... ,JIS,ISO,ASTM,BS,DIN the black carbon steel pipe is widely use in conveyor belt transmission, ... have a trip. you know the rectangular steel pipe is world wide use in construction,goods shelf ... have a trip. you know the rectangular steel pipe is world wide use in construction,goods shelf ... T14291-1992Steel gradeQ195,Q195L,Q235 Q460 Q345 and so on Surfacelightly oil , include black, bright and pre-galvanized ...