Non-linear Finite Element Analysis For The Corrosion Defects Of Pressure Pipelines

Pressure pipeline is widely used in industrial production and people’s life. Pipelines safety is always vital. Although pipelines are of importance in the petroleum industry failures due to corrosion defects have become a significant, recurring and an expensive operational, safety and environmental concern. With the passage of time the corrosion that occurs either at a localized point or onto a large area cause the metal loss hence the strength or in other words load bearing capacity of the pipeline is reduced. The distribution of actual pipeline corrosion defects tend to be random. Therefore, in order to ensure the safety of pipeline operation, it is necessary to evaluate the residual strength of corroded pipeline, examine the influence of various parameters on failure stress of the pipelines with adjacent corrosion defects, and analyze the interaction effect of adjacent corrosion defects on the burst pressure of pipelines, and to provide reference for safety evaluation of pressure pipelines.In this thesis, by comparing the actual corrosion pipe blasting experiment results and the literature results, verify the adjacent pipeline corrosion defects on the accuracy of the finite element model. To adjacent corrosion defects on the corrosion of pipeline to carry out the nonlinear finite element analysis, to study the corrosion defect spacing, corrosion defect depth and length of the corrosion defects of interaction and the influence of pipeline failure pressure, at the same time identify a set of feasible criterion of interaction, and verify the new limit range are put forward. Studies show that the axial adjacent corrosion defect corrosion defect length and depth of the corrosion defects are the important factors influencing the axial distance limit; There is also a maximum impacting distance between circumferential adjacent corrosion defects just as the central angle which represents the fraction of the circumference is 20o,the corrosion depth has little impact on the maximum impacting distance of the circumferential adjacent corrosion defects.For complex corrosion defects, the depth ratio and the length ratio of the deep and shallow defect are the two main factors influencing the pipeline failure pressure, and the width of the deep and shallow defect has little impact on the pipeline failure pressure.