Cathodic protection (CP) is widely used for protection of metallic structures from corrosion. However, an empirical approach during design and the limited coverage of CP monitoring activities can cause non-uniform potential distribution throughout the system which results in the local area vulnerable to corrosion regardless of applied CP. The use of numerical modeling tools based on finite element or boundary element methods can provide reliable and quantitative solutions to predict the CP performance. Numerical approach also supports to analyze the effectiveness of CP system and pinpoint the weak area in the whole system if it is compared with field data. In this paper case studies showing the benefits of numerical analysis to optimize the CP systems is presented, which include a microbiologically influenced corrosion of the underground steel pipeline beneath the disbonded coating and a digital twin approach of pipeline CP network based on a forecast of performance by the combination of numerical modeling and field CP data analysis to fully maximize the benefits of CP is introduced.
Cathodic protection (CP) is a well-established technique that effectively prevents corrosion of metals by adjusting the equilibrium potential of metallic structures in an electronegative direction. As the applied current increases, it reduces the anodic dissolution rate, thus leading to a decrease in the corrosion rate. The effectiveness of CP can be confirmed by measuring the protection potential values along the structures, ensuring the uniformity of the applied current, and observing the resultant potential distribution in the field.
The evaluation of corrosion and CP benefits greatly from computer-based numerical modeling, particularly when dealing with complex structural shapes, large dimensions, or congested areas where structures are interconnected, such as underground pipes network in plants. Numerical modeling allows for the processing and analysis of vast amounts of data, enabling the optimization of CP system design and the maximization of protected areas. Mathematical descriptions encompass the calculation of both on-potentials and off-potentials of structures, as well as the distribution of CP current. These parameters can be determined by solving the relatively straightforward Laplace partial differential equation, along with appropriate linear or non-linear boundary conditions. Conventional numerical tools, such as the boundary element method (BEM) or the finite element method (FEM), can readily solve this equation. Consequently, hotspots, which denote regions of under-protection or overprotection, can be quantitatively identified. This knowledge facilitates the optimization of anode quantities, their locations, and other related factors.
