Study On Resistance Of Unbonded Flexible Pipe To Radial Load

With the gradual development of oil and gas towards the deep water,more attention has been paid to offshore pipelines.Compared with traditional steel pipe,flexible pipe has stronger resistance to complex environmental loads,good adaptability,corrosion resistance and so on,so it becomes a necessary item in deep sea oil and gas development equipment.The flexible pipe is made up of multi-layer polymer layer and metal spiral layer with a complex structure.There are lots of contact and slip phenomena between layers.During the installation and operation of the hose,it will bear the crushing pressure of the installation machinery,the collapse pressure of the deep water and the high temperature and burst pressure inside or outside of the pipe.These loads challenge the ability of the tube to resist the radial load.Therefore,it is necessary to explore the ability of the flexible pipe to resist the radial load.This paper focuses on three kinds of radial load of hose: collapse load,burst load and crushing load.First,we classify and investigate the current research status.In the analysis of the collapse of the straight pipe,the carcass layer is only analyzed.The existing theoretical calculation methods of bending stiffness are arranged and calculated,and the different critical pressure values are compared and analyzed.At the same time,the ANSYS software is used to model and analyze the influence of the initial ellipticity and the interlayer friction coefficient on the critical collapse value.The calculation method of the critical collapse value of the elbow is derived by theoretical analysis and a numerical simulation method,whichis established to calculate the critical collapse value of the curved pipe.In the analysis of the burst and the crushing,the existing theoretical analysis and calculation methods are arranged and the results calculated by the numerical simulation method are compared with the theoretical results.In addition,the influence of the initial ellipticity defect and the friction coefficient on the response of the theoretical results is discussed by the numerical calculation method.