Coupling, Pipe Fitting, Valves manufacturer / supplier in China, offering China Factory ASTM A536 995 997 HDPE Steel Grooved Thraded Transition Couplings, UL FM 997 Ductile Iron HDP HDPE Grooved Threaded Transition Couplings From HDPE to Steel, 997 Grooved Thread Transition HDPE Steel Coupling and so on.