Standard:GB/T3091-2008 ASTM A53 BS1387 ASTM A500 1) W. T: 0.8mm to 8.5 mm 2) O. ... welded round steel pipes :Low Pressure Fluid Transmission Pipe:GB/T 3091 Q195,Q215,Q235, Q295, Q345, 10#,20#, ... 16Mn etc.GB/T 13793 Q195,Q215,Q235, Q295, Q345, 10#,20#, ... P265TRpre-galvanized round steel pipe Erw Round Structural steel pipesGB/T 13793 Q195,Q215,Q235, Q295, Q345, 10#,20 ...