Triple Offset

Triple-offset butterfly valves are used as isolation valves in industrial piping systems where conventional concentric or double-offset designs do not meet temperature, pressure, shut-off, or fire-safe requirements. The triple-offset geometry lifts the disc away from the seat without continuous rubbing through the 90° stroke, which reduces seat wear, operating torque, and surface loading under repeated cycling.

The range includes ARI ZETRIX 016 double-flanged, ZETRIX 018 fully lugged/threaded flanged, and ZETRIX 019 butt-weld end executions, together with selected Alfa Europe and Neway versions. Available standards include DIN and ANSI patterns, with pressure ratings from PN 6 to PN 100 and ASME Class 150/300 within this category. For Neway, published ranges extend from ASME Class 150 up to 2500 and sizes from DN50 to DN4000, depending on series and construction.

Metal-seated shut-off is the main selection criterion for steam, thermal oil, hot water, industrial gases, petrochemical service, power generation, and other duties where elastomer seats are not acceptable. For ARI ZETRIX, stated features include a Stellite 21 seat, multilayer graphite/1.4462 sealing ring, leakage rate A to EN 12266-1, and a sealing temperature range from -60°C to +400°C. The allowable differential pressure follows the body pressure-temperature rating and decreases as temperature increases.

Valve selection should be based on DN, PN/Class, end connection, body material, operating temperature, differential pressure, pressure direction, required leakage class, and actuator torque. Gear operators, pneumatic, electric, and hydraulic actuators are available, with sizing based on break torque, seat load, and fail-safe requirements. For critical service, review fire-safe certification to ISO 10497 or API 607, ATEX, SIL, NACE MR0103, blow-out resistant stem design, and fugitive emission packing to EN ISO 15848-1 or TA-Luft.