erw steel pipe GB/T3091-2008 ASTM A53 ,BS1387 OD:20-219mm Thickness:0 ... , Q235,Q345 Product nameerw steel pipe GB/T3091-2008 ASTM A53 ,BS1387Out diameter10mm-325mmWall Thickness0.7-12mmStandardGB/T3091 ... -2008 ASTM A53 ,BS1387Quality gradeFirst gradeTolerence of OD±0. ... under the ISO9000. erw steel pipe GB/T3091-2008 ASTM A53 ,BS1387