Analysis of the make-up and break-out behaviour of API line pipe threaded connections

In this study a series finite element analyses on API Line Pipe conical threaded pipe connections is carried out to quantify the influence of connection’s geometry and contact properties on the stress distribution resulting from make-up and the load distribution over the threads when an external load is applied. In the assembled pipes, small sliding of the thread contact surfaces is still possible due to elastic deformation under external loads. To validate the results of the finite element analyses and to obtain a value for the coefficient of friction for the thread surfaces, experimental make-up and break-out tests were carried out. In an additional fatigue test, the sliding of the threads caused fretting fatigue damage