Cross Section Design And Strength Analysis Of Steel Pipe Umbilical

Umbilical cable is the key equipment in the underwater production system which is mainly composed of steel pipe for transportation of gases and liquids,electric cables for transmission power and signal,armour wire,polyester sheath and polyester filler.Steel umbilical is a kind of umbilical in which steel pipes are as the key and the main load-bearing part of umbilical.Because the internal configuration is complex and there are many nonlinear factors such as contact and friction between components of umbilical,It is difficult to carry out the mechanical analysis of umbilical.In this paper,the design of umbilical for a FPSO located at China South Sea will be presented and the strength analysis of the design will be carried out.Firstly,the author summary the research of umbilical domestic and abroad especially the application of finite element analysis in umbilical cable research and master the design of cross section and mechanics analysis method of umbilical cable.Around the South China Sea FPSO practical engineering needs design umbilical cable with failure model.Secend,the strength analysis of design through ABAQUS finite element software has been done.In account of a large number of nonlinear factors such as contact and friction which are occurred by the characteristic of non-viscous and multi-layer winding of structures and environmental load of umbilical make a local strength analysis for umbilical through ABAQUS.A full three-dimensional model is established which is fully considered the friction effect caused by contact between umbilical cable components and overcome disadvantages of model simplification.The tensile and bending analysis of the umbilical cable is carried out and strength response law of steel tube umbilical is summarized.In the process of design and analysis,the important parameters that affect the design and strength analysis of steel pipe umbilical are discussed and the sensitivity analysis of these parameters is done.Finally,with considering the coupling model and the sea state of FPSO and umbilical,the overall dynamic analysis of umbilical are carried out and the axial tension and bending force of key parts of umbilical are carried out.The structural strength of umbilical is checked,and the design of umbilical cable is evaluated.The results show that through the sensitivity analysis of umbilical cable we know the helix angle,armored dimension,boundary condition model and necking has large impact for the tensile performance of umbilical cable;The helix angle,friction coefficient and external pressure have great influence on the bending performance of umbilical cable.After checking by hydrodynamic analysis,failure phenomenon will be occurred for two designs.The research shows that,in the foundation to understand the important parameters of umbilical,through the coupled hydrodynamic analysis can be more targeted to assess the validity of the design.