A new strategy for cathodic protection of steel in fresh water using an aluminum electrode as an impressed current anode: a case study

Abstract

Abstract In fresh water, aluminum cannot be used as a galvanic anode for the cathodic protection (CP) system because the accumulation of oxide films causes the electrochemical potential to change to an extremely noble potential (passivation). To work correctly, aluminum anodes often require chloride ions in the electrolyte. Because impressed current anodes are fairly inert, the anode component corrodes at an extremely low rate. The present case study focused on a novel strategy for employing aluminum anode as an impressed current anode for cathodic protection inside a fresh water storage tank made of X65 steel. According to the impressed current scenario, 0.6 A of current supply and 0.33 V of voltage were required to properly protect the X65 steel tank’s internal surface area of 421 m2. Prior to the implementation of cathodic protection, the potentials varied from −0.474 to −0.509 V (vs. Ag/AgCl). After 30 days, 60 days, and 90 days of cathodic protection, the potential values inside the protection zone showed a significant change (−0.800 and −1.150 V vs. Ag/AgCl). The results demonstrate that aluminum anodes with a considerable performance (current capacity) and a minimal consumption level can really be employed as impressed current anodes in fresh water applications.