Optimization of Cathodic Protection on Offshore Structures

Marine structures are one of the most important and susceptible facilities in Iran due to corrosion. The two methods of Cathodic Protection, namely, the cathodic protection with sacrificial anodes and cathodic protection using impressed current, are widely used for corrosion protection. According to the former, sacrificial anodes are installed at several points in the structure. Position of the anodes for achieving the required protection is a problem that engineers are very much interested in, and only empirical methods have so far been used to determine these positions. Empirical rules, however, might cause either overprotection or underprotection. A major goal of this research is to develop a systematic way for analysis and automated design of Cathodic Protection systems that not only deliver almost uniformly protected structures but also minimize the costs. To this end, a Genetic Algorithm (GA) routine is used to determine the optimal position of anodes on the structure such that a uniformly protected design with minimum cost is achieved. The percentage of protection in each design has been taken as its fitness criterion. To figure out the situation of corrosion protection on the structure, the entire offshore structure with its complex system at anodes and surrounding electrolyte is modeled and analyzed by a finite element algorithm. Employing GA gradually modifies the generation of designs. The design which completely protects the structure and whose cost is minimum is introduced as the optimum design. To show the capability of the proposed method in achieving the optimum design, two examples are offshore presented.