An establishing method for worn tubing joint model and the influence of wear on stress distribution of joint sealing surface

Abstract

Wear has serious influence on the strength and tightness of tubing joint. In this paper, a new joint wear establishment method, “numerical cutting method,” was proposed and the stress distribution characteristics of sealing surface were analyzed. The three-dimensional modeling of a worn tubing joint under complex loads was successfully established and the finite element method was used to calculate the stress distribution on sealing surface. The influence of internal wear on the stress distribution of the sealing surface was analyzed and the failure mechanism of a worn tubing joint was revealed. The results showed that the contact stress of the worn part of the sealing surface decreases with increased wear depth of internal wear. When the internal wear depth reaches 3.0 mm, the maximum contact stress in the worn area decreases by 35.5% than that of the unworn joint along the axial direction and by 27.3% along the circumferential direction of sealing surface. While when the external wear reaches 3.0 mm, the stress distribution of the sealing surface is similar to that of the unworn joint. These mean that more attention should be paid to the prevention of internal wear during operation because an internal wear has more effect on the stress characteristics of the sealing surface than external wear. The sealing belt is located in the middle of the sealing surface, and the width of the sealing belt at different wear depths is roughly the same for two wear forms. This is beneficial to ensure the seal integrity of tubing joint.