Metal Sealing Mechanism And Structural Reliability Analysis Of Subsea Clamp Connectors Under Multi-factor Coupling

As a common connection system for offshore oil and gas underwater development,the underwater clamp connector has a complex structure and is subjected to harsh external loads and the coupling of internal high temperature and high pressure oil and gas media,which will cause oil and gas leakage and Marine pollution once damaged.Therefore,it is of great practical significance for the safety of underwater oil and gas development projects to master the metal sealing mechanism of underwater clamped connector lens,establish the reliability evaluation method of underwater clamped connector structure under multi-factor coupling,and form a multi-objective collaborative optimization design technology of underwater clamped connector structure.In this paper,the structural characteristics and working principle of underwater clamp connectors are analyzed,and the main failure modes are determined as seal and strength failure,and the criterion of seal and strength failure is defined.On this basis,the theoretical models of sealing parameters such as sealing width,contact pressure and strength parameters such as stress component were established respectively for the metal lens sealing structure of underwater clamp connectors under preload and operating conditions.Then,select the metal seal ring and flange structure of the underwater clamp connector to establish the physical model,carry out the sealing performance model test to study and analyze the typical position of the mechanical parameters and seal width and other parameters.In this paper,a reliability evaluation method for underwater clamped connectors based on multiple response surfaces is developed considering the synergic effects of structural characteristics,internal fluid pressure and temperature,external load transfer and other factors.For a certain type of underwater clamp connector used in the South China Sea,the structural size,temperature and internal pressure of the flange and seal ring of the underwater clamp connector were selected as random variables,and the maximum equivalent stress,maximum contact pressure and maximum penetration were selected as response surfaces.By means of Latin hypercube sampling design and least square method fitting,the function expressions of each response surface are obtained.Based on kernel density estimation method and stress intensity interference theory,the comprehensive reliability of the underwater clamp connector is 98.64%,which meets the application requirements.In view of the over-optimization problem caused by the single objective optimization of the complex structure of underwater clamped connectors,this paper takes the minimum maximum equivalent stress of the structure,the maximum contact pressure and the lightest mass as the objective function,selects the multi-island genetic algorithm as the optimization algorithm,and carries out the multi-objective structural optimization design based on multiple response surfaces combined with the underwater clamped connectors studied in this paper.The multi-objective optimization scheme can better take into account the relationship between the three responses,so that the design parameters of the underwater clamp connector can achieve the optimal design.In this paper,a theoretical model between sealing parameters and strength parameters of underwater clamp connectors is established,a reliability evaluation method of underwater clamp connectors based on multiple response surfaces is created,and a multi-objective optimization design process based on multiple response surfaces is formed.Relevant research results provide a more reliable connector design evaluation method for the safe development of deep-sea oil and gas resources in China.It has laid a solid technical foundation for China to build a maritime power.