Study On The Evaluation Methods Of Residual Strength Of Submarine Pipelines In Service

As a pipeline ages, it can be affected by a range of corrosion mechanisms, which may lead to a reduction in its wall thickness and maximum admissible internal pressure and the increase of the possibility of eventual failure. To ensure the safety of operation, it is necessary to investigate the residual strength and burst pressure of the corroded pipeline due to the inspection report and to make guide of repairmen or replacement.A number of methods of evaluation on pipelines have been already existed, such as criteria assessment, finite element analysis, reliability analysis, etc. The theoretical basic of each one is different and the scope and accuracy of the results are various.This paper deals with the evaluation of the residual strength and load carrying capacity of corroded pipelines by two reliable criteria, the ASME B31 G code and the DNV-RP-F101 code. Comparison and analysis on theoretical basis, range of application and accuracy of the results are made of these two codes respectively and calculation is done on a project case.Besides, the paper focuses on the method of finite element analysis. Based on the theory of elastic-plastic mechanics and the use of ABAQUS FEA software, the analysis of corroded pipelines is performed. In this part, some key issues on modeling and loading are discussed to optimize the model structure. 3-Demension models of a project case are made and results are performed.In the end, the paper compares the results performed by each method and discusses the diversity of complexity and range of application and provides suggestions on the priority of selection.