square steel pipe can be used in construction structure ,machinery ,container ,hall structure ,airport structure ,shipbuilding Product:square steel pipeMaterial:Q235,Q345,20#,ST37,ST44,ST52 and so onSpecification ... *30-600*600 the wall thickness between :2-25mmsquare steel pipe can be used in construction structure ,machinery ,container ,hall structure ,airport structure ,shipbuilding500mm*500mm ...