Finite Element Analysis of Contact Stress in a Full-metallic Pipe Joint for Hydrogen Pipelines

Hydrogen gas has been widely recognized as an environmentally clean and renewable energy fuel, and it provides a way to reduce greenhouse gas and air pollution emission. A great deal of effort has been made to develop new techniques in the field of hydrogen energy, including hydrogen production, storage, and infrastructure. Recently a metallic gasket, which is made of type 316L stainless steel, has been developed for hydrogen pipelines and pressure vessels. Contact stress analysis is important to verify structural strength of pipe joints using this gasket and to determine service parameters in order to achieve sufficient sealing performance. This paper reports a preliminary study on contact stress analysis of a full-metallic bolted flange joint with the metallic gasket in bolt-up conditions. Because of shape and size of the contact interface in this pipe joint, direct measurement of the contact stress is difficult. Therefore, contact stress analyses have been performed numerically using a three-dimensional (3D) finite element method. The analytical object is a bolted flange joint for stainless steel pipes (Nominal size: 38 mm). 3D solid model was made up with CAD modeling software, Pro/Engineer. Then, analyses were performed in a commercial finite element analysis environment, ANSYS Workbench. The numerical results indicate a localized distribution of contact stress on the gasket’s surface. In addition, a wellcontrolled bolt pretension is crucial for this gasket to prevent plastic deformation in the materials. Key–Words: Metallic gasket, pipe joint, hydrogen pipelines, contact stress analyses, finite element model (FEM).