Evaluation of a Pipe-Flange Connection Replacing Fusion Welding

Joining of steel pipes and pipe flanges use today the conventional method of fusion welding, where the flange is girth-welded onto the pipe. However, fusion welding of flanges to pipes is associated with many disadvantages such as the final quality of the weld, degradation of the mechanical properties of the base pipe near the heat affected zone, defects and cracks appearing in the weld, misalignments, to mention a few. The current study proposes a novel pipe-flange connection to replace the fusion welding process of steel pipes with a method based on cold working. The method is based on that the steel pipe is inserted into the neck of the flange, in which two circumferential grooves are manufactured. An expansion tool having two teeth is entered from the open side of the connection and is expanded hydraulically such that the teeth deform the pipe and cold work it plastically into the grooves. This will provide a strong joint between the flange and pipe. In this study the performance of the connection is maximized by optimizing the design of the flange and the expansion tool.