D342 Double Eccentric Butterfly Valve
• D342F (PTFE seat) and D342X (rubber seat) double eccentric soft-seal butterfly valve, PN6/10/16
• Six seat materials: PTFE, NBR, EPDM, FKM, Silicone, Fluorine plastic — wide temp range −268 to +250 °C
• Size range DN50–DN2000, flanged RF ends, short and long body variants
• Worm gear operated; optional pneumatic or electric actuator
• Suitable for air, water, sewage, steam, gas, oil, and corrosive media
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Product Details
The D342 double eccentric butterfly valve — the pattern the industry also calls a high performance butterfly valve (HPBV) — is a flanged, double-offset soft-seal valve with standard worm gear drive, six seat materials from −268 to +250°C, and sizes up to DN2000 across PN6, PN10 and PN16. The cam-lift disc geometry gives low operating torque, long seat life and a bi-directional bubble-tight seal that centerline wafer valves cannot match at large bores.
- Double eccentric (double-offset) disc — cam action lifts the disc off the seat, cutting friction and operating torque
- DN50–DN2000, PN6 / PN10 / PN16, flanged raised-face ends per GB/T 17241 / ISO 7005
- Worm gear drive standard; pneumatic (see D642) and electric (see D942) actuators on request
- Six soft seats: PTFE, NBR, EPDM, FKM, Silicone, FEP — service from cryogenic to 250°C
- Field-replaceable seat ring — swap the seat without removing the body from the line
- Bi-directional Class VI zero leakage per GB/T 13927; shell test at 1.5×PN
Product Overview
The D342F/D342X is a double-offset (double eccentric) soft-seal butterfly valve designed for demanding isolation and flow control applications from DN50 to DN2000. Unlike centerline wafer valves, the double eccentric geometry lifts the disc away from the seat during the opening stroke — the first offset shifts the shaft behind the disc centreline, the second offset inclines the shaft relative to the pipe axis. This cam-like motion reduces seat friction, lowers operating torque, extends seat life, and enables a tighter bi-directional seal. Flanged end connections ensure rigid pipe alignment and simplify installation in large-bore and high-pressure systems. A manual worm gear drive is standard; pneumatic and electric actuator assemblies are available on request. With six seat material options ranging from cryogenic PTFE (−268°C) to high-temperature silicone rubber (250°C), the D342 covers the widest temperature and chemical compatibility range in the Gaoshan butterfly valve portfolio.
As a factory-direct manufacturer since 1975, Gaoshan Valve supplies CE-marked, API 6D certified quality at competitive factory pricing, with standard configurations ready for fast global shipment.
Model Designation Guide
| Model Code | Pressure | Body Material | Seat Designation | Typical Application |
|---|---|---|---|---|
| D342F-6/10/16 | PN6 / 10 / 16 | Specify: —, Q, or C | F = PTFE (polytetrafluoroethylene) | Corrosive chemicals, high temperature, cryogenic |
| D342X-6/10/16 | PN6 / 10 / 16 | Specify: —, Q, or C | X = Rubber (NBR / EPDM / FKM / Silicone) | Water, air, sewage, gas, petroleum, food processing |
| Body: — | — | Gray Cast Iron / Ductile Iron | Standard body (omitted in code) | General water & low-pressure service |
| Body: Q | — | Ductile Cast Iron (QT450-10) | Example: D342F-10Q | Elevated impact / pressure shock duty |
| Body: C | — | WCB Cast Steel / Stainless Steel | Example: D342X-16C | High pressure, steam, petrochemical |
Why Double Eccentric Means High Performance
The name “high performance butterfly valve” (HPBV) and the name “double eccentric butterfly valve” describe the same pattern: two engineered offsets between shaft, disc and seat that change the disc from a rubbing seal into a cam seal.
How the Two Offsets Work
Offset one moves the shaft axis behind the disc sealing face; offset two tilts the shaft axis against the pipe axis. As the disc opens, the sealing surface separates from the seat within the first degrees of travel — the disc lifts cleanly instead of grinding around the full circumference the way a centerline disc does.
Low Torque, Longer Seat Life
Because the disc only touches the seat at the moment of closure, friction and wear drop sharply. That means a smaller, lighter worm gearbox for the same duty, easier manual operation at large sizes, and a seat that keeps its seal over many more cycles — the gearbox functional test verifies torque and limit settings on every valve.
Large-Bore Capability
The same geometry is what lets the pattern scale to DN2000 at PN6–PN16 with rigid flanged ends, where centerline wafer valves run out of size at DN500. That is why double eccentric valves are the default on water transmission mains, pump station headers and large plant cooling lines.
Double Eccentric vs. Centerline Butterfly Valve
| Feature | D342 Double Eccentric | D71X / D371X Centerline |
|---|---|---|
| Disc motion | Cam-lift (wiping action) | Rub / compress against seat |
| Seat friction during opening | Minimal — lifts off clean | Moderate — compression drag |
| Max size | DN2000 | DN500 |
| End connection | Flanged (RF) | Wafer |
| Seat replaceability | Yes — serviceable insert | Bonded to body |
| Seat material range | 6 materials, −268 to 250 °C | NBR only, max 135 °C |
| Best for | Critical service, large bore, aggressive media | General industrial, small-medium bore |
Key Advantages
Double Eccentric Cam Action
The dual-offset shaft design generates a cam-like wiping motion as the disc opens: the disc lifts cleanly from the seat face with minimal sliding friction, reducing wear and operating torque.
6 Seat Materials, −268 to +250 °C
Choose from PTFE, NBR, EPDM, FKM, Silicone, or FEP to match any process media and temperature: from cryogenic liquefied gases through to saturated steam and hot oils.
Flanged Rigid Installation
Integrated cast-in flanges with raised-face (RF) sealing face eliminate the need for separate flange adaptors and provide rigid pipe alignment for large-bore DN2000 installations.
Short & Long Body Variants
Two face-to-face lengths — short (compact) and long (standard) — allow drop-in replacement of existing butterfly valves without pipe modifications.
Replaceable Seat Ring
The seat is retained as a serviceable insert: when the elastomer ages or the application changes, the seat can be replaced in-situ by the user without removing the valve body from the pipeline.
Bi-Directional Bubble-Tight Seal
The double eccentric geometry + soft seal achieves zero-leakage performance in both flow directions at rated pressure, meeting Class VI shutoff per GB/T 13927.
Seat Material Selection Guide
| Material Code | Seat Material | Max Temp | Min Temp | Working Temp | Best For |
|---|---|---|---|---|---|
| X (FKM) | Fluorine Rubber (Viton) | 82 °C | −40 °C | ≤65 °C | Oils, fuels, chemical media at moderate temp |
| J (NBR) | Nitrile Rubber (Buna-N) | 93 °C | −40 °C | ≤80 °C | Water, petroleum, oil, general industrial |
| YBX (EPDM) | Ethylene Propylene Diene Monomer | 150 °C | −40 °C | ≤120 °C | Steam, hot water, polar fluids, HVAC |
| F (PTFE) | Polytetrafluoroethylene (Teflon) | 232 °C | −268 °C | ≤200 °C | Strong acids, oxidisers, cryogenic, high-temp dry |
| GX (VMQ) | Silicone Rubber | 250 °C | −70 °C | ≤200 °C | Food processing, pharmaceuticals, high-temp air |
| FJ (FEP) | Fluorine Plastic (Fluorinated Polyethylene) | 204 °C | −23 °C | ≤180 °C | Chemical processing, semi-corrosive, high temp |
Applicable Media by Seat Type
- Water / Seawater
- Sewage / Wastewater
- Steam (≤250 °C)
- Compressed Air
- Natural Gas / Coal Gas
- Petroleum / Fuel Oil
- Weak Acid
- Alkali / Caustic
- Food / Beverage
- HVAC Hot/Chilled Water
- Fire Protection
- Cryogenic (LNG / LOX)
Technical Specifications
| Parameter | PN6 | PN10 | PN16 |
|---|---|---|---|
| Nominal Pressure | 6 bar (0.6 MPa) | 10 bar (1.0 MPa) | 16 bar (1.6 MPa) |
| Shell Test Pressure | 0.9 MPa | 1.5 MPa | 2.4 MPa |
| Seal Test Pressure | 0.66 MPa | 1.1 MPa | 1.76 MPa |
| Air Tightness Test | 0.6 MPa | 0.6 MPa | 0.6 MPa |
| Size Range | DN50 – DN2000 (2″ – 80″) | DN50 – DN2000 (2″ – 80″) | DN50 – DN2000 (2″ – 80″) |
| End Connection | Flanged, Raised Face (RF) per GB/T 17241 / ISO 7005 | Flanged, Raised Face (RF) per GB/T 17241 / ISO 7005 | Flanged, Raised Face (RF) per GB/T 17241 / ISO 7005 |
| Disc Type | Double eccentric (double-offset) disc | Double eccentric (double-offset) disc | Double eccentric (double-offset) disc |
| Operation | Worm gear (standard); pneumatic / electric actuator optional | Worm gear (standard); pneumatic / electric actuator optional | Worm gear (standard); pneumatic / electric actuator optional |
| Seat Type | Soft-seal: PTFE, NBR, EPDM, FKM, Silicone, or FEP | Soft-seal: PTFE, NBR, EPDM, FKM, Silicone, or FEP | Soft-seal: PTFE, NBR, EPDM, FKM, Silicone, or FEP |
| Applicable Medium | Air, water, sewage, steam, gas, oil, weak acid, alkali | Air, water, sewage, steam, gas, oil, weak acid, alkali | Air, water, sewage, steam, gas, oil, weak acid, alkali |
| Design Standard | GB/T 12238; GB/T 13927 (pressure test) | GB/T 12238; GB/T 13927 (pressure test) | GB/T 12238; GB/T 13927 (pressure test) |
Materials of Main Parts
| Component | Standard (—) | Q Body | C Body |
|---|---|---|---|
| Body | Gray Cast Iron / Ductile Iron | Ductile Cast Iron (QT450-10) | WCB Cast Steel / SS |
| Disc | Gray Cast Iron / Ductile Iron | Ductile Cast Iron | Cast Steel / Stainless Steel |
| Seat Ring | PTFE / NBR / EPDM / FKM / Silicone / FEP (as selected) | PTFE / NBR / EPDM / FKM / Silicone / FEP (as selected) | PTFE / NBR / EPDM / FKM / Silicone / FEP (as selected) |
| Stem / Shaft | 2Cr13 Stainless Steel / SS304 / SS316 (on request) | 2Cr13 Stainless Steel / SS304 / SS316 (on request) | 2Cr13 Stainless Steel / SS304 / SS316 (on request) |
| Stem Packing | O-Ring (NBR/FKM) / Flexible Graphite | O-Ring (NBR/FKM) / Flexible Graphite | O-Ring (NBR/FKM) / Flexible Graphite |
| Worm Gear | Ductile Iron housing; alloy steel worm & gear | Ductile Iron housing; alloy steel worm & gear | Ductile Iron housing; alloy steel worm & gear |
| Fasteners | Carbon Steel / Stainless Steel (as specified) | Carbon Steel / Stainless Steel (as specified) | Carbon Steel / Stainless Steel (as specified) |
Principal Dimensions (mm) — All Pressure Classes
| DN | in. | L (Short) | L (Long) | H1 | H | L1 | L2 | D1 |
|---|---|---|---|---|---|---|---|---|
| 80 | 3 | 114 | 180 | 102 | 390 | 52 | 127 | 160 |
| 100 | 4 | 127 | 190 | 112 | 430 | 52 | 127 | 160 |
| 125 | 5 | 140 | 200 | 128 | 483 | 52 | 127 | 160 |
| 150 | 6 | 140 | 210 | 145 | 520 | 52 | 127 | 160 |
| 200 | 8 | 152 | 230 | 185 | 668 | 80 | 150 | 240 |
| 250 | 10 | 155 | 250 | 220 | 725 | 80 | 150 | 240 |
| 300 | 12 | 178 | 270 | 250 | 788 | 80 | 150 | 280 |
| 350 | 14 | 190 | 290 | 280 | 848 | 80 | 150 | 280 |
| 400 | 16 | 216 | 310 | 316 | 1004 | 136 | 218 | 320 |
| 450 | 18 | 222 | 330 | 344 | 1058 | 136 | 218 | 320 |
| 500 | 20 | 229 | 350 | 370 | 1145 | 136 | 218 | 320 |
| 600 | 24 | 267 | 390 | 440 | 1380 | 124 | 238 | 500 |
| 700 | 28 | 292 | 430 | 505 | 1475 | 124 | 238 | 500 |
| 800 | 32 | 318 | 470 | 570 | 1600 | 124 | 238 | 500 |
| 900 | 36 | 330 | 510 | 630 | 1742 | 176 | 259 | 500 |
| 1000 | 40 | 410 | 550 | 690 | 1866 | 176 | 259 | 500 |
| 1200 | 48 | 470 | 630 | 820 | 2200 | 176 | 259 | 500 |
| 1400 | 56 | 530 | 710 | 950 | 2530 | 292 | 371 | 560 |
| 1600 | 64 | 600 | 790 | 1100 | 2850 | 290 | 371 | 560 |
| 1800 | 72 | 670 | 870 | — | 1796 | — | — | — |
| 2000 | 80 | 760 | 950 | — | 3075 | — | — | — |
L (Short) = compact face-to-face, L (Long) = standard face-to-face; H1 = centerline to top of valve body; H = overall gearbox height; L1 = gearbox width; L2 = gearbox depth; D1 = flange bolt-circle diameter. All values in mm. PN6 / PN10 / PN16 share identical face-to-face dimensions. — = consult factory for DN1800–DN2000 actuator dimensions.
Worm Gear Drive & Actuator Options
The D342 ships with a self-locking worm gear as standard — the right choice for large bores that are operated infrequently and need positive mechanical locking in position. Where the line must respond to a control signal or take a defined fail-safe position, step up to the pneumatic D642 or the electric D942 on the same double eccentric body.
Butterfly Valve Family at a Glance
| Type | Models | Seat | Characteristics | Typical Service |
|---|---|---|---|---|
| Centerline wafer | D71X / D371X / D671X / D971X | Rubber (NBR / EPDM) | Lightest & most economical; PN10 / PN16; ≤135°C | Water, HVAC, general service |
| Double eccentric (high performance) | D342 (this page) / D642 / D942 | Rubber / PTFE | Large bores, PN6–PN16, low operating torque | Water mains, large pipelines |
| Triple offset (metal seated) | D343H / D363H | Laminated metal | High temperature & high pressure service | Steam, hot oil, petroleum |
Browse the whole butterfly valve series or compare the double eccentric drive options: D342 (worm gear), D642 (pneumatic) and D942 (electric).
Structure Drawing
Quality Assurance & Testing
Every D342 butterfly valve undergoes the following factory acceptance tests before shipment:
- Shell Pressure Test — hydrostatic test at 1.5×PN to verify body and flange integrity.
- Seat Leakage Test — bi-directional water or air test at 1.1×PN; Class VI zero leakage per GB/T 13927.
- Air Tightness Test — pneumatic seat test at 0.6 MPa to confirm bubble-tight shutoff in gas service.
- Gearbox Functional Test — full open/close cycle under differential pressure; torque and limit verification.
- Dimensional Inspection — face-to-face (short & long), flange bolt-circle, and bore dimensions per GB/T 12238.
- Seat Material Verification — each seat lot is hardness-tested and thermally qualified against the selected material specification.
Installation & Maintenance Notes
- Orientation: Install with the shaft horizontal or vertical (preferred for DN600+). Ensure adequate clearance above the gearbox for handwheel operation.
- Flange alignment: Align pipe flanges precisely before inserting the valve. Use full-face or spiral-wound gaskets compatible with the media and temperature.
- Disc position during installation: Leave the disc slightly open (5°–10°) to protect the seat edge from flange face damage during bolt tightening.
- Seat replacement: The soft seat is a field-replaceable insert. No special tools required — remove retaining ring, swap seat, re-torque evenly.
- Periodic inspection: Inspect the seat every 6–12 months. Replace if cracking, swelling, or permanent set exceeding 10% of original thickness.
- Gearbox lubrication: Check worm gear grease every 2,000 cycles. Replenish with EP2 lithium grease or as specified by the actuator manufacturer.
International Standards & Certification
The D342 is manufactured and tested to Chinese national standards with international equivalents available on request: face-to-face dimensions to GB/T 12238, pressure testing to GB/T 13927, and flange drilling to GB/T 17241 / ISO 7005 as standard. On request we quote and certify to EN 593 or API 609 design equivalents, and an ISO 5211 actuator mounting pad can be machined for actuated versions.
- CE-marked (EU PED) and holding API 6D plus ISO 9001 / ISO 14001 / ISO 45001 management system certification
- China pressure-pipeline valve manufacturing license held by the factory
- Every valve passes shell and seat leakage tests before shipment; factory inspection report included
- EN 593 / API 609 / ISO 5211 conformance documentation on request
Why Buy D342 from Gaoshan Valve
Gaoshan Valve has manufactured industrial valves since 1975 and is CE-marked with API 6D and ISO 9001/14001/45001 certification. We are an approved supplier to Sinopec, CNPC and State Grid, exporting to more than 30 countries.
- 50-year factory — manufacturing industrial valves since 1975
- Certified quality — CE (EU PED), API 6D, ISO 9001/14001/45001, China pressure-pipeline valve manufacturing license
- Trusted by majors — approved supplier to Sinopec, CNPC and State Grid; exports to 30+ countries
- 100% tested — shell test at 1.5×PN, bi-directional seat test at 1.1×PN, gearbox torque verification
- Seat traceability — certified inspection reports and seat material traceability with every valve
Frequently Asked Questions
Is a double eccentric butterfly valve the same as a high performance butterfly valve?
Yes. “Double eccentric” describes the two-offset shaft geometry and “high performance butterfly valve” (HPBV) is the market name for the same pattern. The cam-lift action gives lower torque, longer seat life and a bi-directional bubble-tight seal than a centerline wafer valve.
Why does the D342 need less operating torque than a centerline valve?
The double-offset geometry lifts the disc off the seat within the first degrees of travel, so the disc only contacts the seat at closure instead of rubbing through the whole stroke. Less friction means a smaller worm gearbox and easier manual operation at large sizes.
How large can the D342 be supplied, and at what pressure?
From DN50 to DN2000 at PN6, PN10 and PN16, with flanged raised-face ends. Centerline wafer patterns stop at DN500; the double eccentric design with rigid cast-in flanges is the pattern used for large-bore mains.
Can the seat be replaced without removing the valve from the pipeline?
Yes. The soft seat is retained as a serviceable insert: remove the retaining ring, swap the seat and re-torque evenly — no special tools and no body removal required.
Which seat material should I choose?
Match the media and temperature: PTFE for strong acids and cryogenic service down to −268°C, EPDM for steam and hot water to 120°C, NBR for water and petroleum to 80°C, FKM for oils and fuels, Silicone for food processing to 200°C, FEP for semi-corrosive chemical duty.
What standards and certifications come with the valve?
Design to GB/T 12238, pressure testing to GB/T 13927 (Class VI zero leakage), flange drilling to GB/T 17241. Gaoshan Valve is CE-marked with API 6D and ISO 9001/14001/45001 certification; EN 593 / API 609 / ISO 5211 documentation is available on request.
Ordering Information
| Item | Specify When Ordering |
|---|---|
| Model | D342F or D342X — plus pressure class (6 / 10 / 16) and body designation (, Q, or C) |
| Nominal Size | DN50 – DN2000 |
| Face-to-Face Length | Short (compact) or Long (standard) |
| Seat Material | FKM (X) / NBR (J) / EPDM (YBX) / PTFE (F) / Silicone (GX) / FEP (FJ) |
| Disc Material | Ductile Iron (standard); SS304 / SS316 / Special alloy on request |
| Shaft Material | 2Cr13 (standard); SS304 / SS316 / Duplex on request |
| Flange Standard | GB/T 17241 (standard); ANSI B16.5 / DIN EN 1092 on request |
| Actuator Option | Worm gear (standard); pneumatic (DA/SR); electric (on/off/modulating) |
Related Butterfly Valves
D642 Pneumatic Double Eccentric Butterfly Valve — the same double eccentric body with pneumatic actuation. D942 Electric Double Eccentric Butterfly Valve — electric actuated double eccentric. D343H Triple Eccentric Hard-Seal Butterfly Valve — triple offset metal-seated valve for high-temperature service. D371X Gear-Operated Wafer Butterfly Valve — economical gear-operated centerline wafer valve for small bores.
Get a Quote & Technical Support
Gaoshan Valve supplies D342 double eccentric butterfly valves with certified inspection reports, seat material traceability, and actuator documentation. Reverse-engineering support available for legacy valve replacement. Contact our team for pricing, CAD drawings, and application-specific seat recommendation — reply within 24 hours.
