Residual Strength Evaluation Of Submarine Pipelines Under Stress And Physico-chemical Coupling

Corrosion is one of the main factors of metal pipeline failure.The cross section has changed after the transmission pipeline is damaged by corrosion in service,which will make the stress state change,while the stress concentration produced will also intensify the mechanochemistry corrosion,and accelerate the reduction rate of pipeline's carrying capacity.In order to understand the stress distribution and the variation law of the corrosion pipeline under the action of the load,the stress of pipeline corrosion defect is analyzed by elastic-plastic analysis method.Firstly,according to Paraphrase 4-10 of ASME B31.3,it is considered that the longitudinal stress of the pipeline is caused by the pressure,the axial external force and the bending moment of the pipe in this paper,combining with the theoretical knowledge of mechanochemistry effects,the equation between longitudinal stress and corrosion rate is obtained,so as to the equation between the longitudinal stress of the pipeline and the remaining life.Secondly,according to the equation,it is necessary to study the relationship between the internal pressure,the bending moment and the corrosion depth of the corrosion pipeline.The finite element analysis software is used to build model to analyze the corrosion pipeline,to study the stress distribution at the corrosion defects of the corrosion pipes subjected to the internal pressure and the bending moment,and studying the influence of the corrosion parameters.Finally,the stress distribution of the corrosion pipeline under the multi-load is studied.Based on this,the formula of the load resistance coefficient method is modified,which provides guidance for the strength analysis and design of the submarine pipeline.