Study On Cathodic Protection Parameters Influence Of Buried Pipelines With Coating Defects

The cathodic protection parameters of buried pipeline can be used to analyze the status of the pipeline's anticorrosive coating and the effect of its cathodic protection, which has important implications for the early detection of corrosion. This paper mainly researched the variation laws of the cathodic protection parameters under case of pipeline's coating damaged.In order to analysis the variation laws of the cathodic protection parameters influenced by the coating's defects, soil characteristics etc., through large number of experiments, this paper studied the influence of factors — buried depth, the damage's area, numbers and location, the soil resistivity and applied voltage—on the cathodic protection parameters such as natural pipe-to-soil potential, cathodic protection potential, IR drop and so on.IR drops has a significant impact on the cathodic protection parameters and resulting to the error that could not eliminate. To improve the accuracy of the experimental data, this paper upgraded the polarize probe with the principle of making test block's material consistent with the pipeline's and the bare area of the test block close to the damaged area of pipeline's coating, and then it also verified the effectiveness of the device. The measurement result showed the date of the polarize probe is reliable. Making use of the improved experiment device, this paper studied the relationship between the IR drops and the influence factors such as the buried depth, coating's defects, etc. By the orthogonal experiment, the paper gets the mathematical model presenting the relationship between the IR drops and factor under with this paper's limit contitions. And it also gets that the damage's area,location and applied voltage of the pipeline have obvious influence on the IR drops.By reaching the effect laws of cathodic protection parameters and the IR drops with the pipeline's coating damaged, this paper provided new thinking and analysis basis for the cathodic protection staff to evaluate the cathodic protection's effect and the coating's status of pipeline.