Butt Welded Eccentric Butterfly Valve

Size: 2" - 24" (DN50 - DN600)

Pressure: Class 150 - 600 / PN 10-100

Standard: ASME B16.34, API 609, ISO 15848

Body Materials: A216 WCB, A182 F316 (forged for smaller sizes), A351 CF8M

Seat: Metal-to-metal (Stellite 6 overlay) or multi-layer composite seat (metal base + flexible graphite)

Design: Butt-weld end connections (beveled per ASME B16.25), double eccentric or triple eccentric geometry

No Flanges, No Gaskets, No Leak Paths

Every flanged connection has two failure points: the gasket and the bolts. Gaskets age and compress unevenly. Bolts relax under thermal cycling, lose preload, and the gasket drops below sealing compression—now you've got a leak path you can't see until it shows up as emissions or a drip on the floor. At Class 600+, flanged connections require heavy bolting and thick gaskets, and they're still the weakest seal in the line.

Butt-weld ends eliminate both. Valve ends are beveled per ASME B16.25. Weld them directly to the pipe. No gasket between valve and pipeline. No bolt pattern to maintain. No external leak path. Once the weld is made, inspected, and accepted, that connection is permanent. It doesn't age. It doesn't relax. It doesn't leak.

This matters in three scenarios. Class 600+ high-pressure lines where every flange is a maintenance item and emissions source. Buried or submerged installations where bolt retorquing requires excavation. Fire-safe systems where gaskets burn—welded joints don't.

Welded In Means Permanent

The tradeoff is straightforward. A butt-welded butterfly valve cannot be removed without cutting it out. When you weld this valve into the line, it becomes a permanent pipeline component.

That's why some installations specify butt-welded ends. Underground vaults, submarine crossings, high-pressure fire-safe lines where you want minimum external leak points—permanent installation is the correct engineering choice. You plan for it to stay for the life of the pipeline.

If your installation requires periodic valve removal, specify flanged ends. Butt-welded is for permanent service.

Eccentric Geometry Protects Both Seat Types

Cam-action disc rotation from double or triple eccentric geometry lifts the disc off the seat immediately instead of sliding. For the Stellite 6 metal-to-metal seat, that means no grinding across the hard facing every cycle—the overlay survives abrasive and high-temperature service. For the multi-layer composite seat, the graphite layer isn't scraped away during rotation—bubble-tight performance holds across thousands of cycles.

Lower seat friction also reduces operating torque. Smaller actuators, easier manual operation. On a valve permanently installed in an underground vault, lower torque means no oversizing—less weight, less maintenance in inaccessible locations.

A: Zero external leak path at the valve-to-pipeline connection. No gasket, no bolts, no mechanical seal that relaxes over time. The welded joint is permanent and code-compliant.

A: Only by cutting the welds. This is a permanent installation valve. If the application requires periodic removal, specify flanged ends.

A: Metal-to-metal Stellite 6 for high-temperature, abrasive, or cycling service above 500°F where fire-safe certification is required and ambient leakage tolerance is acceptable. Multi-layer composite when you need both fire-safe and bubble-tight at ambient in the same valve.

A: Valve ends are beveled per ASME B16.25. Welding procedures, filler materials, and PWHT must comply with ASME B31.3 or applicable project code. WCB uses standard carbon steel procedures. F316 requires stainless filler and controlled heat input.

A: Yes. Butt-welded ends are preferred for buried and submerged piping—no gaskets to leak, no bolts to corrode. Specify external coatings per project requirements for the body material in that environment.