... wall thickness:3-30mm Material: Q195,Q235B,Q345B Products NameSquare hollow tubeSizeDiameter30*30-600*600Thickness3-25Length6-12mMaterialsQ235,Q345,20#,ST37,ST44,ST52,ASTM ... A53, ASTM A106,STKR 490 and so on StandardsJIS G3466 ... , DIN EN10210, DIN EN10219, ASTM A500, GB/T3094-2000,GB/T6728-2002Useconstruction structure, ...