... in construction structure ,machinery ,container ,hall structure ,airport structure ,shipbuilding Product:square steel pipeMaterial:Q235,Q345,20#,ST37,ST44,ST52 and so onSpecification ... :30*30-600*600 the wall thickness between :2-25mmsquare steel pipe can be used in construction structure ,machinery ,container ,hall ... 20mm*20mm*2mm~4mm160mm*160mm*5mm~16mm150mm*150mm*5mm~14mm square steel pipe