The Study On Evaluation Methods Of Continuous Pitting Corrosion In Long Pipeline

Pipeline oil or gas pipelines, whether it is buried in the ground, buried in the deep sea, set up in the air or tiled on the ground, are subject to the internal and external pressures, its own gravity, the internal fluid or gas gravity, as well as from the soil, water, air, and other corrosion. All these affect the integrity of the pipeline, the occurrence of a wide range of corrosion and defects. Once the corrosion is found in long pipeline, the corrosion will could impact of the safe operation of pipelines. In order to safeguard state property and environmental safety, the need for the corrosion of the pipe is known to evaluate the area. Advantages and disadvantages of each method of comprehensive evaluation, this paper calculated as part of API579 standards, calculating the residual strength of long-distance pipeline. The use of finite element analysis as part of the simulation, in addition to the actual measured pressure in the pipeline for the stress and displacement deformation experiment, comprehensive evaluation of the results are obtained to ensure that the results accurate and scientific.In addition, calculated taking into account the large amount of API579 standards, and the shortcomings of calculations to calculate the corrosion defect, the C language is used to program the evaluation methods of API579 standards, a relatively simple and convenience calculation is obtained, so that a large number of engineering applications can.Theory of computing, software simulation, experimental analysis and software programming the four parts constitute of a complete system which evaluate long-distance pipeline continuous pitting corrosion. To API579 criteria based on theoretical calculations, to judge by the type of corrosion, and selecting the appropriate methods of evaluation, establishing step by step evaluation system, calculating the residual strength of long-distance pipeline. And then through the example of the finite element simulation of long distance pipeline corrosion defects by building models, meshing, loading, and post-processing and other operations, the simulation of the corrosion defects with long-distance pipeline stress and deformation displacement and so on. Then, putting the experimental results with theoretical results and simulation results, getting the results are API579 criteria suits for evaluation of pipeline corrosion, and the results of the evaluation are right; experiments also verify the accuracy of the finite element simulation results. Finally, compiling a complete set of software which is the method of calculation, this method of evaluation has improved than before, eliminating the need for a large number of repetitive calculations, saving time and effort.