... ,quick delivery constrution use hot dip galvanized square and rectangular steel pipe/SHS/RHS 1. Outer diameter:20*20-400*400mm2 ... 1:2006, EN10219-2:2006 JISG3466-889. Application: square steel pipe are widely used in machine-building, construction, metallurgy, automobile ... in many industries, for instance, steel construction project, machinery making and shipbuilding.structural square tube OD(mm)WT(mm) ...