... trip. you know the rectangular steel pipe is world wide use in construction,goods shelf,steel sheds,truck manufactruing,road construction, ... trip. you know the rectangular steel pipe is world wide use in construction,goods shelf,steel sheds,truck manufactruing,road construction, ... ,structural tube,window section and other parts ,frame, shelf,etc Executive StandardGB-13793-1992 BS1387 ASTM A53 ASTM GB ...