以往采暖回水管过门时 ,下垂管段一般均敷设在小地沟内 ,这样由于管道穿沟盖板处难以严密 ,使沟内积存垃圾 ,有的还泡水 ,不但影响室内卫生 ,还可能造成冻结事故。笔者早在 60年代曾将下垂管段采取直埋敷设 ,事后未出现任何不良后果 (见右图 )。埋地管段采用焊接连接 ,并在水流 In the past, when the heating return pipe passed through the gate, the sagging pipe section was generally laid in a small trench. This made it difficult to tightly cover the trench cover plate, trapped in the ditch, and sometimes soaked in water. This not only affected indoor hygiene, but also caused freezing accidents. . In the early 1960s, the author used direct burial of sagging pipe and no adverse consequences afterwards (see right figure). Buried pipe sections are welded and connected to the water stream