The contact mechanics model of the metal lens-type sealing gasket is established on the basis of Hertz theory on the macroscopical scale in this paper. The relationship among sealing width, contact pressure, and preload is solved. Based on the structural characteristics of the subsea collet connector, the self-locking characteristics are analyzed to determine the gain coefficient of the sealing structure for the loading thrust. On the microscopic scale, the contact characteristics of the turning lens-type sealing gasket and the hub structure are analyzed by the equivalent replacement of the peak cut coefficient of the one-dimensional sinusoidal wave. The influence of different leakage forms on sealing performance is discussed from both radial and circumferential leakage, and the leakage rate of the lens-type sealing structure is calculated. The hydrostatic pressure experiment of the subsea collet connector with lens-type sealing gasket is carried out, and the correctness of the theoretical analysis is verified from the results of the pressure maintaining, sealing width measurement, and preload conversion.

No abstract

Underwater oil and gas pipelines are prone to alignment differences and angle offsets during docking, and the spherical flange connector can address this problem. Its main function is to enable compensation of the different angles of the pipeline during docking and to apply a non-standard spherical sealing structure using O-rings to the connection. In this paper, the study of a spherical sealing structure using O-rings was based on a spherical structural model of the connector. The Mooney–Rivlin constitutive equation and material parameters of the O-ring were determined according to nonlinear theory. The structure of the non-standard spherical sealing groove was designed and analysed with reference to the standard sealing groove, the calculation expression of the spherical groove specific size was deduced, and the width and depth of the groove were determined. A finite element analysis of the non-standard O-ring sealing structure was carried out using ANSYS Workbench software; the effects of different pressures and compression ratios on the O-ring sealing performance were analysed and studied in terms of von Mises stress, contact pressure and contact width of different contact surfaces so as to determine a more reasonable compression ratio in the sealing structure. Finally, the theoretical analysis of the non-standard spherical sealing structure using O-rings was validated by testing, and it was proven that it could maintain a good seal under high pressure.

No abstract

To establish an accurate real-time visual reality system for offshore hoisting operations, the “Offshore Oil 201” crane ship was employed as a background, and a mathematical model for hoisting operations was created with regard to the influence of ocean environment, the dynamic positioning system of the crane ship, the ballasting system based on the ship’s six degree of freedom (DOF) real-time feedback, and the manipulation of the control system. An interactive three-dimensional virtual scene was constructed with the virtual reality technique, multi-channel data interaction, real-time numerical calculation, and semi-physical simulation in order to realize the immersive feeling of the scenes. Bliss approximate integration was used to solve the mathematical model of the hoisting system and the real-time data interaction of the simulation system was realized on the basis of the accurate solution. The simulation results show that the simulation system can solve the time response of the hoisting system with good calculation accuracy. The preview of the construction project of the offshore hoisting operation can be implemented by the simulation system to investigate the key parameters and hoisting process, which will effectively reduce the risk of offshore hoisting operations and enhance the safety of the offshore engineering operations. The problem of high cost of staffs’ training has been solved, and the simulation system has both accuracy and instantaneity, the whole process of offshore hoisting is demonstrated with the highest authenticity.