Cathodic Protection grade graphite is an especially good material for use as an anode. Graphite is an excellent conductor of electricity, is chemically resistant, and is easy to machine. Excellent long term performance histories and economics have made the solid graphite anode very popular for impressed current systems.
MESA manufactures a complete line of graphite anodes which are produced in accordance with strict quality control guidelines. The anodes are composed of high quality petroleum coke which is mixed with coal tar binders and extruded into various diameter rods. The rods are heated repeatedly at temperatures in excess of 2600 degrees C and the cooled. The end result of this manufacturing process is an anode with a high percentage of carbon, which can deliver effective protection at a relatively low consumption rate. In buried soil electrolytes, this consumption rate varies between 0.4 and 2.0 pounds/amp-year. The recommended current density for graphite anodes is 0.5 amps/square foot.
Because graphite is porous, anode life can be increased by filling the pores with an enhancer; MESA treats its graphite anodes with microcrystalline wax. This impregnation limits any electrochemical activity to the surface of the anode and reduces any tendency for the reaction to occur in the pores of the anode itself. It also acts as a barrier against moisture intrusion which could cause deterioration of the anode and possibly the anode connection.