Pipeline To Change Gas Pipeline Assessment Of Residual Strength

With the rapid development of national natural-gas industry, rebuilding gas-pipeline with oil-pipeline which is rejected or stops transportation due to lower economic benefit possesses the advantages of smaller invest, lower risk, simpler primary stage work, and shorter rebuilding cycle. In allusion to the engineering practice of oil-pipe altering to gas-pipe, this paper makes exploratory research to three aspects about it. They are full-scale estimation of corrosion degree, prediction and evaluation of residual strength of corroded pipelines. This paper systematically puts forward the theory and method residual corrosion strength assessment of oil-pipe altering to gas-pipe.Starting with corrosion mechanisms, the corrosion characteristic and generating condition of usual corrosion type of piping are quite entirely analyzed. In allusion to the objective actuality including much corrosion factors and complicated relation, this paper applies grey correlation analysis and analytic hierarchy process to determine weight of every corrosion factors. The corrosion status of pipeline is synthetically evaluated by fuzzy mathematics method, and the corresponding computation procedure is programmed. The mathematical model of corrosion status of post-rebuilding pipeline is established by grey theory and fuzzy mathematics. Using this model, the corrosion status of post-rebuilding pipeline is predicted and analyzed. At the same time, this paper respectively introduces the calculational methods of the length, depth, and corrosion area of corrosion deficiency, and emphatically introduces the three steps evaluation. In the end, adopting elastoplasticity triaxiality finite element analysis and with aid of ANSYS software, this paper evaluates the residual strength of horizontal straight-tube with corrosion deficiency and gets the comparatively ideal consequence.