Study Of Residual Strength For The Buried Steel Pipeline Based On Finite Element Methord

In recent years,with the rapid construction of infrastructure in China,the application of buried pipelines is increasing,especially steel pipelines are the most widely used.As the pipeline increases with the age,different defects will occur in individual parts.It will cause pipe accidents such as pipe bursts and leaks,and the consequences of pipeline accidents are generally more serious.Through the study of the residual strength of the buried pipeline,we can better judge the service situation of the pipeline and provide a scientific theoretical basis for the maintenance,replacement or depressurization of the pipeline.The work and achievements of this paper mainly include:(1)By comparing the failure pressure calculated by the evaluation criteria and finding the failure pressure obtained by the pipeline blasting test in the literature,it can be concluded that the obtained ASME B31 G criterion is applicable to the residual strength evaluation of low-strength pipelines;the DNV-RP-F101 standard is applicable to the residual strength evaluation of medium-high strength pipelines.(2)Through the finite element software ABAQUS to simulate the influence of axial length,width,depth of single defect on residual strength.For a single defect,it can be found that when the defect length(?),the failure pressure of the pipe varies little with the length of the defect;the residual strength of the pipeline decreases linearly and rapidly with the increase of the depth of the defect;the effect of the defect width on the residual strength of the defective pipeline is small and negligible;In short,the depth of the defect has the greatest impact on the residual strength of the pipe.(3)For adjacent defects,when the ratio of defect depth to thickness d/t is less than 0.4,the ultimate distance of interaction between adjacent defects(?);When d/t is more than 0.6,the ultimate distance of interaction(?);the angle between adjacent circumferential defects has little effect on the residual strength of the defective pipe and can be ignored.(4)By comparing the failure pressure of the pipeline with the finite element simulation and the failure pressure calculated by various evaluation criteria,it is found that the finite element simulation results are closer to the pipeline blasting failure pressure,which indicates that ABAQUS simulation of residual strength of steel pipeline is feasible.(5)Based on MATLAB GUI and the theoretical research results,the residual strength evaluation software for buried steel pipelines is developed for pipeline steel grades and defect types.It can be used to evaluate the residual strength of low,medium and high strength steel grade pipelines with single and complex defects.The work efficiency is improved.(6)For pitting corrosion,uniform corrosion and local corrosion,the corresponding geometrical model is established,and the remaining life prediction system for the above three corrosion defects is formed,and verified by specific examples.