... Grade A/B, A53 Gr A& B, St37, 10#, 20#, 45#, etc. O.D.12-1020mm, W.T. 2-60mm. 1.Specification ... ,APISPEC5L,API5CT,ASTMA53/A106,JIS,BS1387,etc.3.Steel Grade: Q235B,Q345B,API5L Grade B,X42~X80,16Mn,20#ST37~ST52 etc ... /tubeOut diameter20-219mmWall Thickness0.9-12mmStandardGB/T3091-2001Quality gradeFirst gradeTolerence of OD±0.3mmMaterialQ195--Q235TreatmentEnds plain or beveled/Varnish coating or ...