ERW steel pipe OD:21.3mm-610mm Wall thickness:1.5mm-18mm Standard:API 5L,ASTM A53,ASTM A252,EN10217 Steel grade: B,X42,X46...X60;Gr.1,Gr.2,Gr.3;S235,S355;Q235B,Q345B Certificate: API 5L,API 5CT,CE,ISO9000