比较先进的蝶阀是三偏心金属硬密封蝶阀，阀体和阀座为连体构件，阀座密封表面层堆焊耐温、耐蚀合金材料。多层软叠式密封圈固定在阀板上，这种蝶阀与传统蝶阀相比具有耐高温，操作轻便，启闭无磨擦，关闭时随着传动机构的力矩增大来补偿密封，提高了蝶阀的密封性能及延长使用寿命的优点。
技术指标 Technical indicators
1.口径：4″-80″ 1.size: 4″-80″
2.压力：150LB-900LB 2. Pressure: 150LB-900LB
3.阀体材质： 3. Body material
碳素钢 -50℃-425℃ Carbon steel -50℃-425℃
合金钢 -50℃-610℃ Alloy steel -50℃-610℃
不锈钢 -50℃-700℃ Stainless steel -50℃-700℃
应用范围 Range of application：
1.石化厂：盐水，二氧化碳蒸汽、丙烯厂、蒸汽系统、氧气系统、氢气，丙烷气、火焰入口和Maniford隔离、乙烯厂、PSA和分析筛、乙烯裂化装置、焦化厂。
Petrochemical plants:brine,CO2 vapor; propylene plants, steam service, oxygen service, hydrogen gas; propane gas, flare inlet and maniford isolation; ethylene plants; PSA & molecular sieves; ethylene crackers; coking plant
2.火力发电：泵隔离、冷凝器冷却、泵和蒸汽抽取隔离、热交换器，冷凝器冷却隔离
Fossil power plants: pump isolation; condenser cooling; pump and steam extraction isolation; heat exchanger, condenser cooling isolation
3.低温：所有液态气体、液化和天然气系统、油田回收系统、气化厂和储存设备、液化天然气运输系统
Cryogenics: all liquid gases; liquid and natural gas service; oil field recovery system; gasification plants and storage; LNG ship’s service
4.纸浆和造纸：蒸汽隔离，锅炉水、绿&红和黑液、氧气管道、石灰和泥浆
Pulp and paper: steam isolation, boiler water; green&red and black liquors; oxygen lines; lime and mud
5.核电厂：容器隔离、盐水系统、堆心喷淋系统、泵隔离
Nuclear power plants: containment isolation: saltwater service; core spray systems; pump isolation
6.石油炼制：储油库隔离、供气阀、脱硫系统和废气处理器、火炬气&氢气&酸气隔离、热裂气、催化裂化器装置
Petroleum refining: oil storage isolation, steam supply valves, desulphurization systems and tall gas treaters; flare gas hydrogen, sour gas isolation; hot cracking gas; catalytic cracker units;
工作原理
WT三重偏心蝶阀具有双向无气泡紧密关闭性能。这种几何形状保证阀笼密封只是在关闭位置时才与阀体阀座接触，因此不会产生摩擦或磨损，并且产生一种扭矩使得弹性密封具有足够的“焊接”功能，确保密封接触的均匀一致性。
三偏心几何形状
偏心1 阀轴位于阀座轴后面，使得密封能够完全紧密环绕接触整个阀座。
偏心2 阀轴中心线偏离管道和阀门中心线，这就免受阀门开启和关闭的干扰。
偏心3 阀座锥体轴偏离阀轴中心线，这样可以在关闭和开启过程中消除摩擦作用，并且实现环绕整个阀座的均匀一致的压缩密封效果。
Principle of operation
Welland&Tuxhorn[W&T] triple offset butterfly valve provides a bl-dlrectional bubble tight shut-off. This geometry ensures that the disc seal contacts the body seat only at the final shut-off position without rubbing or galling, providing a torque generated resilient seal with sufficient “wedging:” to ensures a uniform seal contact.
The triple offset geometry
Offset1 the shaft is offset behind the seat axis to allow complete sealing contact around the entire seat.
Offset2 the shaft centerline is offset from the pipe and valve which provides interference free opening and closing of the valve.
Offset3 the seat cone axis is offset from the shaft centerline to eliminate friction during closing and opening and to achieve uniform compressive sealing around the entire seat.
