API Standard Triple Offset Lug Wafer Butterfly Valve

Triple‑offset lug‑wafer butterfly valve is a high‑performance metal‑hard‑seated butterfly valve featuring triple‑offset geometry, metal‑to‑metal sealing pair and composite lug‑wafer body construction. Bolt lugs are provided on both sides of the valve body, allowing direct bolt‑through clamping between two pipeline flanges without full mating flanges, which delivers a lightweight and compact structure. Benefiting from the triple‑offset geometry, low‑friction operation during opening‑closing cycles is achieved to effectively reduce operating torque. Its metal‑to‑metal sealing pair can withstand high‑temperature and high‑pressure service conditions.

Working Principle of Triple‑Offset Lug‑Wafer Butterfly Valve：
Opening Stroke: The actuator drives the valve stem to rotate, and the disc starts turning from the closed position. Thanks to the triple‑offset design, the disc lifts rapidly off the metal sealing surface at the initial opening stage, eliminating continuous seat rubbing over the full 90‑degree rotation travel. As the disc keeps rotating, the flow passage opens progressively. When rotated to approximately 90° fully‑open position, the disc is substantially parallel to the medium flow direction, providing maximum flow area with low flow resistance and minimal pressure loss.

Closing Stroke: The actuator drives the valve stem to rotate in reverse, and the disc turns back towards the closed position. Near the final closing position, the cam‑like offset trajectory presses the disc’s metal sealing face against the seat to build sufficient sealing specific pressure. Upon full closure of the disc, the metal‑to‑metal sealing pair forms a tight seal to cut off medium flow and achieve pipeline shut‑off and isolation.