Research Onsealing And Optimal Design Of Press-fitting Connector Of Submarine Pipeline

Submarine pipeline is an important channel of oil and gas transportation,which is the key components for the offshore oil and gas resources exploitation system.In the complex environment under the sea,pipeline inevitable failure would happen,the timely and effective completion of pipeline damage repair can guarantee the normal production,can also reduce environmental pollution from oil and gas leak.Press-fitting mechanical connector is used for submarine pipeline emergency repair,when pipeline damaged part is replaced by a new pipeline,the connector can quickly realize the connection between the two section of the pipeline.This paper mainly study the sealing mechanism and the multi-objective optimization design of the press-fitting connector for oil and gas transportation under the sea.The structure of the connector has important influence to the sealing performance.First of all,on the basis of the 8 inch press-fitting mechanical connector,it design the overall structural of 12 inch connector,improve the structure of double sealing ring,and analyze the influence of structure size of press-fitting mechanical connector in sealing performance.Second,it study the sealing mechanism of press-fitting mechanical connector in microscopic scales,based on the related characteristics of the contact between two metal rough surfaces,it put forward the mathematicalmodel of the elastic-plastic deformation and plastic deformation of asperity in the process of contact,set up a statistical model of elastic-plastic contact betweenrough surfaces,deduce the mathematical expression between the average separation distance and the actual contact area and contact pressure,on this basis,it further study on the relationship between contact area with metal static seal leakage rate.Finally it obtain the sealing design criteria.After machining of metal surface in micro is uneven,in this paper,by using the FFT method to simulate the metal mechanical processing surface,based on the generated rough surface,it numerical simulate the contact of seal interface by using finite element method,study the relationship between the contact load and real contact area as well as contact pressure,so as to verify the accuracy of the metal sealing design criteria.Finally according to the metal sealing design criteria,it optimize the structural parameters of press-fitting mechanical connector which apply to large submarine pipeline by using multi-objective genetic algorithm,on the premise of keeping sealing ability,further improve the reliability of sealing.