Analysis of the Influence of Thread Parameter Deviation on The Sealing Performance of Drill Pipe Joint Under Axial Load

Abstract

To explore the influence of the limit deviation of the thread parameters of the drill pipe joint on its sealing performance, based on the API NC38 drill pipe joint, the existence of the limit deviations of the three thread parameters of taper, side angle, and pitch is analyzed. Based on this, a total of 12 finite element models of drill pipe joints including various limit deviations and free combinations of internal and external thread limit deviations are established, and the sealing performance of different structures under the action of make-up torque and axial load is analyzed. The results show that the pitch limit deviation has the most obvious influence on the sealing performance of the drill pipe joint, and the yield failure of the contact surface is easy to occur. The existence of taper limit deviation makes the sealing performance of the drill pipe joint significantly reduced when subjected to tensile load. When the change of the limit deviation of the side angle of the internal and external thread teeth is opposite, the plastic deformation occurs locally in the drill pipe joint, which affects the sealing effect. Therefore, it is necessary to control further the tolerance range of the thread parameters of the drill pipe joint to reduce the risk of sealing failure of the drill pipe joint.