... : Q235, Q345, 20#, ST37, ST44, ST52, ASTM A53, ASTM A106 Rectangular hollow section:1.Item: square pipe2.Standard: GB, ASTM, BS ... . Process methodCold drown, high frequency welded3. MaterialQ195---Q2354. Size a. side length15mm--600mm b. W.T.0.3mm--13.5mm5. LengthMax ...