Examples of this type of anode include scrap iron or steel and cast iron. The anode is deliberately dissolved to provide the electrons required to polarize the structure. Consumable anodes can be used in buried or under immersed conditions. They have consumption rates of approximately 9 kg A-1 y-1. and maximum current densities are in the order of 5 A m-2. Due mainly to their high consumption rate the use of such anodes is rather rare unless a redundant source of iron or steel is readily available such as an old ship beached below low tide, a disused pipeline, well string etc. However, since such structures are frequently massive, they represent a very low resistance to earth and therefore can make the cathodic protection engineer's life much simpler.