Analysis Of Contact Sealing Performance Of The Scalable Hinged Flexible Pipe Joint

As a new type of pipeline connection, the Scalable Hinged Flexible Joint (SHFJ) is usually composed of a metal sphere inner sleeve, a metal sphere outer sleeve, two sealing rings of rubbers and pipelines, and presents good performance of pipeline connection. Due to its unique properties, for example, the flexibility in extension, contraction and rotation, and the ability of withstanding axial loads, radial loads and deflecting action, SHFJs have been widely used in various of pipeline transportation systems, such as the systems for tap water, oil and gas transportation.In pipeline transportation systems, the sealing property of pipeline joints plays a key role; therefore the analysis of the sealing property of a SFHJ is an important step for its design. In order to motivate the study of sealing performance of the SHFJ, the research status in the related field is reviewed first; then the structure details of the SHFJ studied is determined. On the basis of analyzing the characteristics of connection and sealing of the joint, the types, elements and pairs of contact as well as the constitutive equation used to sealing rings of rubbers are determined for the finite element analysis, further the finite element formula for solving contact problems are derived. Following the steps of structure-designing, meshing, loading and defining the boundary conditions, solving and post-processing, the finite element analyses of the SFHJ are conducted under two loading conditions, i.e. only the initial interference included and the hydrostatic pressure applied additionally. In order to study the stress level and sealing property of the joint, the distributions of von Mises stress and contact pressure in the contact zones under the two loading conditions are presented, and a series of coMParisons between the results corresponding to the two loading conditions is conducted. The results show that the maxima of von Mises stress in the joint arise respectively in the middle band of the surface of the sphere outer sleeve contacting with rubber ring 1, the middle band of the surface of the sphere inner sleeve and the inner surface of the pipe contacting the rubber ring 2. The distributions of the contact pressure are approximately symmetrical and perpendicular to the contact surfaces; CoMParing the contact pressures calculated under the two loading conditions, it can be found that the contact pressures are larger than the hydrostatic pressure, so it can be deduced qualitatively that the joint has an enough ability of sealing, the results obtained provide can be used as a numerical basis for the design of the joint.