... pipes used in steel construction. 1) Dimentions: 30*30mm-800*800mm, Thickness: 3-40mm Length: <13mBig size Square steel tube with good quality ... ) Material: Q235, Q345, 20#, ST37, ST44, ST52, ASTM A53, ASTM A106,STKR4907) Plain or beveled ends Seamless Square Steel Pipe used in construction ...