A Study Of Strength Changing Of Jing Xian Pipeline

Pipeline has been a very important way to transport oil and gas. With year of serviceincreasing, corrosion in pipeline will be more seriously. With the development of corrosion,pipeline will be more dangerous. Jing Xian pipeline has played an important role in oiltransportation in Changqing Oilfield. After running for more than10years, there has beendiscovered some important defects in pipeline. In view of the importance of Jing Xian pipeline,the assessment of residual strength of the Jing Xian pipeline should be taken immediately.As the basis of study, this paper introduce the history of assessment of residual strengthof pipeline first. In order to have a good result in assessment, this paper select two standards toassess the residual strength of Jing Xian pipeline. The evaluation is all based on the test data ofJing Xian pipeline. With the data, we can get the MAOP for each defect on Jing Xian pipelineand the results show that Jing Xian pipeline is safe.This paper also use the finite element method to take a further analysis of residualstrength of Jing Xian pipeline. In finite element study, this paper select linear elastic model toanalyze. After modeling each defects on Jing Xian pipeline, we increase the internal pressurestep by step. In each pressure, we calculate Von Mises pressure of pipeline model and compareit with tensile strength of the material used in pipeline. If Von Mises pressure is greater thantensile strength, we take the internal pressure as MAOP of defect. This paper also make acompare between the finite element method and the standard method. The result of compareshow that SY/T6477-2000standard is better, ASME B31G criteria has a more conservativeresult in assessing.Finally, this paper analyze the remaining life of defects on Jing Xian pipeline. First Wemodeling pipeline and by reducing the wall thickness of the pipe model gradually, we candetermine the minimum wall thickness of pipeline. And we can get corrosion rate of eachdefect by linear extrapolation. Based on the data we get above, we can finally get theremaining life of each defect.