Sacrificial anodes have been a common usage in a multitude of applications for many years. They protect all ships at sea, underground and above ground pipelines, boilers, hot water storage tanks and generally steel structures immersed in water or damp soil conditions where corrosion could be a problem.
The corrosion (rust) is the result of electrolytic action traveling through moisture or fluid to home in on the metal surface at risk. Depending upon the existing conditions such as amount and quality of the fluid (water?) and the effective presence of any other protective coating on the metal surface, the rate of anode corrosion can vary substantially.
For fresh and groundwater applications our anodes are of a particular grade of magnesium, which is "electro-negative relative to steel". The anode will become part of the circuit and essentially waste away instead of the metal you want protected. This type of galvanic protection is called sacrificial and the principle of electrolytic corrosion control is called cathodic protection.
Many of the large domestic water storage tanks today have cement coatings thus eliminating the problem of internal rust. Some areas of the tank cannot be protected by the lining due to the necessity of water flow i.e. couplings, inlets, outlets, etc. Therefore many tank manufacturers initially supply anode protection provided by the insertion of special tank anodes c/w end mounting brackets suitable for either bolting or welding directly to the inside walls below the water level. These anodes should be replaced on regular schedule as directed by your anode specialist. Similar anodes can be very effective in protecting metal pipelines, bore heads, casings, etc.