Numerical Simulation Of Cathodic Protection Potential Distribution Along Long Distance Pipeline

The physical model of pipeline cathodic protection potent ial distribution is established in this paper, and the corresponding mathematical model is deduced. The mathematic model is discretized by the boundary element algorithm, and solved by programming calculation. Because long distance pipelines go through different areas, the environment is complicated, so the BEASY software is used to established the model and researched the influence of changes of the soil resistivity along the pipeline with axial, radial and pipeline buried depth direction on cathodic protection potential distribution. For long distance pipelines, there are paralleled pipelines, branches, and cornering. The BEASY software is used to establish the model and research the influencing rule of paralleled pipelines, branches and cornering on the cathodic protection potential distribution. Finally, on the basis of the actual research on the long transmission line, the BEASY software is used to establish the model and simulate the potential distribution along the pipeline with full consideration of t he different resistivity along the pipeline, and compared with the measured values, the boundary element method was verified effectively in the study of complex terrain pipeline cathodic protection.The physical model established in this paper is similar to the actual situation, and pipeline unit model using the boundary element method can discretize governing equation well. Compared interior design experiments with the results of the programming calculation, the programming calculation is correct, and presents a recommended value of the number of discrete pipe unit.Through researching the influence of the soil resistivity on cathodic protection potential distribution, cathodic protection potential shifts positively with the increase of soil resistivity; with high soil resistivity area decreased, potential distribution along pipeline shifts positively, and protection level decreases with the degree of polarization weakened; When the soil resistivity near anode increases, cathodic protection potential along the pipeline shifts positively, the effect of cathodic protection is weakened; cathodic protection potential of anode located in the low resistivity soil is lower than the situation of the anode located in high soil resistivity.Through researching the influence of pipe parameters on cathodic protection potential distribution, with the increasing of the horizontal distance between two pipelines, pipeline corrosion potential shifts negatively as a whole, and potential distribution of the whole pipeline becomes uniform; when the pipeline has a branch, cathodic protection potential distribution shifts positively as a whole, cathodic protection effect is weakened. In the branch of the pipeline, cathodic potential shifts positively; the change of direction in pipe lines or the moved anode, cornering angle and position will have an impact on cathodic protection potential distribution to some extent.Through numerical simulation of cathodic protection potential distribution in a real pipeline, the boundary element method can use to study pipeline cathodic protection potential distribution in complex regions; the simulation results are very similar to the measured values.