Stray current corrosion has become one of the important reasons for corrosion failure of buried steel pipelines. In this paper, based on Comsol Multiphysics software, the influence of stray current on the corrosion of buried steel pipes under cathodic protection was simulated and analyzed, and the influence of leakage voltage, soil conductivity, pipeline buried depth and other factors on the cathodic protection potential was analyzed. The simulation results show that under the action of -1V cathodic protection, when the leakage voltage exceeds 10V, the interference degree of stray current is very strong, and the cathodic protection is likely to fail. Under cathodic protection, soil average current density was positively correlated with soil conductivity under a certain leakage voltage. With the increase of burial depth, the positive shift of pipeground potential decreases and gradually returns to the cathodic protection potential level. Therefore, the buried range greater than 1.5m is determined within the allowable range of field technology and economy, and the combination of cathodic protection can better prevent stray current corrosion interference. The research in this paper has important guiding significance for further understanding of stray current corrosion mechanism of buried steel pipelines.
Stray current corrosion has become one of the important failure factors of buried steel pipelines. In this paper, the propagation law of stray current in soil was simulated and analyzed based on Comsol Multiphysics software, and the relationship between the decay law of stray current potential and soil resistivity was obtained. The effect of the damaged area of the anticorrosive layer, soil oxygen concentration, soil pore saturation and other factors on the pipeline ground potential at the inflow and outflow point of stray current is simulated and analyzed. The damaged area of the anticorrosive layer has a more obvious effect, the current density at the defect edge is higher than that at the center, and the outflow stray current density at the damaged point of the anticorrosive layer increases with the decrease of the damaged area of the anticorrosive layer, and the corrosion becomes more intense. Oxygen is mainly consumed at the inflow of stray current, and oxygen reduction reaction occurs. With the increase of soil porosity, the diffusion coefficient of oxygen decreases, while the conductivity of soil electrolyte increases. As the influence of soil electrolyte conductivity is larger than that of oxygen diffusion coefficient, the corrosion becomes more intense with the increase of soil porosity. The research in this paper has important guiding significance for further understanding of stray current corrosion mechanism of buried steel pipelines.
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