محمد واقفی

Given the importace of energy in the world today, especially fossil fuels (oil and gas) and intense competition use of these resources, extensive studies on how to extract and transport oil and gas through offshore pipes in progress. Topics of oil and gas transmission by offshore pipelines have certain complexities. That’s why predicting the behavior of offshore pipeline under high pressure and temperature, is high regarded. High pressure and temperature, causing the longitudinal stress in the pipeline that is causes expansion and increase the length of the tube. Pipe and seabed interaction, prevent pipe from longitudinal expansion. As a result, the pressure loads generated in the pipeline which are caused buckling of pipe line. Buckling can cause failure in the pipeline if not controlling. In this thesis introduced a variety of offshore pipelines, causes pipeline buckling, lateral and upheaval buckling and ways to prevent unwanted buckling in length of pipeline. Given that the imperfection has a considerable impact on buckling of pipeline under high pressure and temperature, the influence of number of imperfections and instances between them and also influence of imperfections’ height on the buckling of offshore pipe is discussed. In this analysis used from Hobbs and Wang studies parameters. ABAQUSE Microsoft used for pipeline modeling and analysis. The results of this research can be summarized as stating that by increasing the number of pipeline imperfection, buckling occurs at at a higher temperature and buckling height will be less. Also, the instance between imperfection influences on the buckling temperature so that by increasing the instances between pipeline imperfections’ buckling temperature will be less.