Naturally, most of metallic structures are buried or stay immersed for many years. In such environments, the installation has a normal tendency to return to its original ore or rust state due to the corrosion processes.

To prevent this “underhand” degradation and penalizing damage (rupture of pressure equipment, downtime, repairs …), some methods of corrosion protection are used:

  • The metal surface coating forms a protective insulating barrier whose efficiency is limited by any degradation due to imperfections, injuries and environmental ageing.
  • The cathodic protection ensures a permanent protection of the metal exposed to the conductive surrounding. It is used with or without the coating application.


Cathodic protection consists in obtaining an electrochemical immunity through a sufficiently electronegative potential of the structure.

Such immunity is achieved when the potential measured between the steel and an electrode placed in the immediate vicinity of the metal to be protected:

The steel potential can be reduced in two ways:

Sacrificial anode protection

Impressed current protection