closed pipe

例句：

1. 1. The closed pipe is used to transport liquids without leakage.
   这个封闭管道用于输送液体，没有泄漏。
2. 2.The engineer carefully inspected the closed pipe for any signs of damage.
   工程师仔细检查了封闭管道，寻找任何损坏的迹象。
3. 3.The closed pipe was installed in a remote area to prevent contamination.
   封闭管道被安装在偏远地区，以防止污染。