| The subsea connector,located at the end of jumper,is the key connection equipment of subsea production systems.And the core technologies of subsea connectors have long been monopolized by foreign companies,thus it is imperative to make research and development on localization of subsea connectors.In this paper,the locking mechanism of the subsea collet connector is taken as the research object.The theoretical design methods of key parameters of locking mechanism are analyzed by considering the sealing and strength constraints.(1)The mathematical contact model of the metallic lenticular sealing structure is established,the theoretical relationships between the sealing structure design parameters and the contact width,contact pressure and contact load are deduced,and the design principles,which meet the requirements for sealing and strength,are built up.The theoretical relationships established in this paper are verified by Finite Element Method(FEM).In this way,the theoretical design method for the metallic sealing structure of the subsea connector is developed.The relationships between different structural design parameters are further discussed.(2)Based on the GB150 and ASME VIII-3 standard,the key parameters of thick-wall Hubs bearing high pressure are designed.Considering the shortcomings of standard design methods,a design method based on stress analysis is developed.In this method,the hub structure is simplified as two parts,i.e.the thick-wall cylinders and hollow annular plate.The mechanics analysis models are established for the thick-wall cylinders and hollow annular plate under the action of axisymmetric edge moment and edge shear force,and the analytical solutions of internal forces,displacements,rotation angles,and stress components are obtained through the continuity conditions.A case study is carried out,in which the calculation program codes are given for different design methods and a comparative analysis for characteristics of these methods are carried out.(3)The load transmitting relationships between different components of the locking mechanism are established,and the theoretical relation expressions of the preload with structural design parameters and sealing parameters are put forward,which makes it possible to directly calculate the preload through the given structural design parameters.In order to reduce the preload as much as possible,the mechanical transmission efficiency ratio is regarded as the optimization objective function,constraint conditions that meet the requirements of locking and sealing performance are put forward,and an optimization design model for key parameters of the locking mechanism is developed.Considering the influence caused by uncertainty factors on structural parameters,a reliability-based design optimization model is developed,and the structural design parameters are optimized.(4)Two kinds of engineering problems existing in the installation operation of locking mechanism are analyzed in this paper.The first one is sealing failure after the locking mechanism being locked.The reasons for this problem are analyzed with the consideration of installation deviations,and the design solutions and installation control measures are put forward.The second one is the failure of installation.Risk factors that caused the installation failure are identified and analyzed systematically.A fuzzy risk analysis method is developed to make quantitative risk assessment on the installation failure events,and measures to reduce the risks of installation failures are put forward. |
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