## Design Process

Design of magnesium anode systems requires a thorough evaluation of the application with consideration of the important variables. Once these variables are measured or assumed, the process typically is divided into the following steps.

**Calculate exposed surface area** - This requires an assumption of coating quality. A high quality coating can provide protection to over 99% of the total surface area. A conservative assumption of coating efficiency is 95%.
**Calculate total current requirements** - This requires an assumption of current density. The typical range of current density for steel in common soils is 1 to 3 milliamperes per square foot of exposed surface. A conservative assumption is 2 milliamperes per square foot.
**Calculate anode current output** - Using previous discussed formulas, calculate anode output considering the effect of coating, soil resistivity, alloy selection, and anode spacing. Several anode sizes should be evaluated.
**Select anode size based on life** - Once anode current outputs have been calculated, the appropriate anode size can be selected by evaluating the projected life. Typical design lives range from 10 to 20 years.
**Calculate total anode quantity** - Divide the total current requirement in amperes by the calculated anode output in amperes. The result is the estimated total number of anodes required.
**Determine anode location and configuration** - This is primarily based on local site conditions and an even distribution of current from the anodes.