Use of Sacrificial Anodes as Protection of Galvanized Steel Exposed to Potassium Chloride and Urea Fertigation Solutions

Abstract

Corrosion is one of the major causes of metallic pipes deterioration used in irrigation, such as galvanized steel. Its magnitude is directly linked to the quality of the water flowed by these pipes. Thus, the use of cathodic protection combined with pipe coating is used to achieve a greater protection. This study aimed to evaluate the effectiveness of using cathodic protection by the sacrificial anode method to reduce the mass loss, related to corrosion, in specimens of galvanized steel caused by fertigation solutions containing urea or potassium chloride, at 10 g L⁻¹, using Zn, Al and Mg anodes, in addition to a control treatment, without protection. For this, immersion tests were conducted to obtain the mass loss per area, by simulating 10 years of operation. The results showed that with the use of sacrificial anodes it is possible to reduce the mass loss in galvanized steel caused by potassium chloride solutions for fertigation; however, this type of cathodic protection may not be effective in protecting urea-containing solutions from overall corrosion. The aluminum anode is the most suitable to use in solutions with high electrical conductivity, as it can reduce the mass loss caused by potassium chloride by up to 78% compared to the unprotected treatment.