NPS 1/2 to 4 (DN 15 to 100). Extended bodies stop at NPS 2 (DN 50) (American Petroleum Institute, 2015). Confirm each against the eleventh edition in force.

Class 800 is an intermediate class, not a listed class designation, widely used for compact socket-weld and threaded valves (American Petroleum Institute, 2015). For forged A105 and A350 LF2, Emerson's ASME B16.34 bulletin prints 136.2 bar (1975 psig) at -29 to 38 °C (-20 to 100 °F) (Emerson, 2017).

Per API's product page for the tenth edition, "Class 800 is not a listed class designation, but is an intermediate class number widely used for socket welding and threaded end compact valves." (American Petroleum Institute, 2015)

The tenth edition prints its own Class 800 rating tables, Tables 2a to 2f; its product page shows no values (American Petroleum Institute, 2015). WerMac explains that API 602 and ISO 15761 derive Class 800 by linear interpolation: one third of the ASME B16.34 Class 600 rating plus two thirds of the Class 900 rating, including above 38 °C (100 °F) (WerMac, n.d.).

API 602 is the valve's design standard and ASME B16.34 its rating standard; the difference between API and ASME standards affects every line of the order. A line item reading "gate valve class 800, socket weld, A105" is not yet a specification.

Emerson's bulletin prints these ASME B16.34 ratings for forged A105 and A350 LF2 (Emerson, 2017); the end connections follow the tenth edition's scope (American Petroleum Institute, 2015).

Bonney Forge's catalog prints the same 1975 psig and 3705 psig for carbon steel Class 800 and Class 1500 at 38 °C (100 °F) (Bonney Forge, n.d.). It also prints Standard, Special and Limited Class rating tables, rates flanged-end valves Standard Class only and applies Limited Class ratings to weld-end and thread-end valves only (Bonney Forge, n.d.). A catalog Class 800 figure must name its basis.

Emerson adds that its tables must be used in accordance with the ASME standard, and that a governing code, such as the ASME Code for Pressure Piping, can add maximum-temperature and low-temperature limits (Emerson, 2017).

A line needs Class 1500 when its design pressure at the design temperature exceeds the Class 800 rating for the body's material group. Emerson's tables show the ratings falling as temperature rises (Emerson, 2017), so above ambient that rating is read from the Class 800 table of the API 602 edition in force. The higher class comes with a trade-off. Under the tenth edition's scope, moving to Class 1500 also removes ISRS stems, union-nut bonnets and bellows stem seals from the options (American Petroleum Institute, 2015); the buyer confirms these exclusions against the eleventh edition.

API's product page for API 602's tenth edition calls Class 800 an intermediate class, not a listed class designation, widely used for socket-welding and threaded compact valves (American Petroleum Institute, 2015). For forged A105 and A350 LF2, Emerson's ASME B16.34 bulletin prints 136.2 bar (1975 psig) at -29 to 38 °C (-20 to 100 °F) (Emerson, 2017).

Every gate valve decision in this guide, from the API 602 edition down to the trim number, ends up as one line on a datasheet, and each line narrows which configuration actually fits the job. Shinjo’s gate valve range is where those lines get checked against a real listing, for procurement and project engineers specifying against a datasheet or line list.

A forged steel gate valve's end connection sets its API 602 size and class range and decides where the piping code accepts the joint. The tenth edition of API 602 ties each end to a standard (American Petroleum Institute, 2015), and so does Bonney Forge's catalog (Bonney Forge, n.d.). The datasheet names the end and its standard.

Size and class limits quote the tenth edition's scope; confirm each against the eleventh edition in force.

ASME B31.3 (2018 edition) para. 314.1(a) says threaded joints should be avoided where crevice corrosion, severe erosion or cyclic loading may occur (American Society of Mechanical Engineers, 2018). Para. 314.1(b) allows no thread sealing compound on a threaded joint to be seal welded (American Society of Mechanical Engineers, 2018).

Para. 311.2.2(a) gives socket welded joints the same caution for crevice corrosion or severe erosion (American Society of Mechanical Engineers, 2018). Para. 311.2.2(c) bars socket welds larger than NPS 2 (DN 50) under severe cyclic conditions (American Society of Mechanical Engineers, 2018).

The tenth edition's scope excludes flanged Class 800 (American Petroleum Institute, 2015). Read with paras. 314.1(a) and 311.2.2(a), butt weld is the Class 800 end that avoids both cautions in crevice-corrosion or severe-erosion service.

ASME B31.3 Figure 328.5.2C sets minimum welding dimensions for socket welding components other than flanges, including a gap before welding (American Society of Mechanical Engineers, 2018).

Para. 328.5.1(f) of ASME B31.3 requires the welding sequence, procedure and any heat treatment of a welding end valve to preserve its seat tightness (American Society of Mechanical Engineers, 2018). Per Walworth's API 602 catalog, gate valves install in either flow direction but are not for flow modulation, which may erode the wedge and seats (Walworth, n.d.).

Warning: A pipe pushed to the bottom of the socket leaves no gap, so the weld procedure states the gap and the fit-up is checked before the first tack weld.

ASME B31.3 Figure 328.5.2C shows a gap of approximately 1.5 mm (1/16 in.) between the pipe end and the socket bottom before welding (American Society of Mechanical Engineers, 2018). For a socket-weld gate valve, the weld procedure states that gap, so the fit-up is checked against a written figure before the pipe is welded into the socket.

The tenth edition of API 602 lists bolted, welded, threaded-and-seal-welded and union-nut bonnet joints, plus two rising-stem constructions: outside screw and yoke (OS&Y) and inside screw with rising stem (ISRS) (American Petroleum Institute, 2015). The backseat is a seat in the bonnet that a shoulder on the stem mates with (Bonney Forge, n.d.). Seated, it relieves back pressure on the stem packing (Walworth, n.d.).

Each bonnet joint has its own class limit.

Shinjo supplies bolted-bonnet forged gate valves; Shinjo's forged bolted-bonnet gate valve page shows one.

Bonney Forge lists a body-bonnet pressure seal design among its special features (Bonney Forge, n.d.). The tenth edition's scope lists no pressure-seal joint, so the datasheet should name the valve's design standard. Shinjo's forged pressure-seal gate valve page shows a pressure-seal bonnet.

Bonney Forge describes its forged steel gate valves as OS&Y, with a rising stem, a non-rising handwheel and an integral backseat (Bonney Forge, n.d.). API 598's test table, as Wolseley Industrial reproduces it, requires a backseat test for gate and globe valves (Wolseley Industrial, n.d.). Operator data for a class and size comes as a torque chart for metal-seated gate valves.

A gate valve backseat seals the stem to the bonnet. On Bonney Forge's forged valves, an integral back seat shoulder on the stem mates with an integral backseat in the bonnet (Bonney Forge, n.d.). When fully seated, the backseat relieves back pressure on the stem packing, but Walworth does not recommend replacing packing under pressure (Walworth, n.d.).

Choose the body grade by design temperature and service. A105 suits general carbon-steel service; A350 LF2 suits low temperatures needing impact-tested steel. F11 or F22 suits higher temperatures, and stainless or duplex grades suit corrosive media. Sour service adds requirements to any grade.

Wolseley Industrial's valve materials chart lists A105 as the carbon steel forging, with a temperature range of -29 to 427 °C (-20 to 800 °F) (Wolseley Industrial, n.d.). Emerson's ASME B16.34 bulletin rates forged valves in columns headed "A105 & A350-LF2", F5, F11, F22, F304, F316, F304L and F316L (Emerson, 2017).

WerMac's reproduction of ASME B16.34 Table 2-1.1 footnotes A105, A216 WCB and A350 LF2: prolonged exposure above 425 °C (797 °F) may convert the carbide phase of the steel to graphite, which is permissible but not recommended for prolonged use (WerMac, n.d.). Bonney Forge's catalog also lists A105N (Bonney Forge, n.d.).

ASTM A350 covers carbon and low-alloy steel forgings, including valves, intended primarily for low-temperature service and requiring notch toughness testing (ASTM International, 2026a). Its impact tests set a minimum impact energy at a test temperature (ASTM International, 2026a). Emerson's bulletin adds that a valve used under an ASME code is subject to its low-temperature material rules (Emerson, 2017).

The datasheet names the minimum design metal temperature (MDMT) and asks for the impact test report.

ASTM A182 covers alloy and stainless forgings, including valves, for high-temperature service (ASTM International, 2026b).

F304 and F316 appear in Emerson's forged columns (Emerson, 2017) and Bonney Forge's materials menu (Bonney Forge, n.d.). Choosing between them is a corrosion decision the datasheet settles against the medium.

Shinjo supplies extended-body forged gate valves, and Shinjo's extended-body gate valve page lists body types A105, A182 F22, A182 F304(L) and A182 F316(L).

NACE MR0175 / ISO 15156 covers materials for use in H2S-containing environments in oil and gas production, and its Part 1 sets the general principles and the material selection and qualification procedures (SSM Alloys, n.d.). For refining, NACE MR0103 / ISO 17945 covers metallic materials resistant to sulfide stress cracking in corrosive petroleum refining environments, so a refinery line names whichever of the two its plant specification calls up. Per SSM Alloys, NACE MR0175 applies only to sour (H2S-containing) service; in sweet service, A105 needs no NACE compliance (SSM Alloys, n.d.). Its Part 2 covers carbon and low-alloy steels, with a typical maximum hardness of 22 HRC (250 HV) (SSM Alloys, n.d.).

SSM Alloys says the mill test certificate should include hardness test results, a chemical composition report and a heat treatment record, plus hydrogen-induced cracking (HIC) and sulfide stress cracking (SSC) test results where applicable (SSM Alloys, n.d.). Walworth's API 602 catalog lists NACE MR0175 or MR0103 service among its features (Walworth, n.d.). Wolseley Industrial's bolting chart, which carries NACE MR0175 and MR0103 columns, lists A193 B7M bolts with A194 Grade 2HM nuts, beside B7 with 2H, for A105 and WCB bodies (Wolseley Industrial, n.d.). Global Supply Line's trim chart pairs specially treated 316 or 410 trim with B7M bolts and 2HM nuts to meet NACE MR0175 requirements (Global Supply Line, 2023).

Sour service is therefore a requirement set, not a grade. The datasheet states H2S-containing service and the standard the plant specification calls up, NACE MR0175 / ISO 15156 or NACE MR0103 / ISO 17945, with its edition. It asks for hardness and heat-treatment records for body, bonnet and trim, and names the NACE-listed bolting for the body grade, such as B7M bolts with 2HM nuts on an A105 body.

Forged steel gate valve body grade follows the service: A105 for general carbon-steel service (Wolseley Industrial, n.d.), A350 LF2 for notch-toughness-tested low-temperature service (ASTM International, 2026a), and A182 F11 or F22 for high-temperature service (ASTM International, 2026b). F304, F316 or F51 answers corrosive media. Sour service adds NACE MR0175 / ISO 15156 requirements.

An API trim number fixes the materials of a gate valve's stem, wedge face and seat face, and their hardness (Global Supply Line, 2023). For a forged steel gate valve with a carbon-steel or alloy-steel body, Bonney Forge's and Walworth's catalogs both offer Trim 8 and Trim 5 (Bonney Forge, n.d.; Walworth, n.d.).

The tenth edition of API 602 has its own trim clause, 6.1 "Trim Materials", and Table 12 "Nominal Seating Surfaces, Stem, or Weld-Deposited Materials and Hardness" (American Petroleum Institute, 2015). Global Supply Line's trim chart calls its data informational only and points to current API publications (Global Supply Line, 2023). A buyer confirms the trim against the edition ordered.

Global Supply Line's API 600/603/623/594/602 trim number chart lists Trims 8, 5, 12 and 16 (Global Supply Line, 2023); Wolseley Industrial's trim chart gives the same stem, wedge and seat materials (Wolseley Industrial, n.d.).

Bonney Forge's figure-number key pairs LF2 bodies with Trim 8, 5 or 12, and F11 with Trim 8 or 5 (Bonney Forge, n.d.). Walworth lists its A105 Trim 8 gate valve with seat A276-410+STL, wedge A276-420 and stem A276-410 (Walworth, n.d.). The Global Supply Line chart calls Trim 5 "Excellent for high pressure water and steam service" (Global Supply Line, 2023).

Trim 8 hardfaces the seat only; Trim 5 hardfaces both seating faces. Trims 12 and 16 move the stem and wedge to 316. A datasheet line reads "Trim 8: 13Cr stem and wedge, seat faced with CoCr alloy".

API Trim 8 means a 410 (13Cr) stem at 200 to 275 HB, a 410 (13Cr) wedge face at 250 HB minimum and a CoCr alloy (St Gr6) seat face at 350 HB minimum, per Global Supply Line's API trim chart (Global Supply Line, 2023). That chart calls it the "Standard trim for gate valves" (Global Supply Line, 2023).

Bonney Forge and Walworth pressure test their API 602 gate valves to API 598 (Bonney Forge, n.d.; Walworth, n.d.). API 622 (packing) and API 624 (rising-stem valve) are type tests: they qualify a design on a prototype, not each valve (Allen & Mertes, 2018). The datasheet names each standard, its edition and the test report required.

Bonney Forge's and Walworth's catalogs both state API 598 testing for their API 602 gate valves (Bonney Forge, n.d.; Walworth, n.d.). The tenth edition of API 602 has a Section 8.1, "Pressure Tests", and an Annex F, "Information to be Specified by the Purchaser" (American Petroleum Institute, 2015).

API 598's test table, as Wolseley Industrial reproduces it, lists shell, backseat, low-pressure closure and high-pressure closure tests, and requires the shell and backseat tests for gate valves of every size and class (Wolseley Industrial, n.d.). For a gate valve of NPS 4 and smaller in Class 1500 and below, which covers every API 602 size and class, the table makes the low-pressure closure test required and the high-pressure closure test optional, performed only when the purchase order specifies it (Wolseley Industrial, n.d.). The backseat test checks the seal between the stem's backseat shoulder and the bonnet.

Citing the EPA, Valve Magazine puts valves and connectors at over 90% of emissions from leaking equipment (Lowery, 2022). Issued in February 2014, API 624 tests with methane, and its packing must first qualify to API 622 (Lowery, 2022). API 624 covers rising and rising/rotating stem valves such as gate, globe and rising-stem ball valves (Allen & Mertes, 2018).

Valve World described the First Edition in 2018, while API 624 was being revised: 310 mechanical cycles with 3 thermal cycles from ambient to 260 °C (500 °F), 100 ppmv maximum and no packing adjustments (Allen & Mertes, 2018). API 624's scope includes body-bonnet leakage (Allen & Mertes, 2018). API 622 is a fixture test of the packing, with mechanical cycles, thermal cycles and corrosion tests (Allen & Mertes, 2018). Certification needs prototype testing, typically at an established third-party facility (Allen & Mertes, 2018). ISO 15848-1 covers type testing; ISO 15848-2 covers production testing (Allen & Mertes, 2018).

Note: API 622 and API 624 qualify a packing and a valve design, not each valve shipped. Ask for the type-test report that names the design and packing supplied, and write the edition on the purchase order.

For a rising-stem forged steel gate valve, API 624 is the emissions type test, run with methane on graphite packing that first qualified to API 622 (Lowery, 2022). Valve World described the 2014 First Edition as 310 mechanical and 3 thermal cycles to 260 °C (500 °F), with a 100 ppmv maximum and no packing adjustments (Allen & Mertes, 2018).

A quotation for a forged steel gate valve is only as exact as the datasheet lines sent with it.

• Service conditions: medium, H2S content, design pressure and temperature range, cyclic duty.
• Size: NPS with DN.
• API 602 configuration: edition (the eleventh is current), OS&Y or ISRS, standard or extended body, standard or full bore.
• Class rating: the Class 800 table of the API 602 edition in force, or ASME B16.34, at design temperature.
• End connection: ASME B16.11 socket weld, B1.20.1 NPT, B16.25 butt weld or B16.5 flanged (the tenth edition excludes flanged Class 800).
• Bonnet joint: bolted with gasket, welded, threaded and seal-welded, or union nut; pressure seal with design standard.
• Body and bonnet grade: A105, A105N, A350 LF2 with MDMT and impact test report, F11, F22, F304, F316, F51.
• Trim: API trim number with stem, wedge-face and seat-face materials.
• Test records: API 598, any optional closure test ordered, API 622 and API 624 type-test reports with editions.
• Sour service: NACE MR0175 / ISO 15156 or NACE MR0103 / ISO 17945 edition, hardness and heat-treatment records, bolting listed for the body grade (B7M with 2HM on A105).
• Socket-weld ends: the gap before welding, in the weld procedure.
• Material certificates: body, bonnet and trim.

A forged steel gate valve datasheet names the service, size, API 602 edition and configuration, class and rating basis, end connection and its standard, bonnet joint, body grade, trim number with its materials, test and type-test reports, and any sour-service records.

Price and delivery time change with body grade, class, end connection, extended body, trim hardfacing, bellows stem seal, emission type-test scope and sour-service documentation.

A request carrying these lines can be matched against Shinjo's gate valve range, the gate valves Shinjo supplies.

A forged valve has a pressure-containing body, and usually a bonnet, made from steel forgings such as ASTM A105, A350 LF2 or an A182 grade, not castings such as A216 WCB. Bonney Forge's catalog describes its API 602 gate valve body and bonnet as forged steel. API 602's tenth edition also lists castings, so datasheets say "forged" and name the grade.

A casting is poured into a mold; a forging is shaped from solid steel. Research on large steel ingots studies how forging closes voids left by casting. Emerson's ASME B16.34 bulletin prints the same Class 800 rating for cast WCB and forged A105: 136.2 bar (1975 psig) at -29 to 38 °C (-20 to 100 °F).

In API 602's tenth-edition scope, the two types are OS&Y (outside screw with rising stem), NPS 1/4 to 4 (DN 8 to 100), and ISRS (inside screw with rising stem), NPS 1/4 to 2 1/2 (DN 8 to 65) at Class 800 and below. Buyers confirm these limits against the eleventh edition in force.

The best gate valve for a line comes from whichever maker supplies documents that match the datasheet: the API 602 edition and configuration, the body grade, the trim number with its materials, API 598 test records, API 622 and API 624 type-test reports, and NACE MR0175 or MR0103 records where the service is sour.

No. API's product page for the tenth edition calls Class 800 "not a listed class designation" but an intermediate class widely used for socket-welding and threaded compact valves. WerMac describes API 602's Class 800 ratings as a linear interpolation between the ASME B16.34 Class 600 and Class 900 ratings, and the tenth edition prints its own Class 800 tables.

Emerson's ASME B16.34 bulletin prints these ratings for forged A105 and A350 LF2 at -29 to 38 °C (-20 to 100 °F): Class 600, 102.1 bar (1480 psig); Class 800, 136.2 bar (1975 psig); Class 1500, 255.3 bar (3705 psig). Above ambient, Class 800 uses the API 602 edition's table; Class 600 and 1500 use ASME B16.34.

Not under API 602's tenth edition, whose scope excludes flanged-end Class 800. It lists Class 800 with socket-welding or threaded ends at NPS 1/4 to 2 1/2 (DN 8 to 65), or with butt-welding ends at NPS 1/2 to 4 (DN 15 to 100). A buyer confirms both limits against the eleventh edition in force.

Per Global Supply Line's API trim chart, Trim 8 means a 410 (13Cr) stem at 200 to 275 HB, a 410 (13Cr) wedge face at 250 HB minimum and a seat face overlaid with CoCr alloy (the chart's St Gr6) at 350 HB minimum. That chart calls it the standard trim for gate valves. Trim 5 hardfaces both faces.

A socket-weld gate valve needs a gap of approximately 1.5 mm (1/16 in.) between the pipe end and the bottom of the socket before welding, as ASME B31.3 Figure 328.5.2C shows.

A forged steel gate valve is specified when the datasheet closes each decision. The API 602 configuration, checked against the edition in force, sets the size limit. The class needs its printed rating basis. Threaded and socket-weld ends carry ASME B31.3 cautions, and socket welds need the gap before welding. The bonnet and backseat, the body grade for the service and the trim number with its materials complete the valve.

The remaining decisions are records. API 598 sets the pressure tests the valves pass, while API 622 and API 624 type-test reports name the packing and design supplied, plus the edition. Where sour service applies, NACE MR0175 / ISO 15156, or MR0103 / ISO 17945 in a refinery, becomes a set of order requirements: the standard's edition, hardness and heat-treatment records, and the bolting. Class 800 is the intermediate class used for socket-weld and threaded valves. Above ambient, its rating comes from the Class 800 table of the API 602 edition in force. Any decision left open becomes the supplier's choice.

1. Allen, S., & Mertes, V. (2018, June). Testing to fugitive emissions standards: Which ones and why? Valve World. https://www.bray.com/docs/default-source/published-papers/emission-control-article.pdf
2. American Petroleum Institute. (2015). API Standard 602: Gate, globe, and check valves for sizes DN 100 (NPS 4) and smaller for the petroleum and natural gas industries (10th ed.) [Product description]. https://www.api.org/~/media/files/publications/whats%20new/602_e10%20pa.pdf
3. American Petroleum Institute. (2022). Gate, globe, and check valves for sizes DN 100 (NPS 4) and smaller for the petroleum and natural gas industries (API Standard 602, 11th ed.) [Catalog listing]. Accuris. https://store.accuristech.com/standards/api-std-602?product_id=2254605
4. American Society of Mechanical Engineers. (2018). Process piping: ASME code for pressure piping, B31 (ASME B31.3-2018). https://www.asme.org/codes-standards/find-codes-standards/b31-3-process-piping
5. ASTM International. (2026a). Standard specification for carbon and low-alloy steel forgings, requiring notch toughness testing for piping components (ASTM A350/A350M-26a). https://doi.org/10.1520/A0350_A0350M-26A
6. ASTM International. (2026b). Standard specification for forged or rolled alloy and stainless steel pipe flanges, forged fittings, and valves and parts for high-temperature service (ASTM A182/A182M-26a). https://doi.org/10.1520/A0182_A0182M-26A
7. Bonney Forge. (n.d.). Forged steel valves [Catalog]. https://bonneyforge.com/assets/files/FSV_compressed.pdf
8. Emerson. (2017). Pressure/temperature ratings ASME B16.34 valves (VCBUL-04493-EN) [Bulletin]. https://www.emerson.com/is/content/emerson/en/final-control/isolation-valves/bu-content/documents/ISV-BLT-Pressure-Temperature-Ratings-ASME-16.34-VCBUL-04493-EN.pdf
9. Global Supply Line. (2023). API 600/603/623/594/602 trim number chart: Standard trim configurations [Chart]. https://cdn.globalsupplyline.com.au/wpblob7acedbbe85/wp-content/uploads/2014/10/API600_VALVE_TRIM_CHART.pdf
10. Harris, N., Shahriari, D., & Jahazi, M. (2016). Analysis of void closure during open die forging process of large size steel ingots. Key Engineering Materials, 716, 579-585. https://doi.org/10.4028/www.scientific.net/kem.716.579
11. Lowery, T. (2022, October 10). Fugitive emissions standards for valves. Valve Magazine. https://valvemagazine.com/articles/fugitive-emissions-standards-for-valves/
12. SSM Alloys. (n.d.). NACE MR0175 / ISO 15156:2015 explained: Material requirements and selection guide for H2S environments. https://ssmalloys.com/nace-mr0175-iso-15156/
13. Walworth. (n.d.). API 602 gate, globe and check valves [Catalog]. https://walworth.com/multimedia/catalogos/us/API-602_EN_2017_1.pdf
14. WerMac. (n.d.). Valve pressure classes ASME B16.34. https://www.wermac.org/valves/valves_B16_34.html
15. Wolseley Industrial. (n.d.). Technical charts [PDF]. https://www.wolseleyindustrial.ca/wp-content/uploads/Wolseley-Industrial-Technical-Charts-Final.pdf

Last reviewed and updated: September 2026. Author: Shinjo Valve engineering team. For valve selection support or a quotation against your service conditions, contact our team.

A stainless steel butterfly valve is specified part by part: body, disc, stem and seat. A stainless disc in a ductile-iron body and an all-stainless valve are sold under the same name, so the datasheet lists each part. Stems are often 17-4 PH, chosen for strength. The seat usually sets the temperature limit: Bray rates peroxide-cured EPDM at -29 °C to 121 °C (-20 °F to 250 °F). A stainless body does not raise the pressure rating: ASME B16.34 rates a Class 150 CF8M body at 19.0 bar (275 psi) at -29 to 38 °C (-20 to 100 °F), just below WCB at 19.6 bar (285 psi). Name the design and API 609 category, the seat, the body style, the test standard and any sanitary framework on the datasheet.

A stainless steel butterfly valve is specified part by part; the phrase alone does not say which parts are stainless. On a datasheet it can mean a stainless disc and stem in a ductile-iron body, an iron valve with a stainless seat ring and shaft, or an all-stainless body, disc and stem. The buyer names each grade separately. Even an all-stainless valve is usually limited by its seat: Bray rates its peroxide-cured EPDM seat at -29 °C to 121 °C (-20 °F to 250 °F), far below the temperatures at which ASME B16.34 still rates a stainless body.

This guide is written for procurement and project engineers specifying an industrial or sanitary stainless butterfly valve against a service datasheet. On a compliant datasheet, CF8, CF8M and CF3M cover bodies and discs; the stem is often 17-4 PH; duplex serves seawater. Concentric, double-offset and triple-offset designs carry API 609 categories and ASME B16.34 ratings against WCB. The seat or liner sets the temperature limit. Sanitary class is set by 21 CFR 177.2600, 3-A, EHEDG and ASME BPE. Body style, ISO 5211, actuation, test standards, failure modes and a datasheet checklist are each specified separately.

• Specify each part separately. Body, disc, stem and seat each need their own material line.
• Stainless does not raise the rating. At ambient, ASME B16.34 rates a Class 150 CF8M body below WCB.
• The stem is often a different stainless. 17-4 PH is chosen for strength, 316 for corrosion resistance.
• The seat usually sets the temperature limit. An EPDM seat stops long before the body's printed rating does.
• Match the design to the duty. Concentric, double-offset or triple-offset, named with its API 609 category.
• Sanitary is a separate class. 316L, clamp or weld ends, and a seat compound complying with 21 CFR 177.2600.
• Design out the failure modes. Chloride pitting, disc-seat galling and liner permeation each need a datasheet line.

• TL;DR
• Abstract
• Key Takeaways
• By the Numbers
• Stainless Steel Butterfly Valve: Which Parts Are Actually Stainless
• Stainless Grades for the Body, Disc and Stem
• Concentric, Double-Offset and Triple-Offset Designs
• Seat and Liner Materials Set the Temperature Limit
• Sanitary Stainless Butterfly Valves: What 3-A, EHEDG, ASME BPE and FDA Require
• Body Style and Actuator Mounting for a Stainless Butterfly Valve
• Testing Standards to Name on the Purchase Order
• Failure Modes: Chloride Pitting, Galling and Liner Permeation
• Stainless Steel Butterfly Valve Datasheet Checklist
• Frequently Asked Questions
• Conclusion
• References

• 19.0 bar Class 150 CF8M/CF3M body rating at -29 to 38 °C, against WCB at 19.6 bar (Emerson Automation Solutions, n.d.-a)
• 121 °C upper limit of Bray's peroxide-cured EPDM seat (Bray International, n.d.-a)
• 816 °C upper limit of a triple-offset design in varying configurations (Anderson & Ferner, 2022)
• 200 ppm chloride threshold below which crevice corrosion should be rare for 304 (British Stainless Steel Association, n.d.)
• 1,000 ppm chloride threshold below which crevice corrosion should be rare for 316 (British Stainless Steel Association, n.d.)
• 10 bar the Watts ES-W7000 sanitary valve's rated pressure (Watts Water Technologies, n.d.)

A stainless steel butterfly valve is one whose datasheet names a stainless grade for one or more of its body, disc, stem and seat parts, and the phrase alone does not say which. Valve Magazine describes the basic configuration of most butterfly valves as a body, stem, disc, seat and stem seal (Anderson & Ferner, 2022).

Readers still choosing the valve type can start with the ball valve vs butterfly valve comparison.

Published data shows four common builds, each with a different set of stainless parts.

Bray's brochure B-1050 states that its seat design and internal disc-to-stem connection isolate the line media from the body and stem (Bray International, n.d.-a). On a lined, resilient-seated stainless butterfly valve, the fluid touches the seat and the disc; the body grade buys strength and external corrosion resistance, while the disc and seat decide internal corrosion life. In double- and triple-offset designs the seat sits in or on the body, so the body is wetted. The datasheet lists the wetted parts by grade.

Shinjo supplies butterfly valves; Shinjo's butterfly valve category page lists the current range, and the grade of each part still belongs on the datasheet.

On a butterfly valve datasheet, "stainless" can name the trim in an iron body or an all-stainless build. Body, disc, stem and seat are each specified by grade, drawing on options such as cast iron, ductile iron or 316 stainless bodies against 316 stainless or Hastelloy C-22 discs and stems (Bray International, n.d.-b).

Body and disc grade follow the medium, and the stem is chosen for strength first, because it carries the operating torque. A stainless steel butterfly valve pairs body and disc with the fluid, stem with seal and torque, and seat with the mating surface.

Emerson's reproduction of ASME B16.34 lists ASTM A351 CF8, CF3, CF8M and CF3M as cast valve materials (Emerson Automation Solutions, n.d.-a). In ASTM A351, CF8 and CF8M are the cast grades that correspond to 304 and 316, and CF3 and CF3M are their low-carbon versions. See the stainless steel grades comparison chart (ASTM, DIN, JIS, UNS) for cross-standard equivalents.

Per Val-Matic's Engineering Manual, "17-4 PH SS is similar to 304 SS except it is capable of being precipitation hardened (PH) using heat treatment, doubling its strength and making it a good choice for high performance valve trim. 17-4 PH withstands corrosive attack better than any of the 400 series stainless steels and in most conditions its corrosion resistance closely approaches that of 300 series stainless steel. 17-4 PH is primarily used as a stem material for high pressure butterfly and ball valves" (Val-Matic Valve and Manufacturing Corp., n.d.-a).

Val-Matic Bulletin 2000 lists shafts as ASTM A276 Type 304 or ASTM A564 Type 630, H1150 (Val-Matic Valve and Manufacturing Corp., n.d.-b). NIBCO's alloy table records 17-4PH as ASTM A 564 630, UNS S17400, so Type 630 is 17-4 PH (NIBCO, n.d.). NIBCO's figure-number key offers stems in 416SS, 17-4PH or 316SS (NIBCO, n.d.); 410 and 416 are martensitic 400-series grades (NIBCO, n.d.). Strength and wear resistance from 17-4 PH or 416; corrosion resistance from 316, matching the wetted 300-series parts. The heat-treatment condition goes on the datasheet.

A butterfly valve stem carries the operating torque, so strength drives the grade. Val-Matic reports precipitation hardening doubles 17-4 PH's strength and names it a primary stem material for high-pressure butterfly and ball valves (Val-Matic Valve and Manufacturing Corp., n.d.-a). The heat-treatment condition, such as H1150, goes on the datasheet (Val-Matic Valve and Manufacturing Corp., n.d.-b).

The British Stainless Steel Association (BSSA) writes that crevice corrosion should be rare below 200 ppm (mg/L) chloride for 304 types and below 1,000 ppm for 316 types, in waters (British Stainless Steel Association, n.d.). The Australian Stainless Steel Development Association (ASSDA) reports grade 316 offers a solution to around 90% of marine applications (Australian Stainless Steel Development Association, n.d.). The three most common marine duplex types are UNS S32304 (2304), UNS S31803 (2205) and UNS S32750 (2507) (Australian Stainless Steel Development Association, n.d.). S31803 has yield strength twice that of 304 or 316, with much higher resistance to pitting and crevice corrosion in seawater than 316 (Australian Stainless Steel Development Association, n.d.). Swagelok gives the pitting resistance equivalent number as PREN = %Cr + 3.3x(%Mo + %W) + 16x%N (Swagelok Company, n.d.). PREN ranks pitting resistance; it does not approve a grade for a service. Brine is chloride-bearing water above the BSSA threshold for 316, so duplex discs replace 316. See duplex stainless steel valves.

A stainless steel butterfly valve is offered in three industrial designs: concentric resilient-seated, double-offset high-performance and triple-offset metal-seated. The design decides the shutoff, the temperature envelope and whether the valve is rated by cold working pressure (CWP) or by ASME Class.

The API 609 monogram licensing form names two product classes, Category A and Category B (American Petroleum Institute, 2023). Category A covers valves rated by the manufacturer's CWP, usually of concentric design; Category B is ASME Class and pressure-temperature rated, with an offset seat and an eccentric or concentric disc (American Petroleum Institute, 2023). EN 593 is the European standard for general-purpose metallic butterfly valves. Bray names MSS SP-67 and API 609 Category A as its Series 20/21 design standards (Bray International, n.d.-b). The datasheet names the standard, category and edition; the buyer confirms it with the publisher.

Emerson's Vanessa Series 30,000 brochure lists Stellite grade 21 seats and a duplex resilient seal ring as a minimum, and says Stellite 21 coats the body seat (Emerson Automation Solutions, n.d.-b). The brochure's series range is -254 °C to 815 °C (-425 °F to 1500 °F) (Emerson Automation Solutions, n.d.-b). A series envelope is not the ordered configuration's envelope, so the datasheet names the configuration.

A history of the triple-offset butterfly valve is published by Shinjo. Shinjo supplies offset designs as well; Shinjo's flanged triple-eccentric butterfly valve page and Shinjo's metal-seated wafer butterfly valve page show two of them, and the category, class and seat still belong on the datasheet.

ASME B16.34 Class 150 working pressure, bar (psi), as printed in Emerson's reproduction of the tables (Emerson Automation Solutions, n.d.-a).

At -29 to 38 °C (-20 to 100 °F), Class 300 rates WCB 51.1 bar (740 psi) and CF8M/CF3M 49.6 bar (720 psi) (Emerson Automation Solutions, n.d.-a). ASME B16.34 places WCB in material group 1.1, CF8/CF3 in 2.1 and CF8M/CF3M in 2.2 (Emerson Automation Solutions, n.d.-a). The bulletin adds that its tables apply within the ASME standard, and a valve under the ASME Boiler and Pressure Vessel Code, the ASME code for pressure piping or government regulation is subject to that code's limits (Emerson Automation Solutions, n.d.-a).

A stainless body does not raise the class rating. At ambient it sits slightly below WCB, and the gap widens at 100 °C (212 °F). Category A is CWP-rated, so these tables govern a Class-rated body.

A stainless body does not lift the ASME B16.34 class rating. At -29 to 38 °C (-20 to 100 °F), a Class 150 CF8M/CF3M body rates 19.0 bar (275 psi) against WCB's 19.6 bar (285 psi); at 100 °C (212 °F) it rates 16.2 bar (235 psi) against 17.7 bar (257 psi) (Emerson Automation Solutions, n.d.-a).

A butterfly valve labeled ‘stainless’ still leaves the body, disc, stem and seat to specify one by one, each against the line’s chlorides, temperature and pressure class before a design or seat compound gets chosen. Shinjo’s butterfly valve category lists the current range across concentric, double-offset and triple-offset designs, wafer through double-flanged, for procurement teams working from a finished set of those grades.

In most stainless butterfly valves the seat or liner sets the temperature limit; the body's ASME B16.34 rating continues past it. A Class 150 CF8M/CF3M body rates 16.2 bar (235 psi) at 100 °C (212 °F) and 13.7 bar (199 psi) at 200 °C (392 °F) (Emerson Automation Solutions, n.d.-a), while Bray's BUNA-N reaches 100 °C (212 °F) and its peroxide-cured EPDM 121 °C (250 °F) (Bray International, n.d.-a).

Bray rates peroxide-cured EPDM from -29 °C to 121 °C (-20 °F to 250 °F) and FKM from -18 °C to 204 °C (0 °F to 400 °F) (Bray International, n.d.-a). Its Series 20/21 product page publishes -29 °C to 204 °C (-20 °F to 400 °F) as the valve's range, across EPDM, BUNA-N, PTFE-lined EPDM, FKM and polyurethane seats: the envelope, not the range of any one seat (Bray International, n.d.-b). Watts rates its EPDM-seated ES-W7000 sanitary valve at 10 bar (145 psi) from -20 °C to 135 °C (-4 °F to 275 °F), a second maker's EPDM at a different figure (Watts Water Technologies, n.d.). A range belongs to a compound and a datasheet, not to an elastomer name.

Bray rates PTFE-lined EPDM from -29 °C to 121 °C (-20 °F to 250 °F) and virgin PTFE from -18 °C to 204 °C (0 °F to 400 °F) (Bray International, n.d.-a). Val-Matic defines RPTFE as PTFE with a percentage of fiberglass or filler for strength, stability and resistance to abrasive wear, cold flow and permeation in molded seats (Val-Matic Valve and Manufacturing Corp., n.d.-a). Val-Matic gives RPTFE a range of -196 °C to 232 °C (-320 °F to 450 °F) (Val-Matic Valve and Manufacturing Corp., n.d.-a). Val-Matic cautions that RPTFE should not be used in applications that attack glass, such as hydrofluoric acid and hot or strong caustics (Val-Matic Valve and Manufacturing Corp., n.d.-a).

Valve Magazine gives a metal-seated double-offset valve a limit up to 482 °C (900 °F) in dirty service (Anderson & Ferner, 2022). Triple-offset designs span -196 °C to 816 °C (-320 °F to 1,500 °F) in varying configurations (Anderson & Ferner, 2022). An overview of valve seat and seat ring materials covers metal, resilient and PTFE families together.

Bray's peroxide-cured EPDM seat stops at 121 °C (250 °F) (Bray International, n.d.-a), while ASME B16.34 still rates a Class 150 CF8M/CF3M body at 13.7 bar (199 psi) at 200 °C (392 °F) (Emerson Automation Solutions, n.d.-a). The seat's published range, on the valve maker's datasheet, is the temperature line to specify, not the body's ASME rating.

Bray describes BUNA-N as a general purpose seat material particularly suitable for hydrocarbon service (Bray International, n.d.-a). Bray notes that FKM has improved acid, oil and temperature resistance over other seat materials (Bray International, n.d.-a). Val-Matic writes that EPDM has strong resistance to ozone, certain hydraulic fluids, brake fluids, steam and water (Val-Matic Valve and Manufacturing Corp., n.d.-a). NIBCO cautions against installing an EPDM liner in compressed air lines (NIBCO, n.d.). Val-Matic's Engineering Manual carries a chemical resistance guide that rates elastomers, plastics and metals chemical by chemical, and calls it a guide only (Val-Matic Valve and Manufacturing Corp., n.d.-a).

Work through three steps:

1. Name the medium, its concentration and the temperature range.
2. Check each wetted material (seat and disc, with stem if wetted) against the valve maker's chemical resistance guide.
3. Get the supplier's seat recommendation in writing. Bray notes that seat availability depends on valve size and series, and that the pressure and temperature of service also affect seat life and performance (Bray International, n.d.-a).

A sanitary stainless butterfly valve differs from an industrial one in its ends, its internal finish, its seat compound and its cleanable design, and a named framework or federal regulation sets each of those. The datasheet lists them one by one rather than calling the valve "food grade" without evidence.

Watts' Series W7000 two-piece sanitary butterfly valve uses a 316L stainless steel body and disc, an EPDM seat, and tri-clamp or tube-weld ends in NPS 1/2 to 4 (DN 15 to 100) (Watts Water Technologies, n.d.). It is rated 10 bar (145 psi) from -20 °C to 135 °C (-4 °F to 275 °F) (Watts Water Technologies, n.d.). Watts' datasheet lists a hygienic design compliant with 3-A standards, with end connections in accordance with the 3-A standard (Watts Water Technologies, n.d.), and prints "32 Ra internal surface finish" with no unit (Watts Water Technologies, n.d.). Because no unit is printed, the buyer asks for the unit and the measuring method rather than assuming one.

Rubber articles intended for repeated use may be safely used in producing, manufacturing, packing, processing, preparing, treating, packaging, transporting or holding food, subject to the provisions of the section (Code of Federal Regulations, n.d.). They are prepared from the natural and synthetic polymers and adjuvant substances the section lists, and that list includes acrylonitrile-butadiene copolymer, ethylene-propylene copolymer elastomers, chloroprene polymers, natural rubber and silicone elastomers (Code of Federal Regulations, n.d.). The food-contact surface, extracted with distilled water at reflux temperature (the boiling temperature of the extracting liquid), shall yield total extractives not to exceed 20 milligrams per square inch during the first 7 hours of extraction, nor 1 milligram per square inch during the succeeding 2 hours (Code of Federal Regulations, n.d.). For fatty food extracted with n-hexane at reflux, the limits are 175 milligrams per square inch during the first 7 hours and 4 milligrams per square inch during the succeeding 2 hours (Code of Federal Regulations, n.d.). Finished rubber articles are thoroughly cleansed before their first use in contact with food (Code of Federal Regulations, n.d.). Compliance belongs to the seat compound, not to the stainless body, so the datasheet names the compound and asks for the supplier's statement of compliance.

21 CFR 177.2600 permits rubber articles for repeated food contact if they are made from the polymers and adjuvants it lists, holds the food-contact surface to the aqueous and fatty extraction limits, and requires them to be cleansed before first use (Code of Federal Regulations, n.d.).

3-A Sanitary Standards, Inc. publishes sanitary design standards for dairy and food processing equipment. EHEDG, the European Hygienic Engineering and Design Group, publishes hygienic design guidelines and certifies cleanable design. ASME BPE is ASME's Bioprocessing Equipment standard for equipment in bioprocessing and pharmaceutical service. The purchase order names which framework applies and what evidence the supplier provides.

Note: A "food grade" seat in an industrial wafer body does not make a sanitary valve: the ends, the internal finish and a cleanable design belong to the sanitary class too.

Choose the body style from how the valve leaves the line and whether it must hold pressure at a dead end; then set the flange, face-to-face and top-flange standards. Flange drilling follows ASME B16.1, ASME B16.5 or EN 1092; face-to-face follows ISO 5752 (EN 558); actuator mounting follows ISO 5211.

Bray's Series 20/21 page lists ASME B16.1 Class 125, ASME B16.5 Class 150 and EN 1092 PN 10 (Bray International, n.d.-b). NIBCO's PDH course M180 rules out Class 250 cast iron and Class 300 steel flanges on its wafer and lug line, and forbids welding the pipe once the valve is bolted to the flanges (NIBCO, n.d.). Match the flange drilling to the pipe flanges.

Shinjo supplies wafer and lug valves: Shinjo's lug and wafer butterfly valve page, its lever-operated wafer butterfly valves and its high-pressure wafer butterfly valves are examples; confirm the flange drilling and dead-end rating on each datasheet.

Bray's brochure B-1050 rates a resilient-seated valve, metal disc and stem, at 10.3 bar (150 psi) bidirectional bubble-tight shutoff, NPS 1 to 20 (DN 25 to 500), with downstream flanges; without them, and with lug bodies and disc closed, that table drops to 5.2 bar (75 psi) at NPS 2 to 12 (DN 50 to 300) and 3.4 bar (50 psi) at NPS 14 to 20 (DN 350 to 500) (Bray International, n.d.-a). Watts' ES-W7000 by contrast rates its sanitary valve for dead-end service up to the valve's full pressure rating (Watts Water Technologies, n.d.). Ask for the dead-end rating in writing.

A wafer valve cannot serve dead-end; a lug valve can but may be de-rated (Val-Matic Valve and Manufacturing Corp., n.d.-a). Bray's brochure B-1050 rates its lug bodies at 5.2 bar (75 psi) at NPS 2 to 12 (DN 50 to 300) and 3.4 bar (50 psi) at NPS 14 to 20 (DN 350 to 500) dead-end, against 10.3 bar (150 psi) with downstream flanges (Bray International, n.d.-a). Get it in writing.

ISO 5211 is the ISO standard for part-turn actuator attachment to industrial valves. Bray's double-flanged Series 3A/3AH pairs ISO 5752 (EN 558) face-to-face with ISO 5211 mounting flanges, so one design serves many markets (Bray International, n.d.-b). A resilient-seated valve is position seated with continuous disc-to-seat interference; a triple-offset valve is torque-seated (Anderson & Ferner, 2022). For low-pressure 3.4 bar (50 psi) service, Bray's B-1050 uses a reduced disc diameter to lower seating torque and extend seat life (Bray International, n.d.-a). Val-Matic's Engineering Manual pairs traveling-nut actuators with the high seating torque of butterfly and ball valves (Val-Matic Valve and Manufacturing Corp., n.d.-a). Seat interference and torque seating shape the torque profile; size the actuator to the valve maker's published torque for the seat and service. Valve Magazine names manual (lever or wheel), electric, rack-and-pinion pneumatic and scotch yoke actuators (Anderson & Ferner, 2022). Resilient-seated stem sealing has a primary seal (seat flat to disc hub), a secondary seal (stem diameter larger than a hole in seat) and a tertiary upper stem seal (Anderson & Ferner, 2022). Shinjo's torque chart for triple-eccentric metal-seated butterfly valves shows the format such data takes.

The purchase order names one shell test and one seat test standard, the acceptance the seat test must meet, and the edition. A catalog's shutoff wording, such as "bubble-tight" or "zero leakage," is a claim, not an acceptance; it names no standard the tester can measure against.

A shell test pressurizes the assembled body to show it holds pressure; a seat or closure test pressurizes the closed disc against a stated acceptance. Four documents apply: API 598, "Valve Inspection and Testing"; ISO 5208, the pressure-testing standard for metallic industrial valves; EN 12266-1, the European standard for pressure tests on metallic industrial valves; and MSS SP-61, "Pressure Testing of Valves". Makers cite these standards. Bray's Series 20/21 lists MSS SP-61, API 598 and EN 12266-1 as its testing standards (Bray International, n.d.-b). Watts states that the W7000 is "inspected and tested in accordance with API 598" (Watts Water Technologies, n.d.). The purchase order names the standard and edition; the buyer confirms the current edition with the publisher.

A seat test proves that the closed disc seals to the acceptance the named standard and edition set, under that standard's test medium. A catalog word such as "bubble-tight" or "zero leakage" does not replace the standard and its acceptance.

Emerson's Vanessa Series 30,000 brochure prints a footnote: "Zero leakage means no visible leakage when tested at high pressure with water and low pressure with air according to existing international standards" (Emerson Automation Solutions, n.d.-b). Bray's Series 20/21 page gives a shutoff rating of "Bidirectional Bubble-tight" (Bray International, n.d.-b). A shutoff claim becomes a specification only when it names a test standard and an acceptance the tester can measure.

Note: Ask which standard, which test medium and which acceptance produced any "zero leakage" or "bubble-tight" line.

A stainless build does not prevent three failure modes in a butterfly valve: chloride pitting and crevice corrosion, galling where stainless slides on stainless, and permeation or cold flow of polymer seats. Each has a datasheet line that designs it out.

Per Swagelok, pitting begins with breakdown of stainless steel's protective chromium-rich oxide layer (Swagelok Company, n.d.). Crevice corrosion begins the same way but hides inside crevices (Swagelok Company, n.d.). The British Stainless Steel Association (BSSA) states crevice corrosion should be rare below 200 ppm (mg/L) chloride for 304 types, below 1,000 ppm for 316 types, in waters (British Stainless Steel Association, n.d.). BSSA states sodium hypochlorite, the main constituent of household bleach at around 5.25%, can cause pitting or crevice corrosion on most stainless steel grades (British Stainless Steel Association, n.d.). A butterfly valve has crevices under the seat or liner edge, at the disc-to-stem joint, at flange faces. Peer-reviewed research examines pitting of stainless steel in chloride and bromide solutions (Kaneko & Isaacs, 2000).

Val-Matic defines galling as the tearing of metal surfaces that rub together, from lack of lubrication or extreme contact pressure between materials of similar hardness (Val-Matic Valve and Manufacturing Corp., n.d.-a). NIBCO describes Stellite as very resistant to heat, abrasion, corrosion, impact, galling, oxidation, thermal shock and erosion (NIBCO, n.d.). Emerson's Vanessa triple-offset valve pairs a Stellite 21 body-seat overlay with a duplex seal ring (Emerson Automation Solutions, n.d.-b).

Galling tears metal surfaces that rub together, from lack of lubrication or extreme contact pressure between materials of similar hardness (Val-Matic Valve and Manufacturing Corp., n.d.-a). Stainless metal-seated butterfly valves answer it with dissimilar or hard-faced seating, such as a Stellite 21 overlay against a duplex seal ring (Emerson Automation Solutions, n.d.-b).

Val-Matic's Engineering Manual states that PTFE reinforced with fiberglass or filler resists cold flow and permeation in molded seats (Val-Matic Valve and Manufacturing Corp., n.d.-a). Bray describes its sintered PTFE as offering low permeability (Bray International, n.d.-a). Bray's conductive PTFE seat and disc have a minimum 3 mm (1/8 in) thickness against permeation, specific to that product (Bray International, n.d.-a). Bray's on/off velocity limits are 9 m/s (30 ft/s) for fluids and 54 m/s (175 ft/s) for gases, protecting the seat (Bray International, n.d.-a).

A quotation for a stainless steel butterfly valve is only as exact as the datasheet lines sent with it.

• Service line: medium, concentration, chlorides, solids, temperature, design pressure, throttling or on-off, flow direction, end-of-line.
• Size stated as NPS with DN.
• Rating basis as CWP, ASME Class or PN.
• Design standard: API 609 category, EN 593 or MSS SP-67.
• Body grade naming ASTM A351 CF8, CF8M or CF3M, or duplex; wetted or not.
• Disc grade and any coating or encapsulation.
• Stem grade with heat-treatment condition, for example ASTM A564 Type 630 H1150.
• Seat or liner compound with rated temperature range from the datasheet; metal seats give seal-ring materials and hardfacing.
• Body style, flange drilling, face-to-face standard, and the dead-end rating in writing.
• ISO 5211 top flange and operator (lever, gear, pneumatic or electric), actuator sized to the maker's published torque.
• Shell and seat test standard, acceptance and edition (API 598, ISO 5208 or EN 12266-1).
• Sanitary service: 316L wetted parts, clamp or weld ends, internal Ra with unit, seat complying with 21 CFR 177.2600, framework (3-A, EHEDG or ASME BPE) with evidence.
• Material certificates for each wetted part.

A stainless steel butterfly valve datasheet fixes the service, each wetted part's grade, the design with its API 609 category and rating basis, the seat's rated range, body style with dead-end rating, the top flange and actuator, and the test standard and acceptance. Sanitary orders name the framework.

Body, disc and stem grades move price and delivery. So do seat type (resilient, polymer or metal) and hardfacing, the design (concentric, double offset or triple offset), size and class, actuation, sanitary finish, and the test and documentation scope.

A request carrying these lines matches against Shinjo's butterfly valve range, so the reply names what Shinjo supplies for the specified service instead of asking the same questions back.

By construction, the valve is either stainless-trimmed (a stainless disc, stem or seat ring in an iron body) or all-stainless (body, disc and stem in stainless). By service class, it is industrial (wafer, lug or flanged; concentric or offset) or sanitary (316L, clamp or weld ends, and a seat compound complying with 21 CFR 177.2600).

Four appear across specifications. The seat sets the temperature limit: per Bray, peroxide-cured EPDM runs -29 °C to 121 °C (-20 °F to 250 °F). Resilient-seated valves are often rated by CWP, below ASME class ratings. A wafer body cannot serve dead-end. 304 or 316 parts can pit or crevice-corrode in chlorides.

No single figure applies. The seat is usually the part that wears, and per Bray, "the pressure and temperature of service also affect seat life and performance." In triple-offset valves, Valve Magazine notes that the seal ring can be laminated metal and graphite or a solid metal sheet, both field replaceable.

The best stainless steel butterfly valve for a given line is the one whose datasheet matches the service. Confirm the body, disc and stem grades against the medium; confirm the seat compound and its published temperature range; confirm the design category (concentric, double-offset or triple-offset); and confirm the test standard the purchase order names.

Only when it is built as a sanitary valve. That means 316L wetted parts, tri-clamp or tube-weld ends, a stated internal finish, a seat compound complying with 21 CFR 177.2600, and a named framework such as 3-A. An industrial wafer or lug valve with a 316 disc does not qualify.

Strength first. Per Val-Matic's Engineering Manual, 17-4 PH is precipitation hardened, "doubling its strength", and is "primarily used as a stem material for high pressure butterfly and ball valves." A 316 stem, by contrast, is chosen when the priority is corrosion resistance that matches the wetted parts.

When chloride exceeds what 316 can hold. Per BSSA, crevice corrosion should be rare below 1,000 ppm chloride in waters for 316 types. In seawater, ASSDA reports that 2205 has much higher resistance to pitting and crevice corrosion than 316; ASSDA lists 2304, 2205 and 2507 as the common marine duplex grades.

Per Bray, peroxide-cured EPDM runs -29 °C to 121 °C (-20 °F to 250 °F), and virgin PTFE runs -18 °C to 204 °C (0 °F to 400 °F). Per Val-Matic, RPTFE runs -196 °C to 232 °C (-320 °F to 450 °F). Read the rating on the valve maker's own datasheet; other makers publish different ranges.

It is sold under the same name, so the datasheet must list each part by grade. Per Bray, in a lined resilient-seated valve the seat isolates the body from the fluid; the disc and the seat then decide internal corrosion life, and the iron body sees no line media.

A stainless steel butterfly valve is specified when the datasheet closes every decision the phrase leaves open. Which parts of the valve are stainless, which parts touch the fluid, and the grade of each: body, disc, stem and seat named separately. The design and its rating basis: concentric, double-offset or triple-offset, rated to an ASME class or to a manufacturer's cold working pressure. The seat compound and the temperature limit it sets, with sanitary requirements added where the service asks for them. The body style, the flange drilling, the actuator interface and the stem sealing. The test standard and the acceptance the purchase order requires by name. And the lines that design out chloride pitting, disc-seat galling and liner permeation before the valve is built.

Where a resilient liner isolates the body from the flow, the disc, stem and seat carry the corrosion decision instead. Read together, those datasheet lines describe one valve.

1. Bray International. (n.d.-a). Resilient seated butterfly valves (Brochure B-1050). https://www.bray.com/docs/default-source/brochures/product-brochures/en_b-1050_rsb_valves_web.pdf
2. Bray International. (n.d.-b). Series 20/21 resilient seated butterfly valve. https://www.bray.com/valves-actuators-controls/butterfly-valves/resilient-seated/series-20-21-resilient-seated-butterfly-valve
3. Emerson Automation Solutions. (n.d.-a). Pressure/temperature ratings ASME B16.34 valves (Bulletin VCBUL-04493-EN). https://www.emerson.com/is/content/emerson/en/final-control/isolation-valves/bu-content/documents/ISV-BLT-Pressure-Temperature-Ratings-ASME-16.34-VCBUL-04493-EN.pdf
4. Val-Matic Valve and Manufacturing Corp. (n.d.-a). Engineering manual. https://www.valmatic.com/Portals/0/pdfs/EngineeringManual.pdf
5. Val-Matic Valve and Manufacturing Corp. (n.d.-b). Series 2000 AWWA butterfly valve (Bulletin 2000). https://www.valmatic.com/Portals/0/brochures/BFV_2000.pdf
6. NIBCO. (n.d.). Specifying and the technical evaluation of butterfly valves (PDH course M180). https://pdhonline.com/courses/m180/Nibco%20Butterfly%20Valve.pdf
7. Swagelok Company. (n.d.). Pitting corrosion vs. crevice corrosion: Identifying the differences. https://www.swagelok.com/en/blog/pitting-corrosion-crevice-corrosion-identifying-the-differences
8. Anderson, M., & Ferner, H. (2022, January 11). An overview of butterfly valves. Valve Magazine. https://valvemagazine.com/articles/an-overview-of-butterfly-valves
9. British Stainless Steel Association. (n.d.). Crevice corrosion. https://bssa.org.uk/bssa_articles/category-crevice-corrosion
10. Australian Stainless Steel Development Association. (n.d.). Corrosion resistance in marine environments. https://www.assda.asn.au/component/content/article?id=170
11. Code of Federal Regulations. (n.d.). Title 21, Chapter I, Part 177, Subpart C, Section 177.2600: Rubber articles intended for repeated use. https://www.ecfr.gov/current/title-21/chapter-I/subchapter-B/part-177/subpart-C/section-177.2600
12. Emerson Automation Solutions. (n.d.-b). Vanessa Series 30,000 triple offset valve: Basic configuration (Brochure) [PDF]. Askalon. https://www.askalon.com/uploads/downloads/brochure_series_30_000_basic_con.pdf
13. Watts Water Technologies. (n.d.). Series W7000 2-piece sanitary butterfly valves with tri-clamp and tube weld connections (ES-W7000). https://www.watts.com/dfsmedia/0533dbba17714b1ab581ab07a4cbb521/672249-source/639153956620000000/es-w7000-butterfly-valves.pdf
14. American Petroleum Institute. (2023). API Monogram Program licensing information form: API Standard 609, Butterfly valves (FM-3100-609). https://www.api.org/-/media/files/certification/monogram-apiqr/0_api-monogram-apiqr/lifs/api_609_licensing_information_form_20230821.pdf
15. Kaneko, M., & Isaacs, H. S. (2000). Pitting of stainless steel in bromide, chloride and bromide/chloride solutions. Corrosion Science, 42(1), 67-78. https://doi.org/10.1016/s0010-938x(99)00056-6

Last reviewed and updated: September 2026. Author: Shinjo Valve engineering team. For valve selection support or a quotation against your service conditions, contact our team.

A China butterfly valve can be a rubber-lined concentric wafer valve or an API 609 Category B triple-offset valve with a metal seat. Specify from the service conditions: design category, body style, design standard and edition, face-to-face and flange drilling, test standard with a named leakage acceptance, EN 10204 certificates and witnessed inspection. Compare suppliers only after the datasheets match.

China butterfly valve is a sourcing term, not a valve type. The phrase covers everything from a rubber-lined concentric wafer valve at one end to an API 609 Category B double-offset or triple-offset valve, the triple-offset with a metal seat, at the other. A vague line on a request for quotation (RFQ) lets both answer it. That spread, not the country on the nameplate, is the buyer's risk. The datasheet is where the buyer controls it: the design category, the body style, the standards, the tests and the certificates are decisions on paper before they are hardware.

This guide is written for an engineering, procurement and construction (EPC) buyer, a distributor procurement lead or a plant engineer turning a line list into a purchase order with a Chinese supplier. Decisions come in order: service conditions, then design category and body style, with ISO 5211 setting the actuator top flange. Design standards a Chinese supplier builds to are API 609, EN 593, MSS SP-67 and SP-68, AWWA C504 and GB/T 12238. Shell and seat tests follow API 598, ISO 5208, EN 12266-1 and GB/T 13927. Certificate levels track EN 10204. Suppliers are judged on operations and third-party inspection, and known defects map back to spec lines and an RFQ checklist.

• The spread is the risk, not the origin. One vague RFQ line can draw very different valves.
• Start from service conditions. Media, pressure class, temperature, shutoff and end-of-line duty set design and body style.
• Name the design standard and edition. API 609 Category A or B, EN 593, AWWA C504 or GB/T 12238.
• Put the test and leakage rate on the PO. API 598, ISO 5208, EN 12266-1 or GB/T 13927.
• Ask for EN 10204 3.1 certificates with heat numbers. Then verify pressure-retaining parts by positive material identification (PMI) and measurement.
• Judge a supplier by evidence. Who casts and machines, what it tests in-house, and what it documents.
• Ask for the supplier's TS license copy and scope. Back it with third-party inspection of your own valves.

• TL;DR
• Abstract
• Key Takeaways
• China Butterfly Valve: One Search Term, Very Different Valves
• How to Choose: Service Conditions, Design Category, Body Style
• Butterfly Valve Standards: API 609, EN 593, MSS SP-67, AWWA C504, GB/T 12238
• Butterfly Valve Inspection and Testing: API 598, ISO 5208, EN 12266-1, GB/T 13927
• Specification Setups by Service Condition
• Materials and Certificates: What to Verify, Part by Part
• How to Judge a Chinese Butterfly Valve Supplier
• Known Defects, and the Catalog Words to Ignore
• Butterfly Valve RFQ Checklist: What the Datasheet Must Say
• Frequently Asked Questions
• Conclusion
• References

China butterfly valve is a sourcing term, not a valve type. The term covers a wide range: a concentric, rubber-lined wafer valve at one end, an API 609 Category B triple-offset valve with a metal seat at the other. The datasheet, not the origin, decides which one arrives.

Solliec and Danbon list three advantages of butterfly valves: their low cost, their mechanical suitability for fast operation, and their small pressure drops when they are fully open (Solliec & Danbon, 1999).

Where the valve type itself is still open, the gate valve vs ball valve comparison and the ball valve vs butterfly valve breakdown cover that question. The remaining risk lives inside butterfly designs. Two quotes for "butterfly valve, NPS 8 (DN 200), Class 150" can describe different designs, seats and tests, so comparing their prices means nothing until the datasheets match. The buyer controls the result through the datasheet, not the country of origin.

Catalogs often write "eccentric" where API 609 datasheets write "offset", and the buyer confirms the geometry on the drawing, not by the name.

• Concentric: stem through the disc center, disc centered in the bore, edge seals against a resilient seat.
• Double offset (double eccentric, high-performance): stem behind the sealing face; disc lifts clear of the seat soon after it starts to open.
• Triple offset (triple eccentric): adds an angular offset so a metal seal ring meets a metal seat without rubbing.
• Resilient-seated (soft-seated, rubber-lined): describes the seat material, not the disc geometry.
• Metal-seated: describes the seat, used on triple-offset and some double-offset designs.

The sourcing risk on any butterfly valve line to China is the design spread, not the country of origin. One line can draw a concentric wafer valve or an API 609 Category B triple-offset valve with a metal seat. When the datasheet pins design, seat and tests, the country stops deciding what arrives.

Choose a butterfly valve by working from the service conditions to the design category, then to the body style and top flange, and write each choice on the datasheet. Pressure, temperature, medium and duty come first. They fix the category. The seat follows the category, and the body style follows the piping.

Answer each line before you touch a catalog:

• Medium in the line, and any solids or particulates carried.
• Pressure class or PN, and maximum differential across the closed disc.
• Minimum and maximum service temperature, in °C and °F.
• Shutoff tightness the service needs (it becomes the test acceptance).
• On-off or throttling duty, and how often the valve cycles.
• Flow direction: one-way, or bidirectional through the disc.
• End-of-line service, yes or no, and its dead-end rating.

Cavitation behind a partly open disc is a studied risk when a butterfly valve throttles near closed (Brett et al., 2011).

The three API 609 designs differ in how the disc and seat meet (American Petroleum Institute, 2026).

API 609 defines two categories. Category A covers butterfly valves rated by the manufacturer's cold working pressure, usually of concentric design (American Petroleum Institute, 2026). Category B covers ASME Class and pressure-temperature rated butterfly valves with an offset seat and an eccentric or concentric disc (American Petroleum Institute, 2026). For reference, Shinjo supplies a double eccentric butterfly valve; confirm its category and rating on the datasheet like any other.

Match the design to a body style. A wafer valve clamps between two pipe flanges by bolts that pass outside the body, and is not for end-of-line service. A lug valve has threaded lugs that let each pipe flange bolt to the valve separately, so the downstream side can be removed for end-of-line service only within the dead-end rating the supplier states in writing. A double-flanged valve carries its own two flanges. A butt-weld valve is welded into the line, has no flange joint, and removal means cutting.

Name the ISO 5211 top flange and drive on the datasheet (International Organization for Standardization, 2017). Ask the supplier for seating, unseating and dynamic torque data. Solliec and Danbon note that "the fluid dynamic torque about the axis of large valves has to be considered as the actuator could be overstrained" (Solliec & Danbon, 1999). A torque chart for triple-eccentric metal-seated butterfly valves shows the format; ask for numbers that match your valve.

Choose a butterfly valve in three moves and write each choice on the datasheet. First list the service conditions. Second pick the design category (concentric, double offset or triple offset) from those conditions (American Petroleum Institute, 2026). Third pick the body style (wafer, lug, double-flanged or butt-weld) from the piping and end-of-line rules.

A butterfly valve datasheet names one design standard, the interface standards that fit the valve to the pipe and actuator, and the edition of each.

The design standard sets construction and rating basis. Interface standards then fit the valve to its pipe and its actuator.

AWWA C504 covers rubber-seated butterfly valves 3 in. (75 mm) through 72 in. (1,800 mm) in diameter, for raw water, potable water, wastewater and reclaimed water with pH 6-12 and a temperature of 0.6-52 °C (33-125 °F) (American Water Works Association, n.d.). The Manufacturers Standardization Society of the Valve and Fittings Industry (MSS), an ANSI-accredited standards developer, maintains MSS SP-67 (Butterfly Valves) and MSS SP-68 (High Pressure Butterfly Valves with Offset Design) (Manufacturers Standardization Society, 2011). When a supplier lists API 609 and GB/T 12238 together, ask which one governs design and which governs dimensions.

Face-to-face dimensions are set by ISO 5752 or EN 558; ISO 5752:2021 is the ISO edition (International Organization for Standardization, 2021). Flange drilling comes from ASME B16.5 for smaller sizes, ASME B16.47 for larger sizes, or EN 1092-1 for PN-designated steel flanges. For a Class-rated valve, read the pressure-temperature rating from the ASME B16.34 table for the named material group and class; never interpolate between printed values, and never take the rating from a catalog (American Petroleum Institute, 2026). Top-flange dimensions for the part-turn actuator come from ISO 5211 (International Organization for Standardization, 2017).

Editions change. ISO 5752:2021, the third edition (June 2021), sets face-to-face dimensions for metal valves used in flanged pipe systems (International Organization for Standardization, 2021). For API 609, MSS SP-67, SP-68, EN 593, AWWA C504 and GB/T 12238, write the edition into the purchase order and confirm it with the publisher (api.org, msshq.org, awwa.org, openstd.samr.gov.cn). A bare standard number is not enough.

The revised AWWA C504 added foreword guidance on chlorine and chloramine degradation of elastomers (American Water Works Association, n.d.). That guidance is a pointer for the buyer's own material check, not a verdict about any elastomer.

A Chinese butterfly valve datasheet is complete when it names one design standard (API 609, EN 593, MSS SP-67 or SP-68, AWWA C504, GB/T 12238), the interface standards that fit the valve to the pipe (face-to-face, flange drilling, pressure-temperature rating) and to the actuator (top flange), and the edition of each standard.

Two pressure tests decide whether a butterfly valve leaves the works. The shell test proves the body holds pressure without visible leakage. The seat test proves the closed disc seals to an acceptance the purchase order names. State the test standard and the acceptance on the datasheet, not a catalog phrase.

The shell test pressurizes the assembled body with the disc part open and looks for weeps at the flanges, the stem seal and the body joint. API 598 requires no visible leakage for the shell test (Wermac, 2025). The seat test pressurizes one side of the closed disc and measures what passes through to the other. The acceptance is what the purchase order names, not what the valve builder assumes. On a bidirectional valve, the seat test is run from each direction.

The API 598 bands are smaller than NPS 2 (DN 50), NPS 2 to 6 (DN 50 to 150), NPS 8 to 12 (DN 200 to 300), and larger than NPS 12 (DN 300) (Wermac, 2025).

A metal-seated triple-offset valve is ordered to a named API 598 metal-seat acceptance, or to a named ISO 5208 or EN 12266-1 rate, and the test report must show that acceptance. A catalog line like "zero leakage" or "bubble-tight" is not an acceptance until it names a test standard and a rate.

Note: API 598 does not use Classes I to VI. Those classes come from ANSI/FCI 70-2, the control-valve seat leakage standard (Wermac, 2025). If a quote for an on-off butterfly valve says "Class VI", ask which standard and which test produced it.

Witness the shell test, the seat test from each direction on a bidirectional valve, the operation and torque check through a full cycle, the dimensional check against the approved drawing, and the marking and serial numbers. The test report should state the standard, the test medium, the test pressure, the duration, the result and the valve serial number. A third-party witnessed test supports an EN 10204 3.2 certificate.

Four valve test standards state seat leakage differently. API 598, whose scope includes butterfly valves, sets seat acceptance by four NPS size bands and by resilient-seated versus metal-seated construction, while ISO 5208 and EN 12266-1 use lettered rates the purchaser names (Wermac, 2025). GB/T 13927 is China's national pressure-test standard for industrial metallic valves (Standardization Administration of China, 2022).

A datasheet that names the design category, body style, seat material and test acceptance is what a supplier needs to price a line correctly. Shinjo supplies a range of butterfly valves, from concentric to triple offset, and quotes each design against the service conditions you send rather than a generic catalog listing.

There is no best China butterfly valve, only a setup that matches the service. Each setup names a design category, a body style, a governing standard and a test set, chosen before any product page opens.

AWWA C504 covers rubber-seated butterfly valves 3 in. (75 mm) through 72 in. (1,800 mm) in diameter, for raw water, potable water, wastewater and reclaimed water with pH 6-12 and a temperature of 0.6-52 °C (33-125 °F) (American Water Works Association, n.d.). Name the seat elastomer on the datasheet, and ask the supplier for the basis of its resistance to the disinfectant. The revised AWWA C504 adds foreword guidance on chlorine and chloramine degradation of elastomers (American Water Works Association, n.d.). State no verdict on any compound.

HVAC and chilled water take a concentric resilient-seated valve. Choose wafer for in-line service between two pipe flanges. Choose lug where end-of-line isolation is called for, and only within a dead-end rating the supplier states in writing. A wafer clamps between flanges by bolts that pass outside the body and is not for end-of-line service. Lug threads let each flange bolt to the valve separately. Where an actuator is fitted, the ISO 5211 top flange sets the mounting. That design range covers Shinjo's lug and wafer butterfly valves.

Steam and hot hydrocarbons take an offset metal-seated design: a triple offset, or a double offset with a metal seat. The category is API 609 Category B, which sets a pressure-temperature rating by ASME B16.34 Class for the material group; read the rating from the table, never interpolated (American Petroleum Institute, 2026). A fire-type test belongs on the purchase order only when the service specification calls for one; the purchaser names the standard and asks for the type-test report for that valve family and size. Shinjo supplies triple-offset butterfly valves in PN 63 and PN 100 ratings. For ASME Class 150, 300 and 600 service, Shinjo also supplies ANSI-flanged metal-seat butterfly valves.

Seawater and brine start with the pressure and temperature step, then turn on the materials. Check every wetted part, and the lining or coating with its thickness, against a compatibility source: the polymer supplier's datasheet, an alloy compatibility chart, and NACE/AMPP MR0175 (ISO 15156) where the service is sour. Verify each material by measurement and by PMI on the part before it ships. The material verdict comes from the datasheet, the mill certificate and the PMI report.

Slurry and abrasive media are usually handled by a resilient-lined design. State the liner material on the drawing, and its thickness against the approved drawing. Both belong on the datasheet and on the inspection report. State whether the valve throttles or only isolates: throttling wear on the disc edge and seat is not the same duty as on-off cycling. Ask the supplier for a service reference in the same medium at a similar particle load and flow, and record that reference on the RFQ line.

A China butterfly valve setup names a design category, body style, governing standard and test set, chosen from the service. Waterworks selection rests on the AWWA C504 rubber-seated scope (American Water Works Association, n.d.). Hot service is set by API 609 Category B and ASME B16.34 class ratings (American Petroleum Institute, 2026). Materials are checked, not assumed.

Once the setup is written down, Shinjo's butterfly valve category page is where to match it against the designs Shinjo supplies.

Material risk is controlled by documents that match the part, and by checks on the part itself. Ask for the grade the datasheet names, confirm the heat number, and read the alloy on the casting before shipment.

EN 10204 defines four inspection documents. Type 2.1 is a declaration of compliance with the order, without test results (European Committee for Standardization, 2004). Type 2.2 is a test report on non-specific inspection (European Committee for Standardization, 2004).

An EN 10204 3.1 inspection certificate carries specific test results validated by the manufacturer's authorized inspection representative, independent of manufacturing; it proves the results are the part's own (European Committee for Standardization, 2004). Type 3.2 adds a second signature: the purchaser's authorized representative, or an inspector named in official regulations (European Committee for Standardization, 2004).

Ask for 3.1 on pressure-retaining parts, and 3.2 where the project requires a third-party or purchaser witness. Traceability rests on the heat number stamped or cast on the part matching the certificate; positive material identification reads the alloy composition on the part itself (European Committee for Standardization, 2004).

The compatibility verdict for any material and medium rests on three sources. First, the elastomer or polymer supplier's datasheet, which states each compound's temperature limits and known incompatible media. Second, NACE/AMPP MR0175 (ISO 15156) for sour service; it governs metallic materials in oil and gas environments containing hydrogen sulfide (International Organization for Standardization, 2015). Third, the supplier's own compatibility chart, which pairs each seat or liner with rated media. Laminated metal seats are one seat construction used in triple-offset valves (Kwak et al., 2019). The approved drawing carries each hardness value, chemistry limit and thickness figure.

Judge a China butterfly valve supplier by what it can show, not by a ranking or logo wall. No 'top manufacturers' list can tell a buyer whether one supplier's valve fits one line; the answer sits in drawings, test records and certificates.

Ask which operations happen in-house: casting, machining, assembly and testing. A supplier that pours its own bodies answers for the metallurgy on site. A machine shop that buys castings and does its own machining is common and workable. A trader can be a sound supplier if it holds the approved drawings, material certificates and test records, and names the factory that answers for the casting.

A supplier can only test what its bench covers. The bench should carry the largest size and class on the order, with calibrated gauges whose certificates are on file. Ask for a sample test report on a valve of the same family, a dimensioned drawing at the size ordered, and a material certificate template. An outside laboratory's report should carry a China National Accreditation Service for Conformity Assessment (CNAS) accreditation number that resolves at cnas.org.cn.

Place a sample or first-article order before volume. A third-party inspector, for example SGS, Bureau Veritas, TUV or Intertek, witnesses the shell and seat tests and checks dimensions against the approved drawing. A witnessed test supports an EN 10204 3.2 certificate on the production order.

The Special Equipment Safety Law of the People's Republic of China was promulgated on June 29, 2013, by the Standing Committee of the National People's Congress, and came into force on January 1, 2014. It defines special equipment as boilers, pressure vessels (including gas cylinders), pressure pipelines, elevators, lifting machinery, passenger ropeways, large-scale amusement devices and non-road motor vehicles (Standing Committee of the National People's Congress, 2013). The State runs a category-based license system on the production of special equipment, and imported special equipment must comply with the safety technical specifications that apply in China (Standing Committee of the National People's Congress, 2013). The list names pressure pipelines but not valves; whether a general-service butterfly valve falls under the license could not be confirmed from open sources. Ask which license the supplier holds, for which product scope, see the copy, and rely on third-party inspection either way.

Ask for and read the following evidence before signing the order:

• In-house operations named on paper.
• Test bench range covering the ordered size and class.
• A sample test report from the same valve family.
• The dimensioned drawing, marked approved.
• A material certificate sample with heat numbers.
• License copy and product scope, wherever a license is claimed.
• Third-party inspection access.

A China butterfly valve supplier is judged by evidence the buyer can verify: a CNAS accreditation number that resolves at cnas.org.cn, a signed test report with heat numbers, a drawing stamped as approved, and a third-party witnessed test on the valves shipped, which supports an EN 10204 3.2 certificate. A logo wall proves none of these.

The defects that matter are the ones a datasheet and an inspection can catch. Ayman Cheta of Shell Global Solutions has listed valves among industrial items commonly counterfeited, as reported by Valve Magazine (Cleaveland, 2009). In the control-valve field, refurbished units resold by questionable suppliers are "just as big a problem as newly made pieces" (Cleaveland, 2009). The US Nuclear Regulatory Commission uses the term Suspect/Counterfeit Items (S/CI), and the Department of Energy requires contractors to report every finding (Cleaveland, 2009). Each defect worth watching is a specification risk the buyer controls.

Note: When two quotes for the same line differ widely, compare the datasheets line by line before comparing prices. A price gap has to come from something the drawing or the test plan will show.

• "zero leakage" or "bubble-tight": ask for a named test standard and the rate
• "API standard" or "international standards": ask for a number, an edition and the API 609 category
• "high performance": ask for the design category and Class rating
• "fire-safe design": ask for a type-test report for that valve family
• "heavy duty", "premium" or "OEM quality": ask for the datasheet lines these words replace
• certificate logos: ask for a certificate number and product scope
• "100% tested": ask which tests, on which sample, with what acceptance

A datasheet line specifies; an adjective does not. Valve Magazine's reporting names valves among the industrial items commonly counterfeited (Cleaveland, 2009). The words that carry specification weight are a standard number and edition, an API 609 category, a Class or PN rating, and a named test with a stated acceptance.

A quotation is only as exact as the service conditions and datasheet lines sent with it.

• Tag and quantity for the line.
• Size as NPS with the DN equivalent.
• Body style and end connection, with flange standard and drilling.
• Face-to-face standard the valve is built to.
• Pressure class or PN for the body.
• Design standard, edition and API 609 category where it applies.
• ASME B16.34 material group for a Class-rated valve.
• Medium and solids carried by the line.
• Temperature and pressure ranges: minimum, maximum, operating, differential.
• Flow direction and end-of-line duty, stated clearly.
• Design category: concentric, double offset or triple offset.
• Body, disc, stem, seat or liner and coating materials.
• Operator package: type, ISO 5211 flange, torque, fail position.
• Test standard, acceptance rate and which tests are witnessed.
• EN 10204 certificate type per part.
• Marking and traceability stated on the valve.
• Documents required: drawing, test reports, certificates.
• Third-party inspection and its scope.

Four line conditions block a firm quotation:

• Differential pressure is unknown.
• Medium composition is unknown.
• End-of-line duty is undecided.
• Standard edition is not named.

Price and delivery time move with the design category, the materials selected, the level of witness and documentation required, the size and class of the valve, and the operator package.

An RFQ that lets a supplier price a China butterfly valve carries the tag and quantity, size in NPS with DN, body style and end connection, pressure class or PN, design standard and edition, service conditions, design category, materials by part, operator with ISO 5211 flange and torque, test standard, EN 10204 certificate type and required documents.

A request that carries these lines can be matched against Shinjo's butterfly valve range, and the Shinjo product catalog is the reference used to check what Shinjo supplies against each row.

API 609 defines two types. Category A covers butterfly valves rated by the manufacturer's cold working pressure, usually of concentric design. Category B covers ASME Class and pressure-temperature rated butterfly valves with an offset seat and an eccentric or concentric disc. By geometry, the split is concentric versus offset.

A butterfly valve is a quarter-turn valve that isolates or regulates flow by turning a disc across the bore. Solliec and Danbon list three advantages: low cost, fast operation and a small pressure drop when fully open. The disc stays in the flow, so throttling range is limited.

The "top ten" lists that rank highly on search are published by vendors themselves. Judge any supplier by in-house operations, test capability, the documents it can hand you, and third-party inspection at the factory, not by its position on such a list.

No brand is best for every service. The right valve is the one whose datasheet matches the service: the API 609 design category, the design standard and its edition, the shell and seat test acceptance, and the material and inspection certificates the purchase order requires.

That depends on end-of-line duty. A wafer body is clamped between two pipe flanges by bolts that pass outside the body, and is not for end-of-line service. A lug body lets each pipe flange bolt to the valve separately and allows end-of-line service within the dead-end rating the supplier states in writing.

All three set shell and seat tests for valves. API 598 writes seat acceptance by size band and seat type. ISO 5208 and EN 12266-1 write it as lettered rates the purchaser names on the order. Name one standard and its acceptance on the PO.

Both are inspection certificates with specific test results. A 3.1 certificate is validated by the manufacturer's authorized inspection representative, independent of manufacturing. A 3.2 certificate is validated both by that representative and by the purchaser's authorized representative or an inspector named in official regulations.

That could not be confirmed from open sources. The Special Equipment Safety Law's list names boilers, pressure vessels, pressure pipelines, elevators and several other categories, but not valves as such. Ask the supplier for a copy of the license and its product scope, and rely on third-party inspection either way.

A China butterfly valve arrives right when the order closes the spread between a single catalog term and many different designs. The order of the datasheet is the same on every line. Service conditions come first: medium, temperature range, pressure rating, cycle rate and end connections. From those duties follow the design category and the body style, in that direction, never the reverse. The design standard and its edition go on the datasheet next, character for character, so the supplier and the inspector read the same rules.

Test standard and acceptance follow, with the leakage rate the purchaser names rather than a vendor default. Certificates tie the material back to the parts. Supplier evidence, in-house scope, test capability and license copies where they apply, together with a witnessed inspection at the factory, turn the paper contract into a valve on the pipe.

1. Solliec, C., & Danbon, F. (1999). Aerodynamic torque acting on a butterfly valve. Comparison and choice of a torque coefficient. Journal of Fluids Engineering, 121(4), 914-917. https://doi.org/10.1115/1.2823555
2. Brett, G., Riveland, M., Jensen, T. C., & Heindel, T. J. (2011). Cavitation from a butterfly valve: Comparing 3D simulations to 3D X-ray computed tomography flow visualization. In ASME-JSME-KSME 2011 Joint Fluids Engineering Conference: Volume 2, Fora (pp. 161-169). ASMEDC. https://doi.org/10.1115/ajk2011-33003
3. Kwak, H., Seong, H., & Kim, C. (2019). Design of laminated seal in cryogenic triple-offset butterfly valve used in LNG marine engine. International Journal of Precision Engineering and Manufacturing, 20(2), 243-253. https://doi.org/10.1007/s12541-019-00056-6
4. American Petroleum Institute. (2026). API Standard 609: Butterfly valves: Double-flanged, lug- and wafer-type, and butt-welding ends (10th ed.). https://www.api.org/-/media/Files/Certification/Monogram-APIQR/0_API-Monogram-APIQR/Advisories-Updates/Updates/API_Standard_609_10th_Edition_Update_20260526.pdf
5. American Water Works Association. (n.d.). AWWA's comment period on ANSI/AWWA C504 - Rubber-seated butterfly valves. Retrieved September 28, 2026, from https://www.awwa.org/AWWA-Articles/awwas-comment-period-on-ansiawwa-c504-rubber-seated-butterfly-valves
6. Manufacturers Standardization Society. (2011, December 20). MSS publishes eleven revised standards [Press release]. https://msshq.org/news/587140/MSS-PUBLISHES-ELEVEN-REVISED-STANDARDS.htm
7. International Organization for Standardization. (2021). ISO 5752:2021 - Metal valves for use in flanged pipe systems - Face-to-face and centre-to-face dimensions (3rd ed.). https://www.iso.org/standard/77335.html
8. International Organization for Standardization. (2017). ISO 5211:2017 - Industrial valves - Part-turn actuator attachments. https://www.iso.org/standard/62594.html
9. Wermac. (2025, October). Leakage of valves - Testing API 598, ANSI FCI 70-2, MSS-SP-61 and ISO standard 5208. Retrieved September 28, 2026, from https://www.wermac.org/valves/valve_leakage.html
10. Standardization Administration of China. (2008). GB/T 12238-2008 - Flanged and wafer resilient seal butterfly valves. https://openstd.samr.gov.cn/bzgk/std/newGbInfo?hcno=EF682E1459A71302420FFA623452BB51
11. Standardization Administration of China. (2022). GB/T 13927-2022 - Industrial valves - Pressure testing. https://openstd.samr.gov.cn/bzgk/std/newGbInfo?hcno=67B6DC8CAE15EFF6FD97717C3AF58EE2
12. European Committee for Standardization. (2004). EN 10204:2004 - Metallic products - Types of inspection documents. https://standards.iteh.ai/catalog/standards/sist/aba75e3c-8a86-4a55-aa11-9fa7c3feebbf/sist-en-10204-2004
13. International Organization for Standardization. (2015). ISO 15156-1:2015 - Petroleum and natural gas industries - Materials for use in H2S-containing environments in oil and gas production - Part 1: General principles for selection of cracking-resistant materials. https://www.iso.org/standard/66640.html
14. Standing Committee of the National People's Congress. (2013). Special equipment safety law of the People's Republic of China [English translation, China Justice Observer]. Retrieved September 28, 2026, from https://www.chinajusticeobserver.com/law/x/special-equipment-safety-law-20130629
15. Cleaveland, P. (2009, July 17). Suspicious and counterfeit valves: An avoidable danger. Valve Magazine. https://valvemagazine.com/articles/suspicious-and-counterfeit-valves-an-avoidable-danger

Last reviewed and updated: September 2026. Author: Shinjo Valve engineering team. For valve selection support or a quotation against your service conditions, contact our team.

A ball valve seals by rotating a bored sphere a quarter turn against two seats. Specify it by more than size and class: floating or trunnion support, full, reduced or V-port bore, body construction, seat material against the maximum temperature at operating pressure, the governing standard (API 6D for pipelines, API 608 or ISO 17292 for process piping, ASME B16.34 for pressure-temperature ratings), the fire, emission and isolation tests, and actuator torque with margin.

A ball valve is a quarter-turn rotary valve that isolates flow by rotating a bored sphere against two seats, and two ball valves with the same size and pressure class can perform very differently in the same line. The words that decide service life sit further down the datasheet: floating or trunnion-mounted support, full, reduced or V-port bore, body construction, seat material and its temperature limit at operating pressure, the governing design standard, the fire, emission and isolation tests the valve has passed, and the actuator's torque margin. Size and pressure class are where the specification starts, not where it ends.

Readers in view are procurement and project engineers specifying against a line list. Sealing is created by line pressure: a floating ball rides onto the downstream seat; a trunnion-mounted ball is held on upper and lower trunnions while spring-loaded seats push upstream. Size and pressure class together decide the crossover. Bore (full, reduced or V-port) changes flow, pigging and modulating capability; body construction from one-piece to fully welded decides whether repair is possible in the line. Virgin PTFE, RPTFE and PEEK seats derate as pressure rises; metal seats serve above the polymer range. DBB, DIB-1 and DIB-2 are ball valve seat configurations defined in API 6D. API 6D, API 608, ISO 17292 and ASME B16.34 each govern different valves. Fire-safe, fugitive-emission, anti-static and sour-service each name a test or a construction requirement. Actuators are sized from breakaway, run and reseat torque through an ISO 5211 flange.

• A ball valve seals by line pressure. Floating balls seat downstream; trunnion seats push upstream onto a fixed ball.
• Size and class together decide trunnion versus floating. Larger bores and higher classes push toward trunnion support.
• Seat material sets the temperature ceiling. Polymer seats derate as pressure rises; metal seats trade tightness for heat.
• Reduced bore costs flow, not isolation. Piggable pipelines still need a full-bore valve.
• DBB and DIB are seat configurations. They are defined in API 6D, not marketing labels for any two-seat valve.
• Fire-safe means a passed fire test. API 607 or ISO 10497 for soft seats, API 6FA for pipeline valves.
• Size the actuator from the highest torque. Breakaway, run or reseat, plus a documented safety factor.

• TL;DR
• Abstract
• Key Takeaways
• How a Ball Valve Works: Quarter-Turn Sealing Explained
• Floating vs Trunnion-Mounted Ball Valves
• Bore and Body Construction: Full, Reduced and V-Port
• Ball Valve Seat Materials and Temperature Limits
• DBB, DIB-1 and DIB-2: Isolation Is a Seat Configuration
• Ball Valve Standards: API 6D, API 608, ISO 17292 and ASME B16.34
• Fire-Safe, Low-Emission, Anti-Static and Sour-Service Features
• Actuators and Torque Sizing for Ball Valves
• By the Numbers
• A Ball Valve Specification Checklist for Your RFQ
• Frequently Asked Questions
• Conclusion
• References

A ball valve is a quarter-turn valve that isolates flow by rotating a bored sphere 90 degrees between two seat rings. Its purpose is on-off isolation: fully open when the bore aligns with the pipe, fully closed when the ball rotates 90 degrees. On a lever-operated valve, the lever parallel to the pipe means open.

A standard ball valve is an isolation valve, not a throttling valve, so specify it to sit fully open or fully closed. Modulating duty needs a V-port design. The gate valve vs ball valve comparison covers when to prefer a quarter-turn over a multi-turn design.

In a floating design, the ball is held only by the two seat rings. Upstream line pressure pushes the ball axially into the downstream seat, so seat contact force rises with differential pressure (Schmitt, 2019). This is downstream seating: the downstream seat carries the pressure load on the ball.

In a trunnion-mounted design, the ball is fixed on an upper and a lower trunnion, and the seats are spring-loaded. Line pressure pushes the upstream seat onto the fixed ball (Valve Magazine, 2021). This is upstream seating: the trunnions carry the pressure load into the body, and seat contact force stays more stable across the stroke.

Line pressure creates the seal in both designs, but from opposite sides. In a floating ball valve, upstream fluid pressure forces the ball onto its downstream seat. In a trunnion-mounted valve, the same pressure forces the upstream seat onto a fixed ball. The support design decides which seat seals (Valve Magazine, 2021).

The consequence for specifiers is direct: in a floating design the seat load and the torque needed to break the ball free both scale with the pressurized bore area, so larger sizes and higher pressure classes push the choice toward a trunnion design. Shinjo's ball valve range lists both families.

The words that appear on every valve datasheet:

• Body: the pressure-containing shell that holds the ball and seats.
• Ball: the spherical closure member with a through-bore.
• Bore: the through-hole in the ball; sets the flow area.
• Seat ring: the sealing ring pressed against the ball on each side.
• Stem: the shaft that transmits rotation from the operator to the ball.
• Trunnion: an upper or lower shaft that supports the ball in a trunnion-mounted design.
• Packing: the stem seal that prevents leakage past the stem to atmosphere.
• Body cavity: the space between the two seats when the valve is closed.
• End connection: how the valve joins the pipe, whether flanged, butt-weld, socket-weld or threaded.

The first specification decision after size and class is how the ball is supported. Two axes decide it together: nominal size and pressure class. Small ball valves at moderate class run economically as floating designs; larger sizes and higher classes push toward trunnion-mounted support. Seat load and operating torque grow with bore area multiplied by differential pressure, and manufacturers publish the crossover as a size-by-class table whose line moves by maker (Valve Magazine, 2021).

A floating ball valve carries the closed-bore pressure load into its downstream seat, so seat contact force and stem torque both rise with bore area multiplied by differential pressure (Schmitt, 2019). A trunnion-mounted ball valve transfers that load into the body through the upper and lower trunnions, leaving the seats to be pushed onto the ball by spring or line pressure alone (Valve Magazine, 2021).

In a floating design the ball is pinned only by the two seats, and the whole pressure force acting on the closed bore transfers into the downstream seat as contact stress (Schmitt, 2019). That force scales with the bore area multiplied by the differential pressure, so a larger bore or a higher class raises the load and both together compound it. At some combination of size and class the soft seat begins to extrude or cold-flow under the contact pressure, and the breakaway torque needed to rotate the ball grows beyond what a practical stem diameter can transmit. Trunnion support carries that pressure force into the body through the upper and lower shafts, so the seats see only their own spring or pressure-energized load, and torque stays lower and more predictable across the stroke. A construction-level comparison lives at floating versus trunnion-mounted design.

The crossover is a torque and seat-load argument, not a mechanical veto, so trunnion construction appears below the usual size and class boundary when torque predictability matters more than cost. Automated service is the common case: an actuator sized for a stable torque profile is smaller, cheaper and more repeatable than one sized for a floating valve whose breakaway grows with line pressure. Frequent-cycling duty, cryogenic service, and any line that will carry a double block and bleed function also justify the trunnion-mounted design at smaller sizes. Ask the vendor for the torque table at operating differential pressure and compare both options at the same duty.

Two datasheet lines often left to the supplier decide flow capacity and whether the valve can ever be repaired in the line: the bore and the body construction. Write both explicitly.

A full bore (also called full port) ball valve carries a ball bore that matches the pipe internal diameter (British Standards Institution, 2015b). Pressure drop is at its lowest, and a pipeline pig can pass through the open valve, which is why piggable pipeline service requires a full-bore design.

A reduced bore design (also called reduced or standard port) uses a ball bore typically one nominal size smaller than the end connection, for example an NPS 2 bore in an NPS 3 valve (British Standards Institution, 2015b). Flow capacity (Cv) drops with the bore area, but isolation performance is unchanged, and the valve costs and weighs less. For general process isolation where a small pressure drop is acceptable, reduced bore is the default choice.

A V-port ball valve replaces the round through-bore with a V-shaped opening in the ball, which gives a characterized flow curve and controllable throttling. This is the ball-valve design meant for modulating duty. For anything more demanding, follow the site's control valve selection guidance rather than repurposing an isolation valve. Deeper background sits in full port versus reduced port and V-port ball valve.

A standard ball valve must not be left partly open. High-velocity flow across the partly exposed seat wire-draws the sealing surface, and the closed valve then leaks. Specify a V-port design or a dedicated control valve for any duty that regulates flow, and keep the standard isolation model only fully open or fully closed.

Body construction decides whether seats can be replaced in the line and how many bolted joints can weep. Five constructions cover the field.

Match the choice to the maintenance plan and to how the ends are joined to the line. A three-piece body pays back on a welded line that needs regular seat changes; a fully welded body suits a buried run where every bolted joint is a future leak, at the cost of cutting the pipe if the valve ever fails.

Seat material, not body material, usually sets a ball valve's temperature ceiling, and that ceiling falls as line pressure rises. Makers publish each seat material's allowable differential pressure against temperature as a curve, so specify against the actual operating pressure and temperature, not the single headline number on a catalog page (Habonim Industrial Valves & Actuators, 2024).

Four seat families cover almost all industrial ball valve service. Virgin PTFE (polytetrafluoroethylene) is the default soft seat: easy to seal, chemically inert, but prone to cold flow at high differential pressure. Reinforced PTFE (RPTFE) adds a glass or carbon filler that resists creep and raises the allowable pressure at a given temperature rather than the temperature ceiling itself. PEEK (polyether ether ketone) is a stiffer thermoplastic used where PTFE families extrude, at the cost of higher operating torque. Metal-seated designs hard-face the ball and seat, typically with tungsten carbide or chromium carbide, and serve above the polymer range and in abrasive or severe duty.

A soft seat seals by deforming against the ball. As line pressure rises, the same polymer that seals also creeps and extrudes past the sealing lip, so the temperature at which the material still holds the ball drops. Every OEM publishes a pressure-temperature curve for each seat family; the specifier reads across from the operating pressure to find the allowable temperature, not from the single number on a catalog page. PTFE families cold-flow fastest, PEEK slowest of the polymers, and a metal seat carries the pressure through direct metal-to-metal contact rather than deformation. That contact wears in its own way: in a component test of a coated stainless steel ball and seat, surface roughness on both rose by a factor of 3 to 4, the seat wore more than the ball, and adhesive and abrasive wear dominated, changes that raise torque and leakage (Bae & Chung, 2016).

A seat material sets the polymer's own ceiling. The body carries a separate pressure-temperature rating governed by its material and pressure class, defined in ASME B16.34 for flanged, threaded and welding-end valves. A carbon steel Class 300 body and a stainless steel Class 300 body derate on different curves, and the seat inside either one derates on its own curve. API 608 turns this into a rule: the valve's pressure-temperature rating is the lesser of the shell rating and the seat rating (SVF Flow Controls, 2018). Specify both limits on the datasheet at the same operating condition, and take the lower as the ball valve's working envelope.

A ball valve specification is not one line on a datasheet, it is several: support design, bore, seat material set against temperature and pressure, the governing standard, and actuator torque with margin. Send the service conditions from your own datasheet, size, class, fluid, temperature and pressure, not just the valve type, and we can match them against Shinjo’s Ball Valves range.

DBB, DIB-1 and DIB-2 describe how a single valve's two seats behave, as API 6D defines them. A double block and bleed (DBB) valve seals against pressure from both ends through two seating surfaces with a bleed between them (American Petroleum Institute, 2021); a double isolation and bleed (DIB) valve seals against pressure from a single source at each seat, with a cavity bleed (American Petroleum Institute, 2021).

DIB-1 carries two bidirectional seats; DIB-2 carries one bidirectional seat and one unidirectional seat (American Petroleum Institute, 2021). Typical seat pairings: DBB uses two self-relieving seats, DIB-1 uses two double-piston-effect seats, and DIB-2 pairs one self-relieving seat with one double-piston-effect seat. The difference decides whether an external cavity relief valve is part of the ball valve specification.

A self-relieving seat, also called a single-piston-effect seat, is pushed onto the ball by upstream line pressure. When cavity pressure rises above line pressure, most often from thermal expansion of trapped fluid, the seat lifts off the ball and vents the excess back into the line (American Petroleum Institute, 2021). A double-piston-effect (DPE) seat is designed so pressure from either side, upstream or cavity, pushes the seat harder onto the ball. It seals against cavity pressure and cannot self-relieve, so a valve carrying one or two DPE seats needs an external cavity relief valve tapped into the body (American Petroleum Institute, 2021). The direction each seat holds against, and whether it can vent cavity pressure back to the line, is what a specifier writes per seat rather than at the configuration level.

Name the configuration by its API 6D designation, DBB, DIB-1 or DIB-2, not just "double block and bleed." For DIB-1 or DIB-2, list the external cavity relief valve as a separate line item on the RFQ and state its set pressure against the body rating. DIB-1 gives bidirectional isolation on both sides at the cost of the external relief valve; DIB-2 keeps one self-relieving seat and gives up bidirectional isolation on that side. A three-piece trunnion DBB ball valve is the common shape when the line needs isolation from both directions and self-relief through the seats.

Which standard governs a ball valve depends on the service. API 6D, with its international twin ISO 14313, governs pipeline and piping valves for the petroleum and natural gas industries (American Petroleum Institute, 2021). API 608 and ISO 17292 govern metal ball valves for refinery and process piping (British Standards Institution, 2015b; SVF Flow Controls, 2018). ASME B16.34 sets the pressure-temperature rating behind them by body material and pressure class (American Society of Mechanical Engineers, 2020).

The first question is whether the valve sits on a pipeline or on process piping. API 6D, with international twin ISO 14313, covers pipeline valves for petroleum and natural gas service, and it is also the document that defines DBB, DIB-1 and DIB-2 (American Petroleum Institute, 2021). For refinery and process-piping duty, API 608 governs metal ball valves with flanged, threaded or welding ends, and ISO 17292 is the international counterpart (British Standards Institution, 2015b; SVF Flow Controls, 2018). BS 5351 was the former British ball valve standard; it has been withdrawn and replaced by ISO 17292, though it still appears on older datasheets (Health and Safety Executive, n.d.). For a side-by-side view of the two American documents, see our note on API 6D versus API 608.

ASME B16.34 sets pressure-temperature ratings, wall thickness and materials for flanged, threaded and welding-end valves. A pressure class is a rating by body material and temperature, not a single test pressure. The valve is rated at Class 150, 300, 600, 900, 1500 or 2500, and the allowable working pressure at any operating temperature is read from the class table for the specific material (American Society of Mechanical Engineers, 2020). The standard also distinguishes Standard, Special and Limited class designations, which differ in inspection, non-destructive examination and test rigor. Name the standard and the class on the datasheet; the supplier returns the specific pressure at the specified temperature.

For valves outside the API 6D scope, purchase orders commonly call for shell and seat pressure testing to API 598. ISO 5208 classifies seat leakage by rate: Rate A is no visible leakage for the test duration, and successively looser rates follow (British Standards Institution, 2015a). Soft-seated ball valves are normally tested to zero visible leakage; metal-seated valves are specified at a looser rate agreed between buyer and supplier, and that agreed rate should appear on the purchase order alongside the acceptance criterion. For reference, the Shinjo ball valve category page lists design standards including API 6D, ASME B16.34, EN ISO 17292 and BS 5351.

Each of these words on a ball valve datasheet names either a passed test or a construction requirement, and a specification should carry the standard behind it, not the word alone. "Fire-safe design" without a fire-test report and "low-emission" without a tightness class commit the supplier to nothing measurable.

Fire-safe means the design has passed a fire type test: API 607 or ISO 10497 for quarter-turn and soft-seated valves, API 6FA for valves within the API 6D scope. The test burns the closed valve and measures leakage through the seat and to the outside, including after cooldown (Valve Magazine, 2015).

A soft seat burns away in a hydrocarbon fire, and the fire-safe design carries a secondary metal-to-metal seal that takes over so the closed valve still limits leakage after the elastomer is gone. The certificate qualifies a design, not each production valve, and it names the tested size range and pressure class. A valve outside that range is not covered by the design's approval.

Specifier note: "fire-safe design" on a catalog page is a design claim, not evidence of a passed test. Ask for the fire-test report or certificate that covers the specific valve family, size and pressure class you are ordering, not a generic brochure line.

ISO 15848-1 qualifies the stem seal by type test and classifies it on two axes: tightness class (A tightest, then B, then C) and endurance class (CO1, CO2 and CO3 for on-off valves, by number of mechanical cycles) (British Standards Institution, 2025). State both classes on the datasheet, together with the test temperature and pressure, so the specification matches what the site emissions program requires.

Anti-static construction places a spring-loaded contact between ball, stem and body so electrostatic charge from flowing fluid cannot build up in flammable service; API 608 and ISO 17292 both require the feature and specify that the measured resistance shall not exceed 10 ohms at a test voltage not greater than 12 V DC (British Standards Institution, 2015b; SVF Flow Controls, 2018). A blowout-proof stem is inserted from inside the body, so line pressure cannot push it out even if the gland packing is removed for maintenance. For cryogenic service, an extended bonnet keeps the stem packing away from the cold zone; BS 6364 covers valves for cryogenic service (British Standards Institution, 1998). A photograph of a cryogenic ball valve with an extended bonnet makes the geometry visible. For sour service, NACE MR0175 / ISO 15156 limits the hardness of wetted metals to resist sulfide stress cracking; for carbon steel the common limit is 22 HRC (British Standards Institution, 2020).

Size the actuator from the highest of breakaway, run and reseat torque published for the valve at its seat, size and differential pressure, then multiply that peak by a documented safety factor. The actuator must still deliver this torque at the MINIMUM available supply pressure or voltage; sizing at nominal supply is how automated valves stall on a bad day.

Valve makers publish torque as three numbers: the peak at unseating (breakaway), the running torque through mid-stroke, and the peak at end of travel when the seat re-engages (reseat). Owner practice multiplies the highest of the three by a safety factor between 1.25 and 2.0 to size the actuator, higher for dirty, cold or infrequently operated service.

Breakaway is the torque needed to lift the ball off the seat from a closed, static position. It rises with differential pressure and time in service. A soft-seated valve left closed under pressure and temperature for weeks develops higher breakaway than a new one because the seat has crept around the ball. Run torque is the lower value the actuator sees through mid-rotation. Reseat torque climbs again at end of travel as the seat re-engages. Sizing to run torque alone is a common cause of stalled automated valves. The maker's torque data for trunnion-mounted ball valves shows the shape of these curves.

ISO 5211 standardizes the actuator mounting flange and drive coupling so any actuator with an F10 output bolts to any valve with an F10 mounting flange (British Standards Institution, 2023). Each step up in flange size roughly doubles the torque the flange transmits:

Actuator type follows the duty: pneumatic rack-and-pinion or scotch-yoke for on-off service, electric for slower or line-powered applications, hydraulic for very high torque, plus a lever or bevel gear operator for manual duty. Fail-safe action is set at the actuator: a double-acting cylinder holds the last commanded position on air loss, while a spring-return unit drives the valve to a defined fail-open or fail-closed position on loss of supply. The fail position is a process safety decision, not a supplier default, and belongs on the RFQ.

• 230 °C virgin and filled PTFE seat ceiling at low pressure (Habonim Industrial Valves & Actuators, 2024)
• 260 °C PEEK seat ceiling with wider pressure envelope (Habonim Industrial Valves & Actuators, 2024)
• 650 °C metal-seated ceiling reported by one maker (Habonim Industrial Valves & Actuators, 2024)
• 3 to 4 factor of rise in ball and seat surface roughness after metal-seat wear (Bae & Chung, 2016)
• 10 ohms anti-static resistance ceiling under API 608 and ISO 17292 (British Standards Institution, 2015b; SVF Flow Controls, 2018)
• 22 HRC hardness limit for carbon steel in sour service (British Standards Institution, 2020)

A quotation for a ball valve is only as exact as the service conditions sent with it.

An RFQ for a ball valve must carry 13 lines: the line size and end connection, pressure class, service fluid with its temperature and pressure extremes, support design and bore, materials, design and rating standards, isolation configuration, fire and emission requirements, seat leakage rate, operator with fail position, and the documents required at delivery.

• Size and end connection: NPS or DN with flange standard and facing, butt-weld, socket-weld or threaded ends per the piping specification.
• Pressure class: Class 150, 300, 600, 900, 1500 or 2500, or the matching PN rating.
• Service conditions: fluid name and phase, maximum and minimum temperature, maximum operating and differential pressure at the closed valve.
• Support design: floating or trunnion-mounted, matched to the size and class in the maker's own crossover table.
• Bore selection: full, reduced or V-port, with full bore stated for any piggable pipeline and V-port for modulating duty.
• Body construction: one-piece, two-piece, three-piece, top-entry or fully welded, chosen for the required repair strategy.
• Materials of construction: body, ball, stem and seat, each named for the service fluid and temperature.
• Design and rating standards: API 6D, API 608 or ISO 17292 for the design, with the ASME B16.34 pressure-temperature rating.
• Isolation configuration: DBB, DIB-1 or DIB-2 per API 6D, and whether an external cavity relief valve is required.
• Safety features: fire test (API 607, ISO 10497 or API 6FA), emission class (ISO 15848-1), anti-static, and NACE MR0175 sour-service limits.
• Seat leakage test: ISO 5208 rate or API 598, zero visible leakage for soft seats or the agreed rate for metal seats.
• Operator specification: lever, gear or actuator with the ISO 5211 flange, supply pressure and fail-open or fail-closed position.
• Required documents: material certificates, shell and seat test reports, and any fire, emission or sour-service test records.

The Shinjo ball valve category page lists floating, trunnion-mounted and V-port designs across the size and class range shown there, and a request for quotation that carries the lines above can be matched item by item against what Shinjo supplies.

A ball valve is used for on-off isolation of flow in a pipeline. A quarter turn of the stem rotates a bored sphere between two seats: bore aligned with the pipe is open, bore rotated 90 degrees is closed. It is not designed for throttling.

'Standard valve' usually means a multi-turn gate or globe valve. A ball valve is a quarter-turn rotary valve for isolation; a gate valve needs many stem turns to open and closes with a wedge. For a full comparison, see gate valve vs ball valve.

Lists vary by source and no single body publishes an official 'seven types'. The families common to most classifications are gate, globe, ball, butterfly, plug, check and diaphragm valves. Each closes flow differently: a ball valve isolates with a quarter turn, a check valve prevents reverse flow.

The cost depends on size, pressure class, body and seat material, whether the valve is manual or actuated, and the installation labor to isolate, drain and refit the line. A firm quotation needs a full valve specification, so a supplier can price the exact valve and the work.

Size and pressure class together decide it. Floating designs suit smaller sizes and lower classes, where seat load and operating torque remain manageable; trunnion-mounted designs carry the pressure load into the body through the trunnions and take over as bore and class rise. Read the maker's size-by-class crossover table.

'Fire-safe' means the design has passed a fire type test: API 607 or ISO 10497 for soft-seated quarter-turn valves, API 6FA for pipeline valves. The burned closed valve is then measured for seat and external leakage. A secondary metal-to-metal seal takes over when the soft seat burns away.

DBB (double block and bleed) seals against pressure from both ends with two self-relieving seats that vent excess cavity pressure into the line. DIB-2 (double isolation and bleed) has one self-relieving seat and one double-piston-effect seat, which seals cavity pressure and needs an external cavity relief valve.

PTFE-family seats are rated by at least one maker to about 230 °C (446 °F) at low pressure; glass or carbon filling raises the pressure rating, not the ceiling. PEEK reaches about 260 °C (500 °F) with far more pressure capacity. Above that, specify metal seats and an agreed ISO 5208 leakage rate, and check each maker's pressure-temperature curve.

Size and pressure class are where a ball valve specification starts, not where it finishes. Two valves that match on nominal diameter and class can behave differently in service because the decisions that follow them decide how long the valve will hold. Support design sets the load path and the torque the actuator must overcome. Bore choice sets flow capacity and whether the line can be pigged. Body construction sets whether the valve can be repaired in place or must be cut out. Seat material sets the temperature ceiling at the operating pressure, and metal seats extend the range where polymer seats cannot go.

The governing standard, and the fire, emission, isolation and sour-service tests behind it, decide what the supplier is committing to when the words are printed on a nameplate. Actuator sizing, based on the highest of breakaway, run and reseat torque with a documented safety factor at minimum supply, sets whether the valve strokes reliably or stalls in a fault condition. A specification that names all of these lines gives a buyer a ball valve that will hold, and gives a supplier what it needs to quote one.

1. American Petroleum Institute. (2021). Specification for pipeline and piping valves (API 6D, 25th ed.). API. https://www.api.org/products-and-services/standards/important-standards-announcements/spec6d
2. American Society of Mechanical Engineers. (2020). Valves - Flanged, threaded, and welding end (ASME B16.34-2020). ASME. https://www.asme.org/codes-standards/find-codes-standards/b16-34-valves-flanged-threaded-welding-end
3. Bae, J., & Chung, K.-H. (2016). Wear characteristics of metal ball and seat for metal-seated ball valve. Journal of the Korean Society of Tribologists and Lubrication Engineers, 32(1), 32–38. https://doi.org/10.9725/kstle.2016.32.1.32
4. British Standards Institution. (1998). Specification for valves for cryogenic service (BS 6364:1998). BSI. https://doi.org/10.3403/01681278
5. British Standards Institution. (2015a). Industrial valves - Pressure testing of metallic valves (BS ISO 5208:2015). BSI. https://doi.org/10.3403/30302783
6. British Standards Institution. (2015b). Metal ball valves for petroleum, petrochemical and allied industries (BS EN ISO 17292:2015). BSI. https://doi.org/10.3403/30299750
7. British Standards Institution. (2020). Petroleum and natural gas industries - Materials for use in H2S-containing environments in oil and gas production - Part 2: Cracking-resistant carbon and low-alloy steels, and the use of cast irons (BS EN ISO 15156-2:2020). BSI. https://doi.org/10.3403/30404500
8. British Standards Institution. (2023). Industrial valves - Part-turn actuator attachments (BS EN ISO 5211:2023). BSI. https://doi.org/10.3403/30472790
9. British Standards Institution. (2025). Industrial valves - Measurement, test and qualification procedures for fugitive emissions - Part 1: Classification system and qualification procedures for type testing of stem seals for valves (BS EN ISO 15848-1:2025). BSI. https://doi.org/10.3403/30444462
10. Habonim Industrial Valves & Actuators. (2024). Seat characteristics [Data sheet]. Habonim. https://habonim.com/wp-content/uploads/2024/11/Seat-Characteristics-v2.pdf
11. Health and Safety Executive. (n.d.). British Standards Institution (BSI) [Status list of British Standards, including BS 5351]. U.K. Health and Safety Executive. https://www.hse.gov.uk/comah/sragtech/docsbsi.htm
12. Schmitt, D. (2019, April 25). Functionality and seating technology for floating ball valves. Processing Magazine. https://www.processingmagazine.com/process-control-automation/instrumentation/article/55350466/functionality-and-seating-technology-for-floating-ball-valves
13. SVF Flow Controls. (2018, November 7). API 608 standard for valve requirements [Tech brief No. 1089]. SVF Flow Controls. https://svf.net/application/files/8517/0896/4414/Tech-Brief-1089-API-608-Standard-for-Valve-Requirements.pdf
14. Valve Magazine. (2015). The past, present and future of fire testing. Valve Magazine. https://valvemagazine.com/articles/the-past-present-and-future-of-fire-testing
15. Valve Magazine. (2021, August 9). Ball valve basics. Valve Magazine. https://valvemagazine.com/articles/ball-valves-basics

Last reviewed and updated: September 2026. Author: Shinjo Valve engineering team. For valve selection support or a quotation against your service conditions, contact our team.