Corrosion prevention of storage tank bottom using impressed current cathodic protection - Experimental and simulation study

Underside failure of storage tank bottoms is a serious industrial problem which is induced by various corrosion phenomena such as under deposit, microbial and stray current corrosion and can lead to leakage of hazardous materials and explosion. Impressed current cathodic protection (ICCP) is a widely used technique to hinder these types of corrosion. However, undue design of the ICCP system can accelerate the corrosion. Therefore, it is necessary to make sure that the tank bottom is totally and properly under protection before implementation. For this aim, a FEM model is designed in this study for validating this presumption. The model is based on the potential and current density distribution of the tank bottom and is designed using the data of a real storage tank being protected in practice. Simulation results showed that the tank bottom's potential with the ICCP applied (considering voltage drop) and its polarized potential at the very first instant of current interruption both are at least -0.850 V vs Cu/CuSO4. Furthermore, based on the calculations, 0.260 to 0.280 V polarization is experienced by the tank bottom. These results confirm full protection of the tank bottom. Effects of anode arrangement, coating application and soil resistance on the system performance are also investigated and the most optimal design is proposed based on the potential distribution. Conducting such a simulation in advance can significantly increase the life time of the structure.