... *600mm. 5.Surface:Black painting or oiled steel square tube 1)Thickness:0.5-30mm2)Size(dia ... St52 St42 St35 API155Product CategoryMetallurgy, Mineral & EnergyTechniqueWelded,ERW Cold Rolled,Hot RolledSurfaceBared, Galvanized, Black Oiled,Or ... welded steel pipe manufacturing group. We have cooperated with Bao steel, Wu yang steel, TPCO, Baotou steel, Shou gang Jin tang Steel, An gang Steel, Daye Steel ...