接管 coupling
收缩管 constricted tube
异径内承插管 reducing coupling
异径外承插管 double male reduction
异径套管 reducing bushing
螺纹接管 nipple
阀 valve
截止阀 stop valve
止回阀 check valve
角阀 angle valve
球阀 ball type valve，ball valve
闸阀 gate valve
操作阀 service valve