Double-wall roll-welded steel tube is suitable to be used in any normal industry, especially is ideal tube in condensator,evaporator exhaust pipe , refrigerating equipment,automoblie fuel oil pipe.and brake-pipe, electrical heating pipe,refrigeration system pipe and compressor pipe. The specifications of tubes with 0.7mm wall thickness are as the follows : Dia4.76,Dia5.0,Dia6.0,Dia6.35,Dia8.0,Dia9.52,Dia10.0,Dia12.0,Dia15.0,Dia16.0. The specifications of tubes with 1.0mm wall thickness are as the follows : Dia8.0,Dia10.0,Dia12.0 ,Dia15.0,Dia16.0. Double-wall roll-welded steel tube has great corrosion resistance by surface treatment like:galvanized outer wall, chrome acid rainbow passivation;galvanized in outer wall,chrome acidolive green passivation; galvanized in outer wall and chrome acid olived green passivation,coated PVF;hot-dip galvanized or plumbum-tutania plating outer wall. Out Diameter(mm): 10 Permissible Diameter(mm): 0.05 Wall Thickness(mm): 10 Permissible Deriation(mm): 0.12 weight (G/M): 220 Pressure Ressitance(Mpa): 58