GB/T 18477.3-2009

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

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