Sacrificial Anodes are most commonly used to protect metallic structures in electrolytes because of their simplicity of installation and maintenance free operation. Of the alloys available for sacrificial anodes, alloys of aluminium have proven to be the most economical in seawater or very low resistivity muds.
Knowing the total submerged and buried steel areas, the water resistivity and the required system life, a Corrosion Engineer can determine precisely what energy will be required to protect a structure and can design a galvanic system to suit the environment requirements.
Freely corroding mild steel in seawater has a resultant potential between anode and cathode of approximately –0.50 to –0.60 volts compared to a silver/silver chloride reference electrode. When cathodic protection is applied, it will be noted that the surface potential of steel will change to more negative than –0.80 volts when measured relative to a silver/silver chloride reference cell. Thus by using this simple practical measurement, it is possible to determine whether corrosion has been completely eliminated or not.