A galvanic anode wired or welded to a structure so that it corrodes in its place and supplies protective current with no outside power. Magnesium drives the most voltage and suits high-resistivity soil, zinc suits low-resistivity soil and seawater, and aluminum-zinc-indium alloys dominate offshore. Buried anodes come prepackaged in cloth bags of gypsum, bentonite and sodium sulfate backfill. Output is limited, so they suit coated, isolated or small structures.
Service line only needs a couple of 17 pound sacrificial anodes, no point running a rectifier for that.
Water prepackaged anodes in after backfill. A dry bag can take weeks to start delivering full current.
Also heard as
- galvanic anode
- packaged anode
Related terms
Mag anode
Field name for a magnesium sacrificial anode, the high-voltage choice for high-resistivity soils.
Zincs
Boat and marine slang for the sacrificial anodes bolted to hulls, shafts, outdrives and heat exchangers.
Galvanic corrosion
Accelerated corrosion of the more active metal when two dissimilar metals touch in a shared electrolyte.
Cathodic protection
Shielding buried or submerged steel from corrosion with DC current from sacrificial anodes or a rectifier.
ICCP
Impressed current cathodic protection: CP powered by a rectifier pushing current through long-life anodes.