... 2. HDPE protection pipes. 3.sub duct. 4.optic cable protection pipe. 5. HDPE conduit HDPE silicon core pipe is ... product is widely used in protecting sleeve pipe for optical cable of express way, rail way, telecom communication system, ... core pipe can reach over 2000 meters, because of few joints, it can be laid in succession in long distance, ... . include 21,25,32,40,50,60mm. optic cable protection pipes