Seamless steel pipes used in steel construction. 1) Dimentions: 30*30mm-800*800mm, Thickness: ... according to customers' requestsmotorcar cassis, airport structure, shipbuilding, automobile axle pipe and so on.4) Use: construction structure, machinery making, container ... , ST52, ASTM A53, ASTM A106,STKR4907) Plain or beveled ends Seamless Square Steel Pipe used in construction