Strain-based Design Pipeline Strain Capability Study

Pipeline is considered as the most reasonable and economical way to transport oil and natural gas. With the developing of hydrocarbon energy exploitation in harsh entironment such as seismic area, discontinuous permafrost and offshore, the strain-based design are present to meet the plastic deformation of pipelines. The methodology require line pipes with more strain capacity.The dissertation study mainly about the strain capability of line pipes for two steps. Firstly the material properties related to strain capacity are tested, secondly, the critical compressive strain are researched by full-scale test and numerical simulation.Small coupon test results are insufficient to provide convincing the deformation behavior prediction because pipelines are always service under combined load conditions such as bending moment and internal pressure, therefore full-scale bending test is the direct measurement of pipeline strain capacity. Besides this, reverse engineering technology and finite element analysis are also involved in this study.The study investigated the factors influencing strain capability of pipeline. The factors include Y/T ratio, uniform elongation, stress ration, stress-strain curve shape, initial geometric imperfections of pipe body, etc. To sum up, this study has reference value to evaluating strain capability of line pipes for strain-based design.