The Establishment And Applied Research Of Mathematical Modeling In Cathodic Protection Of Submarine Pipeline

The anode is scanned with cyclic voltammetry method in natural seawater, four times and sixteen times diluted seawater which will be used in the simulated experiment. It is confirmed by the experiment the currents generated by the aluminum anode can meet the critical values which are required in the simulated experiment. The anode can reach the activation performance requirement of the simulated experiment in a few hours. The samples of steel wire with and without calcareous deposit are scanned with cathodic polarization method in three kinds of seawater, and the value range of polarization resistance is got which will be used in the numerical calculation.Based on similarity and dimensional analysis, four meters of steel wire is used to simulate actual submarine pipeline in the simulated experiment. The polarization performance of the sacrificial anode and the steel wire protected is studied with the experiment and the boundary condition for numerical calculation in cathodic protection is obtained. The parameters can be used to prove whether the mathematical modeling established is correct. The simulated experiment provides base information for cathodic protection design of actual submarine pipeline and it combines numerical calculation and cathodic protection design.Because of space differences of the points on the steel wire, there are also differences between the polarization resistances of the points. The steel wire is divided into ten sections on average and every section is connected to the anode in the natural seawater. The conclusion is got there is a function between average polarization resistance and time, and the polarization resistances are undee with space. The mathematical modeling is established on the base of simulated experiment. With the comparison of the results of Finite Element Method, the conclusion is got that the polarization resistance in the mathematical modeling should use the value of average polarization resistance. Then numerical calculation is done with the boundary conditions which are got in simulated experiment. Because the potential of anode is difficult to measure exactly, there is distinction between the numerical result and experimental result. The potential of the point which has a distance of 0.382?L (L is the length of steel wire) to the anode can be used to be the average potential of the whole steel wire. So the numerical result is translated in order to coincide with the experimental result at the point of 0.382?L and the conclusion is got that the numerical result can be well coincided with the experimental result. It is confirmed that the mathematical modeling is reasonable and the boundary conditions are correct.Because the steel wire is effective to simulate actual submarine pipeline and the numerical result can be well coincided with the experimental result, so the conclusion is got that the mathematical modeling can be used in the cathodic protection of actual submarine pipeline through Finite Element Method. According to the parameters of actual submarine pipeline of JZ20-2, the cathodic protection design is got through numerical calculation.