Simulation of linear anode-pipe cathodic protection system: Primary and secondary current and potential distribution analysis

Nowadays, the use of a linear anode in an impressed current cathodic protection system is one of the most interesting technical solutions to guarantee the corrosion protection of short pipe in common and even in congested area. The determination of the minimum distance between linear anode and pipe, and the effective parameters to reach the protection potential, can be studied at two different levels. First, the use of a primary current distribution analysis allows finding the proper distance based on the geometry, physical environmental parameters, and maximum allowable potential difference of two sides of the pipe. The second level is to consider the polarizability of the cathode, then to apply the so-called secondary current distribution analysis. The primary current distribution shows that the linear anode-to-pipe distance is mainly affected by soil resistivity and pipe diameter. Secondary current distribution analysis emphasizes that the proper minimum distance is influenced by the polarization of the cathode, i.e., the overvoltages of the two cathodic reactions of oxygen reduction and hydrogen evolution. In both approaches, soil resistivity has a predominant effect on potential distribution on the pipe surface.