Evaluation of a pipe-flange connection method based on cold work

The conventional joining method of a pipe and a flange uses welding. However, welded pipe-flange joints have the drawback with the inherent distortions and residual stresses resulting from the welding process, which can affect the mechanical integrity and performance of the flange significantly. In this study, a novel pipe-flange connection method based on cold work is evaluated using the finite element method. A weld neck flange is modified by manufacturing circumferential grooves at its internal surface and the pipe is cold worked into the grooves using a hydraulic expansion tool. The finite element model incorporates a pressure dependent friction model for the contact interaction between the tool-pipe-flange and a strain-based ductile failure locus for the pipe material accounting for ductile damage initiation during the cold work process utilizing a continuum damage mechanics approach. The finite element results show that a high load carrying capacity can be achieved for the cold work pipe-flange connection and has good potential for replacing the conventional welded joint.