Triple Offset Cryogenic Butterfly Valve with Extended Stem – Low-Temperature Service

The triple‑eccentric cryogenic extended‑stem butterfly valve is a high‑performance metal‑seated butterfly valve specially engineered for low‑temperature and cryogenic service. It adopts triple‑offset geometry and extended‑stem design, mainly consisting of valve body, disc, stem, metal sealing system and actuation device.

Thanks to the triple‑offset structure, the disc moves with nearly no or minimal friction against the seat during opening and closing cycles. It effectively reduces wear on sealing surfaces and improves service life as well as sealing reliability of the valve.

The extended stem increases the distance between cryogenic medium and the stuffing box / actuator assembly. It minimizes cold‑loss transfer to stem packing and operating mechanism, lowers risks of frost formation and freezing, and ensures stable valve operation under cryogenic conditions.

The valve opens and closes by driving the disc to rotate around an offset axis via the stem. Its core triple‑offset geometry defines the operating logic of the valve:

• 1st Offset (Axial Offset): The stem axis is offset from the central line of the disc (center of sealing face), ensuring the disc lifts off the seat rapidly at the initial stage of valve opening.
• 2nd Offset (Radial Offset): The stem axis is offset relative to the centerline of the valve body bore, allowing the disc to clear the seat inner ring during rotation and minimizing frictional travel.
• 3rd Offset (Cone‑Angle Offset): The axis of the conical sealing surface forms an angle with the pipeline centerline, creating a conical‑elliptical sealing profile.

Opening Sequence: The actuator rotates the stem. Owing to the triple‑offset geometry, the disc sealing face lifts off from the seat at the very beginning of rotation. Virtually no friction is generated throughout the full 90‑degree travel until the valve is fully open for unobstructed medium flow.

Closing Sequence: The stem rotates in reverse direction. As the disc approaches the seat, it engages gradually along a dedicated conical path. Torque transmitted via the stem wedges the disc into the seat to generate sufficient contact pressure for torque‑actuated sealing, rather than relying on seat deformation. This design delivers higher specific sealing pressure under elevated medium pressure, achieving more reliable sealing performance.