Static metal sealing mechanism of a subsea pipeline mechanical connector

The static metal sealing mechanism is essential for the structural design of subsea pipeline mechanical connector. By analyzing the sealing mechanism and contact pressure on sealing face, the critical condition of the seal is obtained. Based on the superposition theorem of elasticity, the formula of critical mean contact pressure ensuring seal is deduced. The finite element analysis result of critical mean contact pressure agrees with the analysis result very well and the critical mean contact pressure decreases with the increase in pipeline wall thickness and sealing width; however, the radius of pipeline has less influence on it. The critical mean contact pressure of 8-in subsea pipeline mechanical connector is 223.34 MPa and subsea pipeline mechanical connector is designed with ANSYS. The internal pressure experiments indicate that the sealing performance of final designed subsea pipeline mechanical connectors is higher than the design pressure of 4.5 MPa and all the initial designed ones cannot seal up to 4.5 MPa. By observing the sealing indentation on pipeline surface, when the mean contact pressure is higher than the critical mean contact pressure and the contact pressure variance is smaller, a full contact is seen to form a seal. Finally, the vibration experiments prove that the number of vibration is more than 107 and final designed subsea pipeline mechanical connector meets the experiment specification.