Research On Stray Current Effect Of Cathodic Protection Potential Of Buried Steel Gas Pipeline

The current leakage from running trail to trail ballast or the surrounding soil medium is called stray current when metro runs.While many steel gas pipeline buried surround metro,stray current can severely corrode steel gas pipeline,influence people’s life and property safety.On the basis of consulting the domestic and foreign literature,introduce The cathodic protection technology of buried steel gas pipeline,characteristics and corrosion mechanism of stray current, measurement techniques and evaluation of cathodic protection potential and stray current.Then respectively use numerical calculation and finite element simulation calculate the distribution of cathodic protection potential,running track potential,running track current,corrosion current and the stray current.The main contents are as follows:1、In the case of Guangfo metro stray current,The potential value of the parallel steel gas pipeline is measured by the close interval potential measurement method,study on the effect of stray current on the cathodic protection potential of pipelines.Establish a stray current on cathodic protection potential evaluation index.2、Using the mesh current method, analytical method and finite element method to calculate the buried steel gas pipeline cathodic protection potential distribution,comparing the calculated results with the measured values of the actual engineering three.The results show that:the finite element calculation results approach to measured values of the actual engineering and the error is less than 5%,verify the accuracy of the finite element method.Then using the finite element method to research cathodic protection potential distribution of steel gas pipeline under different parameters.3、Establish the mathematical model of running track to soil,deduce the distribution formula of running track potential,running track current,corrosion current and stray current,using MATLAB to study the distribution rule of stray current under different parameters.The results show that:stray current and corrosion current value is very small when track-soil transition resistance is greater than 70? ?km;The leakage of the stray current and the corrosion current is smaller under the condition of steel structure network.4、Establish the finite element model of running track to soil to steel gas pipeline,using finite element software to calculate the cathodic protection potential distribution of pipeline under metro stray current,and the distribution of cathodic protection potential under different parameters.