Sample Specifications for High Potential Magnesium Anodes
The magnesium alloy utilized shall be a high-potential alloy derived from primary magnesium. The AZ-63 or H-1 alloy is not acceptable. Acceptable trade names include MAXMAG or GALVOMAG. Anode chemical composition must conform to ASTM B843 as follows:
|.50 to 1.3% maximum|
Magnesium alloy shall meet minimum requirements for open circuit potential and current efficiency. Testing of these properties shall be in accordance with ASTM G97 Standard Test Method for Laboratory Evaluation of Magnesium Sacrificial Anode Test Specimens for Underground Applications. Upon request, supplier shall submit Certificate of Conformance.
All anodes shall have a minimum open circuit potential of -1.70 volts referenced to Cu/CuSO4. Minimum acceptable current efficiency is 45%.
Anodes shall be cast with a steel core. One end of the anode shall be recessed so that the core is accessible for lead wire connection. The anode lead wires shall be ten (10) feet in length and shall consist of AWG No. 12 solid copper wire with Type TW insulation. The lead wire shall be connected to the core with silver solder. The entire connection area shall protected by filling the anode recess with an electrical potting compound.
Anodes shall be packaged in a permeable cloth bag containing a backfill mixture of the following composition:
|Powered Wyoming Bentonite|
|Anhydrous Sodium Sulphate|
Backfill shall have a grain size so that l00% is capable of passing through a 20 mesh screen, and 50% will be retained by a 100 mesh screen. The mixture shall be firmly packaged around the anode within the cloth bag. Anodes shall be protected from shipping and handling damage by suitable shipping bags or boxes.