Anode Life and Efficiency

Life of a magnesium anode is directly proportional to its current efficiency. Magnesium anode alloys have a nominal efficiency of 50%. However, significant variation from this efficiency will directly impact anode life. It is not uncommon for anodes meeting all chemistry requirements to still exhibit efficiencies much lower than the nominal 50%. Anode efficiency should be a critical part of the anode specification. Minimum efficiency should not fall below 45%.

In his book “Control of Pipeline Corrosion”, Peabody provides a formula for calculation of anode life.

L = life in years
         Wt = weight in pounds
                 I = current in amperes

D. A. Tefankjian in his article, “Application and Maintenance of Control Facilities” offers the following formula for calculating anode life.

L = life in years
       Wt = weight in pounds
                       I = current in milliamperes