Triple Offset Butterfly Valves
Triple-offset butterfly valves (TOV) are quarter-turn metal-seated valves that add a third, conical offset to the two eccentric offsets of a high-performance valve. The seat and disc sealing surfaces are machined as matching cones, so the disc makes contact with the metal seat only at the very end of the stroke, with no rubbing during travel — a torque-seated, friction-free, cam action. This geometry delivers bidirectional bubble-tight (zero-leakage) shut-off with an all-metal seat, combining the tight sealing usually associated with a gate or ball valve with the compactness of a butterfly, which is why TOVs are specified for high-temperature, fire-safe, cryogenic and severe isolation service.
Triple-offset valves are built to API 609 Category B with ASME B16.34 governing the pressure-temperature rating and zero-leakage metal-seat sealing, tested to API 598 (often to the stricter zero-bubble acceptance). They are commonly offered ASME 150, 300 and 600 (PN 16-100), with higher classes on engineered designs, in sizes from about 3" up to 60"+ in wafer, lugged, double-flanged and butt-weld patterns, over a temperature range typically spanning cryogenic (around -196 degC) to roughly 600 degC depending on seat construction.
Bodies are usually WCB / A216 carbon or CF8M (A351 SS316), with duplex, super-duplex, Inconel or Monel for corrosive and sour duty. The laminated seal ring is typically a stainless-and-graphite (or PTFE) laminate retained on the disc, sealing against a stellite-overlaid metal seat for durability and fire integrity. Shafts are blow-out-proof in SS17-4PH, duplex or similar.
TOVs are actuated by gear, pneumatic spring-return or double-acting, electric or hydraulic operators on ISO 5211 pads, and their inherent metal seat makes fire-safe API 607 / 6FA construction straightforward where ESD or hydrocarbon duty requires it. API 641 / ISO 15848 fugitive-emission packing can be added for emission-regulated service.
Himalay's MSME partners manufacture triple-offset metal-seated butterfly valves with testing per API 598 / BS EN 12266-1 / ISO 5208, material traceability, and PED-CE (EU), SABER (Saudi Arabia), and NACE MR0175 (sour service) coordinated as part of the standard order flow.
