Diaphragm - weld packings and weld ring seals for flange connections 法兰连接用隔板焊接密封件和焊接环形密封件
2.
Pipes and fittings of unplasticized poly vinyl chloride with ring seal socket for non pressure underground drainage and sewerage - part 3 : quality control and installation 非压力地下排水和污水排放用带环形密封承口的硬聚氯