API · ASME · DIN · EN standard industrial valves
Concentric Butterfly Valves
Concentric butterfly valves keep the stem centered in the disc and the disc centered in the bore, so the rubber-seated disc bears evenly all round — the economical, lightweight quarter-turn choice for low-pressure utility and general industrial service. The range covers 2" to 72" (DN 50 to DN 1800) at PN6-PN16 (85-232 psi), in ductile iron, carbon steel, stainless steel or bronze bodies with wafer, lug and RF flanged ends, lever, gear, pneumatic, electric or hydraulic operation. Sealing is elastomer-based — EPDM (drinking-water WRAS), NBR (oil service) or PTFE (pH 1-14 corrosive media) — with EN 12266 Class A zero-leakage shutoff on referenced soft-seal builds and dovetail/pressure-ring seats replaceable in line. Because the disc rubs the seat through part of its travel, seat friction, torque (≈90-degree stroke, ≤80 N-m manual at DN200 on referenced builds), temperature (-20 to 120 C typical, -40 C with 304L upgrade) and media compatibility set the duty limits; higher temperature or pressure moves to single- and multi-offset designs. Standards span API 609, MSS SP-67, ISO 17292, GB/T 12238 and EN 593, with API 598 hydro acceptance and API 607 fire-safe certification available.
Part of the Butterfly Valves family
Last updated: 2026-11
Family specifications
| size range | 2”~72”(DN50-DN1800) |
|---|---|
| pressure class | 85~232Psi（PN6~PN16） |
| seat materials | NBR, EPDM, PTFE |
| disc materials | Ductile Iron, SS304, SS316 |
| stem materials | Stainless Steel 420, Stainless Steel 410 |
| body materials | Ductile Iron, Carbon Steel, Stainless Steel, Copper |
| end connections | Wafer, Lug, RF |
| operation | Lever, Gear, Pneumatic, Electric, Hydraulic |
| leakage class | Seat leakage on the referenced line is specified at EN 12266 Class A with a leakage rate of 5x10-8 m3/s or less, i.e. zero-leakage soft-seal shutoff. |
| temperature range | 0 to 80 C |
| design standards | API 609 |
| design standards | DIN 3202, DIN 2501 PN10/PN16 |
| face to face | BS 5155 |
| zero offset definition | Definition: a concentric butterfly valve is a quarter-turn valve in which the shaft, disc centre and body centreline are aligned in a zero-offset arrangement, so the disc edge compresses a resilient seat to seal. |
| sealing principle | Sealing is elastomer-based: soft seat materials such as EPDM, NBR or PTFE let the disc press firmly into the seat for a leak-proof seal without excessive torque. |
| seat temp pressure limits | Elastic seats set the operating ceiling: high-temperature or abrasive media compromise the seat, which is why the type is generally kept to moderate conditions. |
| seat friction torque | Because the disc rubs against the resilient seat through part of its travel, seat friction, operating torque, temperature limits and media compatibility must be checked at selection rather than assumed. |
| standards frame | Applicable standards span API 609 (wafer/lug/double-flanged), MSS SP-67, ISO 17292 for petroleum service and GB/T 12238 for flanged and wafer connection valves; EN 593 is cited as the European counterpart. |
| standards project dependent | The exact standard and edition are product- and project-dependent; buyers should specify API 609 or EN 593 plus the required inspection and leakage test requirements. |
| size envelope oem | A representative OEM concentric soft-seal line covers DN40-DN1200 as standard with DN1400-DN2000 available only after engineering evaluation - well inside the tenant band of DN50-DN1800. |
| pressure envelope oem | Standard pressure ratings are PN10/PN16 (1.0/1.6 MPa) with a PN25 (2.5 MPa) upgrade path on the referenced execution. |
| temperature envelope | The referenced soft-seal execution serves water, air and oil media from -20 C to 120 C; a low-temperature tested variant to -40 C requires a 304L material upgrade. |
| low temp option | Cryogenic-leaning duties are handled by option rather than standard build: the referenced line lists low-temperature testing to -40 C with material upgraded to 304L. |
| seat material specifics | Seat media matching: EPDM for drinking water (WRAS certified), NBR for oil media (ASTM No. 3 oil test) and PTFE for strongly corrosive service across pH 1-14. |
| seat replaceability | The seat is retained by a dovetail groove or pressure ring so it can be replaced online without removing the valve from the line after wear. |
| lug end function | The lug body carries threaded inserts both sides, letting the valve be installed independent of the downstream flange so pipework can be opened for maintenance without draining the system. |
| connection classification | Connection variants beyond wafer/lug include double-flange bodies for higher pressure or larger diameter and butt-weld bodies welded permanently into petrochemical lines. |
| open flow resistance | Even fully open the disc and shaft remain in the flow passage, so some pressure loss persists and scales with diameter and disc/shaft geometry. |
| eccentric development | The single-eccentric (offset) design exists specifically to answer concentric wear: offsetting the stem from the disc centre reduces friction, extends sealing life and opens the door to higher temperature and pressure duties. |
| actuation torque | Manual builds use a fixed 90-degree stroke with limit-stop feedback; on the referenced line lever operation needs no more than 80 N-m at DN200. |
| testing frame | Acceptance testing on the referenced line runs to API 598 hydrostatic at 1.5 times rating, with API 607 fire-safe certification available through a metal-seal redundancy design. |
| seat temperature ratings table | Buna-N seat: +10 to 180 °F (-12 to 82 °C), EPDM seat (2"–16"): -30 to 275 °F (-34 to 135 °C), EPDM seat (18" and above): -30 to 225 °F (-34 to 107 °C), fluoroelastomer (FKM) seat: 10 to 400 °F (-12 to 204 °C) |
| tight shutoff pressure rating | pressure ratings for tight shutoff up to the seat material temperature limit on wafer and lug bodies: 200 psi for 2"–12" and 150 psi for 14"–72" |
| double flange tight shutoff pressure rating | pressure ratings for tight shutoff up to the seat material temperature limit on double-flanged bodies: 232 psi for 3"–14" and 150 psi for 16"–72" |
| cv fullopen wafer lug | full-open Cv (US-GPM at 1 psi ΔP) spans 115 at 2 in to 73,426 at 30 in on wafer and lug style bodies |
| cv partial open 70deg | Cv at 70° disc opening spans 70 at 2 in to 44,545 at 30 in (US-GPM at 1 psi ΔP) |
| cv partial open 50deg | Cv at 50° disc opening spans 27 at 2 in to 17,010 at 30 in (US-GPM at 1 psi ΔP) |
| torque test basis sizing | seating/unseating torque charts derived from test data with water at 60°F; dry-gas duties multiply by 2.0; figures carry no safety factor — multiply by 1.2 for single-valve actuator sizing or 2.0 for three-way (tee) applications |
| vacuum service rating | vacuum service rating: zero leakage at 24 in Hg vacuum |
| dead end pressure rating | bi-directional dead-end service capability to 200 psi (2"–12") and 150 psi (14"–24") is standard on lug style valves |
| asme flange compatibility | compatible with ASME B16.1 and ASME B16.5 flanges (2"–24"), compatible with ASME B16.47 Series A (MSS SP-44) flanges (28"–72") |
| mss design compliance | designed to comply with MSS SP-67 and MSS SP-25 |
| awwa proof of design | valves 2"–20" meet the intent of and have passed the AWWA C504-87 Section 5 proof of design tests |
| potable water ped certification | CE/PED certification available for 2"–24", NSF/ANSI 61 & 372 certified for potable water and lead-free service (aluminium-bronze or stainless steel builds) |
| marine type approval | type approval certification from ABS and USCG Category A for marine applications (2"–24") |
| seat temperature service caveats | at low temperature the elastomer durometer changes — the hardened seat may increase operating torque beyond the structural limits of the stem and/or disc-to-stem configuration, published temperature ranges may have to be modified in valve duty; ranges shown are adjusted accordingly, on the fluoroelastomer (FKM) seat build the operating pressure is reduced above 275°F, field replacement of seats in sizes 14" and above requires factory service |
| composite execution envelope | composite-body resilient seated wafer line: DN 40 to 300 (NPS 1.5 to 12), -40 to +150 °C (-40 to +300 °F), 10/16 bar (145/232 psi), flange drilling DIN PN 6/10/16, ASME 150, JIS 10K and AS 2129 Table E |
| face to face resilient composite | face-to-face per EN 558-1/Table 5 and API 609 |
| iso5211 integrated top plate | integrated ISO 5211 top plate: actuator flange per ISO 5211 without a separate mounting bracket |
| line velocity limit | usable in high line velocity applications up to 12 m/sec |
| bidirectional leak rate | bubble-tight shut-off in both directions per EN 12266-1 leak rate A |
| water marine approvals | water approvals KIWA, WRAS and NSF; certified and approved per Det Norske Veritas (DNV) |
| iso5211 pad series by size | ISO 5211 pad series F-05 (DN40–DN50), F-07 (DN65–DN150) and F-12 (DN200–DN300) |
| shaft diameter envelope | shaft diameter (h9 class) 12 mm at DN40–DN50 up to 25 mm at DN250–DN300 |
| stem seal dual design | primary stem sealing exceeds the valve pressure rating and prevents shaft-area leakage to atmosphere; a secondary shaft sealing provides back-up safety |
| kv fullopen largest size | highest tabulated Kv/Cv value is 9,872.0 / 11,452.00 at the largest listed size fully open (90° column) |
| composite weight envelope | valve mass 0.6 kg (DN40) rising to 10.8 kg (DN300) on the composite execution |
| face to face din series | face-to-face EN 558 Series 20, face-to-face ISO 5752 Series 20, face-to-face API 609 Table 1 |
| flange accommodation standards | flange drilling EN 1092 PN 6/10/16, ASME Class 150, AS 4087 PN 16, flange face EN 1092 Form A/B, ASME RF/FF |
| top flange iso5211 marking | top flange per EN ISO 5211; valve marking per EN 19 |
| tightness dual standard | tightness check per EN 12266 leakage rate A and ISO 5208 Category 3 |
| extended temp pressure envelope | a resilient wafer execution rated -40°C to +200°C (depending on pressure, medium and material) at a maximum operating pressure of 16 bar |
| kv test basis throttling | Kv is the water flow in m³/h at 5°C to 30°C (41°F to 86°F) at 1 bar ΔP; published Kv values based on tests by the Delft Hydraulics Laboratories (Netherlands); throttle function linear between 30° and 70° opening |
| flow velocity limits | permissible flow velocity max. 4.5 m/s for liquids and max. 70 m/s for gases |
| breakaway torque basis | published torque values are initial breakaway torques taken with liquids and lubricating media, to be treated as approximate: the effective value depends on pressure, medium, rubber quality and temperature |
| shaft guidance design | triple shaft bearings prevent shaft deflection and guarantee valve guidance over long service; four flange mounting holes locate the valve between flanges; installation in any desired position; maintenance-free |
| seat material code options | seat material options NBR, EPDM, CSM, FPM and VSI |
| shaft material options | shaft material options stainless steels X39CrMo17-1 and X14CrMoS17, or nickel-molybdenum alloy |
| size | 2”~72”(DN50-DN1800) |
| end connection | Wafer, Lug, RF |
| medium | Water, Oil, Gas |
| top flange | ISO 5211 |
Scope & source notes
| size envelope | Size envelope: tenant band DN50-DN1800 (2in-72in) exceeds the referenced Tianyu standard range DN40-DN1200, which only reaches DN1400-DN2000 after engineering evaluation - the tenant band is an aggregate of OEM envelopes, not one build. |
|---|---|
| pressure framing | Pressure framing: tenant reference 85-232 psi (PN6-PN16) matches the standard PN10/16 builds, but the Tianyu line offers a PN25 (2.5 MPa) upgrade path that sits outside the tenant reference range. |
| standard coverage | Standard coverage: existing design_standard lists API 609 only, while industry practice spans API 609, MSS SP-67, ISO 17292, GB/T 12238 and EN 593 - edition and scope are project-dependent. |
| leakage claim | Leakage claim: EN 12266 Class A zero-leakage soft-seal shutoff is a referenced-OEM figure; hard-seated or high-temperature builds will not meet the same class. |
Ordering & documentation
Documents
Ask for the documentation set with the inquiry — typical items (material certificates, test reports to the listed inspection standard, dimensional drawings) are confirmed and supplied with the quotation.
Quotation
Send the medium, temperature, pressure, size and connection for a quotation-ready inquiry. Lead time, MOQ and price are confirmed at quotation, together with the documents to be supplied with the order.
Sample & supply
Supply terms, order quantities and lead time are agreed per order — state the destination country and required schedule with the inquiry.
Storage & shipping
Store valves with seats and seals protected from UV, ozone and deformation, and keep end-face protectors on until installation; storage limits and shipping arrangements for the selected materials are confirmed at quotation.
Frequently asked questions
What standards govern the design and testing of concentric butterfly valves?
The published specification for this family lists API 609 as the design standards.
What sizes and pressure ratings are available for concentric butterfly valves?
The published size range is 2”~72”(DN50-DN1800), and the published pressure ratings are 85~232Psi（PN6~PN16）. Availability of a specific size and rating is confirmed at quotation.
What materials are concentric butterfly valves available in?
The published specification lists body materials: Ductile Iron, Carbon Steel, Stainless Steel, Copper. Material availability for a specific size and rating is confirmed at quotation.
What working temperature range do concentric butterfly valves cover?
The published working temperature range is 0 to 80 C. For a medium at the edge of the range, confirm the suitability of the selected seat and body materials at quotation.
What end connections do concentric butterfly valves support?
The published specification lists Wafer, Lug, RF as the available end connections. The connection for a specific size is confirmed at quotation.
What should a quotation inquiry for concentric butterfly valves include?
The governing standard and class, nominal size, body and seat materials, the service medium with temperature, and the destination — anything missing is confirmed during quotation.
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