We are reviewing methods of reducing corrosion in ferrous metallic structures that are above ground, direct-buried, and submerged such as our fuel tanks and the piping associated with it. What methods are out there to reduce corrosion? This is one of the factors that is compromising the structural integrity of these items.

I would recommend using a type of Cathodic Protection. This is a method to reduce corrosion by minimizing the difference in potential between anode and cathode by applying a current to the structure to be protected from some outside source. When enough current is applied, the whole structure will be at one potential. There are two main types of cathodic protection systems: galvanic and impressed current. In both systems current flows from an external metallic connection (wire) and anode into the electrolyte.

Galvanic System – a galvanic cathodic protection system makes use of the corrosive potentials for different metals. In a galvanic system, an inert object that has a much more negative potential such as a magnesium or zinc anode is placed adjacent to the structure to be protected and an insulated wire (metallic connection) is installed between the object and the structure. The inert object will become the anode and corrode sacrificially to protect the entire structure (becoming the cathode). The galvanic cathodic protection system is called a sacrificial anode cathodic protection system because the anode corrodes sacrificially to protect the structure.

Impressed Current System – a current from an external power source to an anode is used to protect the structure. The anode and the structure are connected by an insulated wire and current flows from the anode through the electrolyte onto the structure. The external power source is usually a rectifier that changes input AC power to the proper DC power level. The anodes in these systems are typically high-silicon cast iron or graphite.

We use both methods of cathodic protection so let me know if you need any additional information.