Study On Damage Degree Of Oil And Gas Pipeline With Simple Depression

As the blood of the national industrial system and important strategic resource to the country, petroleum and natural gas should get reliable safety guarantee in the process of transport and storage. Due to the serious consequence leaded by the failure of petroleum pipeline or natural gas pipeline, more and more researchers start to focus on the security of pipeline. Pipeline defect is the main reason to the failure of itself. And dent defect is one of the general defect types. Therefore, it is necessary to conduct a further study on pipeline defect, that will be meaningful to guarantee the security of pipeline operation. In accordance of plain dent in pipeline, the work done by this paper is as follow:(1) On the basis of domestic and overseas references, according to conclude and compare the present research of dent intension of pipeline, fatigue life of pipeline and principle of ductile fracture, this paper put forward research contents, technical route and the feasibility of demonstration method.(2) Introduce the classify standard of pipeline dent defect, the form reason of dent and the method to detect pipeline dent briefly.(3) Establish finite element model of pipelines through ANSYS, and simulate the process that indenter press on pipeline then form dent defect. After that, analyze the relationship between dent depth and damage degree of pipeline on conditions of different parameters which include internal pressure of pipeline, dent size and pipeline size, on the basis of Oyane principle of ductile fracture. In addition, matching calculate results which obtained from the analysis, then get expressions in range of application. Finally, remove indenter, then analyze the spring-back of dent caused by the internal pressure of pipeline and the elasticity of material.(4) Analyze the relationship between residual stress of dent area and different parameters after removing indenter Then, remove residual stress of pipeline, compare the fatigue life respectively of pipeline with residual stress and the one without residual stress based on the fatigue life model pressed by stress engineering service institution. Finally, get such a conclusion that residual stress does have influence on the fatigue life of pipeline dent.