... 4 GB,JIS,ISO,ASTM,BS,DIN the black carbon steel pipe is widely use in conveyor belt transmission ... use in construction,goods shelf,steel sheds,truck manufactruing,road construction,fence manufacturing,gate manufacturing,workhop manufacturing etc. ItemSpecificationSize ... construction,fence,structural tube,window section and other parts ,frame, shelf,etc Executive StandardGB-13793-1992 BS1387 ASTM A53 ...