Analysis of Pipe Size Influence on Pipeline Displacement with Plain Dent Based on FE Calculation

According to the report of the United States transportation department, mechanical damage is one of the most important reasons for the pipeline accident .The most typical form of mechanical damage is indentation. Dent defect is one of the important factors affecting pipeline fatigue life, and it will greatly reduce the fatigue life of the pipeline in service. Meanwhile the dent displacement will be changed with the operation pressure fluctuations of the in-service pipeline, resulting in a circular bending stress, which directly affect the pipeline fatigue life. For typical plain dent on pipeline, the finite element models were established under different circumstances. A large number of the calculation results were sorted and inducted. On this basis, the results were analyzed by univariate. Non-linear regression analysis was utilized to fit the results, some specific expressions of the relationship between the dented pipeline displacements and the diameter and wall thickness of pipeline are obtained after much calculation and analog.