The buried structures to which cathodic protection can be applied are pipes (gas, oil, water), buried tanks, well linings, above ground storage tank bottoms and sometimes piles or similar structures.
The corrosion of these structures has various origins:
- local aggressivity of the soils
- differential aeration due to different grain size distribution of the soils
- stray currents circulating in the grounds, due sometimes to close cathodic protections.
The pipes are covered by organic coatings, containing asphalt or polymers.
It should be noted that cathodic protection is mandatory for buried pipes transporting petroleum gas or chemical products, as well as for buried tanks with flammable gas or liquefied petroleum gas (LPG).