Finite Element Simulation of Jump-Out Behavior of Threaded Pipe Joints Used in Oil-Producing Wells

High tensile strength is one of the most important requirements for threaded pipe joints used in oil or gas-producing wells. If an excessively large tensile load is applied to the joints, a jump-out phenomenon of the pipe from the coupling occurs. The jump-out phenomenon depends largely on the thread profile, the nonlinear material properties and the contact condition at threads. In this paper, as a fundamental study, the jump-out behavior of a one-ring thread model was experimentally investigated and the FEM simulation was conducted considering the material nonlinearity and the contact condition at threads. Here, the penalty function method was applied as a technique of introducing contact condition into a large deformation elasto-plastic FEM code CAPS, which has been developed by the authors. A jump-out test of actual 473.1-mm-(18-5/8-in-) dia joint was carried out, and based on the experimental results, one criterion was proposed for the slide out of helicoidal thread in FEM simulation. As a result, the present FEM simulation method can be applied to the analysis of the jump-out phenomenon of the threaded joint.