1 high tention and good quality 2 black carbon steel pipe manufacture 3 widely use in many ways 4 GB,JIS, ... ISO,ASTM,BS,DIN the black carbon steel pipe is widely use in conveyor belt transmission,machine rotary drum ... Q345 and so on Surfacelightly oil , include black, bright and pre-galvanized End cleanThickness toleranceto your standard or to ASTM,Gbstandard requirementPackingBy ...