Double Eccentric Butterfly Valve rubber seated
The double eccentric butterfly valve — also known as a double offset butterfly valve — features a unique disc geometry where the shaft is offset from both the centerline of the disc and the centerline of the pipe. This dual offset design allows the disc to cam away from the seat immediately upon opening, eliminating continuous contact between disc and seat during operation.
The result is significantly reduced operating torque, minimized seat wear, and extended service life compared to concentric butterfly valves. When fully open, the disc has zero contact with the seat, ensuring the sealing surface remains undamaged over thousands of operating cycles.
The sealing ring is made of elastomer, fitted into the disc and secured by a cover plate, forming a continuous, uninterrupted sealing surface around the full circumference. This design provides reliable bi-directional sealing performance and is commonly specified for municipal waterworks, water treatment plants, and large-diameter pipeline systems.
Suitable for uni-directional and bi-directional sealing applications. Standard pressure rating ANSI Class 150 / PN10 / PN16 / PN25.
Double Eccentric Design — the double offset disc geometry means the disc cams away from the seat after just a few degrees of opening, eliminating seat friction throughout the stroke and dramatically extending seat life compared to concentric designs.
The tension on the disc is released after a few degrees of opening, minimising wear of the disc seal. The design also minimises seat compression, ensuring low operating torques throughout the valve's service life.
The integral seat design features a machined and epoxy-coated ductile iron seat integrated in the body. The stainless steel seat design offers a replaceable seat ring sealed with an O-ring to prevent leakage under the seat ring.
Shaft sealing is fully replaceable under pressure, enabling easy field maintenance without line shutdown. EPDM seals ensure internal tightness; NBR seals protect against external impurities and fluid ingress.
The disc seal geometry ensures correct positional fixation and reliable function. High-quality rubber compound allows reduced seal volume, delivering low closing torques. EPDM sealing is ACS and WRAS approved for potable water applications.
| Design & manufacture | EN 593 / API 609 |
| End connection | Double flanged |
| Operation | Manual / Pneumatic / Electric |
| Size range | NPS 14"–120" (DN350–DN3000) |
| Pressure rating | PN10 / PN16 / PN25 | ANSI Class 150/275/500 |
| Face to face | EN 558-1 Series 13 / Series 14 |
| Flange end | EN 1092-2 / ASME B16.5 / AWWA C207 / ASME B16.47 |
| Inspection | EN / AWWA C504 / C519 / NSF 61/372 |
| Body | ASTM A536 65-45-12 / GGG-40 / GGG40.3 / SS 1.4408 |
| Disc / Plate | DI+Ni / CF8 / CF8M / C954 / C958 / GGG-40 / SS 1.4408 |
| Shaft / Stem | SS431 / SS420 / SS410 / SS304 / SS316 |
| Seat / Lining | NBR / EPDM / Viton / PTFE / PFA |
| Taper pins | SS416 / SS316 |
| Bushing | Brass / PTFE |
| O-ring | NBR / EPDM / Viton / PTFE |
| Key | Steel |
