composite pipe: 1) high-frequency welded 2) outer diameter:21.3-219.1 3) steel grade:Q195,Q235,Q345 4) standard: ASTM,EN,BS ... :1) high-frequency welded2) outer diameter:21.3-219.13) steel grade:Q195,Q235,Q3454) standard: ASTM,EN,BS,GB.Details ... .55/3.75/3.85/4.0/4.25*6m Steel-Plastic Composite Pipe