Drill is an essential part of the drill drill collars manufacturers string, which is mainly used to transfer torque and transporting drilling fluid. Active drill pipe body and joints are connected together using welded method. In order to increase the strength of the joints, pipe welding ends body part is thick, thick form of internal upset, outside the thick, thick inside and outside the three.
     Narrowing the inner diameter of the pipe ends to increase the inner thickened wall thickness, which is consistent with the outer diameter of the drill pipe, the outer diameter of the joint is not too large, while the well rotary joint in contact with the borehole wall is small, wear are more small, but because the inner diameter of the thickened portion of smaller diameter than the tubular body, to increase the flow resistance of the drilling cycle.
     Inner diameter of the external upset drill pipe is the same, but the outside diameter of the tube ends of the increase, the outer diameter larger than the outer diameter of the tool joint drill with the size of the joint, increases when the well rotary joint on the wall contact friction, easy to wear; Since this is consistent with the inner diameter hole opener drilling of the drill pipe inner diameter, the cycle of drilling fluid flow with less resistance.
     Inner and outer thickened drill pipe, the inner diameter is reduced at both ends of the tubular body, the outer diameter is increased to increase the wall thickness of the ends of the tubular body. Drill this structure combines the advantages of these two structures the drill pipe.