Thanks to the three-layer co-extrusion die with spiral grooved core rod for option and the advanced technological prescription,the line is designed to produce pvc middle layer expanded pipe or pvc middle layer expanded pipe with screw-thread inwall .this kind of pipe features:lower density 0.9-1(while traditional pipe about 1.4)sound-proof,when used as drain-pipe water flow against the screw-thread inwall downwards ,which solves the problem of noise .it is identified that pvc expanded pipe with screw-thread inwall can lower the noise for 5 to 7 DB than pvc expanded pipe,and 10 to 15 DB than traditional pvc pipe ,and it is the most ideal drain pipe for building up to now
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