This kind of product is made of aisi4145h alloy steel, mainly used between dill collar and dill pipe to ease transition stress concentration between dill collar and drill pipe and reduce the rate between contact area and outer wall wear. To avoid the wear and tear of dill pipe we add each 101m wide belt wear at the top and bottom of follow-welded joint and review 76m wide belt wear on the thickening of the central part of the governing body. To extend its life cycle we can also paint dpc spraying anti-corrosion coatings in the dill pipe wall. If order or inquiry please offer: 18pshoulder chamfer 90pshoulder chamfer It need to be discussed