Cathodic protection

• Description :

The networks are protected against corrosion by the continuity of the PE coating on the parts. However, for networks located in areas with increased corrosion risks (presence of high stray currents), it is recommended to also install cathodic protection.

Two types of protection can be supplied and installed, the choice being based on the installation to be protected:

• Cathodic protection by sacrificial anode. *
  The principle is to create a cell by coupling with a less noble metal, which corrodes, resulting in directed corrosion. The metal to be protected (steel of the TUCAL sheath) acting as the cathode is connected to a more electronegative protective metal acting as the anode. The potential of the metal to be protected becomes more electronegative than its natural corrosion potential. Consequently, the oxidation reaction does not occur at the cathode but at the anode, hence the term "sacrificial" anode.

Anodes are generally distributed at regular intervals along the duct to be protected, except in the case of non-uniform corrosion or geometrical and technical constraints.

• Protection by imposed current. The principle consists in imposing a current between the metal to be protected, the cathode, and an auxiliary electrode, the anode. An external current source is required. The positive terminal of the current source is connected to the auxiliary electrode and the negative terminal to the sheath to be protected. Above a certain current, the steel no longer corrodes.

In both cases, the ends of the network are delivered equipped with insulated flanges in order to insulate the network electrically, so that the cathodic protection operates correctly. All other necessary components are supplied and installed under the supervision of INPAL Energie.