union 又叫活接头或由任。连接两管子的管件，可不动管子而将两管分开，便于检修。
管接头 hose nippler ; pipe fittings
软管接头 hose connection ; hose coupler ; hose coupling ; hose fitting
异径管接头 reducing coupling ; reducing socket ; reducing piece
套管接箍 [油气] Casing Coupling ; casing collar ; [油气] casing joint
套管接头 sleeve joint ; muff joint ; pipe coupling ; socket joint
焊接式管接头 Weld fittings ; welded fitting ; socket-welding fitting ; welded pipe joint
进油管接头 Inlet connector ; Inlet nipple ; oil suction pipe joint
四通管接头 union cross ; cross pipe ; four way pipe fitting ; [机] four-way union
卡套式管接头 Bite type fittings ; ferrule fitting ; eremeto-type fitting
因此，在调节管接螺母的紧固度时，阀座对球体的压力就一直存在着。
Thus, by adjusting the tightness of the union nut, the squeeze of the seats against the ball would be maintained.
除非完全平行或垂直于阀体，或者不要在任何位置用手调整管接螺母。
Do not adjust the union nut with the handle in any position other than fully parallel or perpendicular to the body.
在安装期间，手动紧固管接螺母用来压紧Chemtrol阀门的表面密封。
Upon installation, a hand-tightened union nut serves to compress the face-seal of a Chemtrol valve.
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