Failure Pressure Analysis Of High Strength Submarine Pipeline With Corrosion Defects

Submarine pipeline is the most direct and effective transportation method for offshore oil and gas transportation,which plays an important role in offshore oil and gas development and transportation.The operation environment of submarine pipeline is complicated,and if the pipeline damage leads to oil and gas leakage accidents,it will cause economic losses and ecological environment pollution.Corrosion is the main cause of pipeline damage,and the reduction of effective wall thickness reduces the carrying capacity of pipeline.In order to predict the failure pressure of submarine pipeline with corrosion defects and ensure the safe operation of pipeline,this paper studies the failure process of submarine pipeline with corrosion defects,and the research contents and innovative results are as follows:(1)Based on the literature,the pipeline test data are counted and analyzed.It is better to use stress criterion to judge failure of pipeline by establishing pipeline model.By comparing the experimental and finite element results,the feasibility and accuracy of the proposed method are verified,and the average error is only 2.53%.(2)The influence of length,width and depth of single defect on failure pressure of X80 pipeline with uniform wall thickness was analyzed.The accuracy of different failure pressure calculation formulas was compared.According to the comparative analysis results,the calculation formula suitable for X80 pipeline was obtained.The average error and standard deviation of the results were about 2.1% and 1.9%respectively.(3)The influence of uniform wall thickness double defects on failure pressure of pipeline was studied.The change of circumferential spacing has no effect on failure pressure.The applicability of the double defect influence criteria in different methods was compared.Combined with the correlation analysis,the average error of the double defect failure pressure evaluation method established on the basis of the failure pressure calculation formula of X80 single-defect pipeline was about 2.8%,indicating high accuracy.(4)The influence of step defect on failure pressure of pipeline is studied.The depth ratio and length ratio of upper and lower defect increase,and the failure pressure decreases.When the width ratio increases,the failure pressure increases.The change of the relative position of the upper and lower defect does not affect the failure pressure.Comparing the accuracy of different methods in calculating the failure pressure of X80 pipeline with step defect,it is considered that the single-defect failure pressure calculation formula can be used to evaluate the pipeline with this type of defect.