GB/T 18477.3-2009 埋地排水用硬聚氯乙烯(PVC-U)结构壁管道系统 第3部分:双层轴向中空壁管材 Unplasticized polyvinyl chloride (PVC-U) structure wall pipeline system for underground soil waste and drainage—Part 3:Bilayer and hollow-wall construction with axial hollow pipes
Unplasticized polyvinyl chloride (PVC-U) structure wall pipeline system for underground soil waste and drainage—Part 3:Bilayer and hollow-wall construction with axial hollow pipes