inlet union nut

例句：

1. 1. The engineer carefully removed the inlet union nut to inspect the sealing surface.
   工程师小心翼翼地取下入口联合螺母，检查密封表面。
2. 2. During installation, the inlet union nut was placed over the valve stem and tightened securely.
   安装过程中，入口联合螺母被放置在阀杆上并牢固地拧紧。
3. 3. The inlet union nut is a critical component that must be replaced when the valve fails.
   入口联合螺母是阀门失效时必须更换的关键部件。