... professional manufacturer of siphon,drainage,ground source. Black HDPE pipe is good for anti-UV, anti-aging, anti- ... using.• polyethylene pipe can be weld,fittings and pipes into one,without the possibility of joint leakage,which will ... reliable.• Good flexibility,small tube can be winding,pipe can be meandering along the ditch.resist the geological ... ,the same layer drainage system. Double U pipe fitting