Structural behavior of threaded connections for sandwich pipes under make-up torque, external pressure, and axial load

The concept of sandwich pipes for subsea applications has been studied independently of an available connection to joint the pipe segments. Therefore, it is necessary to propose and study the design of a pipe segment connection to build a continuous sandwich pipeline. The reported research work suggests using threaded connections of integral type with square teeth and metal-to-metal sealing. The threaded connector is analyzed by a two-dimensional numerical model using nonlinear finite elements to obtain both contact stress and maximum tension under make-up torque, external pressure, and axial loads. The make-up torque is applied through radial interference for different tightening torques. The results indicate that the threaded connector is a feasible solution for the sandwich pipe joint, especially for the watertight requirement under combined loads.