Boundary Element Method Simulation Of Cathodic Protection System

As the increasing demand of the energy, the oil and gas exploitation of deep sea has attracted great interest of the people. This means that it will require higher standard of the design and protection of the marine structures. In the traditional cathodic protection(CP), usually an excessive safety parameter is decided to ensure the safe condition. However this sometimes will induce the waste of the metal materials and overprotection in some area.In this paper, a boundary element method (BEM) is brought forward to simulate the real condition of the marine structure under cathodic protection. The boundary integration equation is concluded, and the constant element is used to discretize the boundary. The polarization of the anode and the cathode is treated as the boundary conditions. Two methods are used to fit the polarization curve, which are Newton-Raphson iteration method and piecewise linear approximation method. A boundary element method simulation program CPBEM for cathodic protection is developed with FORTRAN. Two examples are used to verify the validity of the program, and the results indict that the program is effective.The corrosion behavior of the pipeline steels in sea mud is discussed. Weight loss method and polarization method are taken to investigate corrosion characters of the two kinds of steels, SML and ERW. Through the Gray Relational Analysis, the correlation of the environmental parameters of the sea mud and the corrosion rate of the steel in sea mud is explored.