Here are the five ways:-
- Paint the surface of metal.
- Oil the surface of metal or keep it covered with grease.
- Electroplating it with a less reactive metal will keep it safe.
- Galvanisation that is covering it with Zinc metal it is also called sacrificial protection.
- Making it cathode, most of the underground pipes are kept safe by connecting them to the negative terminal and very small amount of current flows from it.