THE SOLUTION AGAINST CORROSION!

The Corrosion Process

The identity of a metal is defined by its potential, which is a value measured in millivolts. This potential may vary from
a zone to another according to the surrounding medium. The zones where the corrosion process may be initiated are
known as "anodic" and are defined by the most negative potential. The corrosion of the steel reacts as the dissolution
of the iron releases its electrons; such process is known as an anodic reaction:

In order for this reaction to occur, there must be both an anodic zone and a cathodic zone coexisting. These two zones must have a direct current between them, in a conducting electrolyte, such as the surrounding soil.
The corrosion process is then defined as an electrochemical process. The patch taken by the electrons during the reaction of corrosion is known as the electrolyte.

The soil surrounding the metal structure is a key element for the corrosion process. More than the path used by the electrons and the current of corrosion, the surrounding soil also affects the formation of anodic zones and the speed of corrosion on such spots of the metallic structure. The more the electrons can travel easily in the soil, the higher the speed of corrosion will be and the more the soil will be corrosive.

• Low oxygenated soil
• Ground of low resistivity
• Presence of sulfato-reducing bacteria
• Soil saturated with water
• Organic contamination (broken up by vegetation, died sheets, refuse, ...)
• Contact with highly conducting materials (ashes, coal, salts,...)
• Dissimalar materials

The lifespan of the metal posts may be strongly influenced by phenomenon of corrosion, which is susceptible of happening with within the metal posts themselves. Indeed, the corrosive spots may weaken the metal posts and also decrease their lifespan.

Furthermore, the corrosion of the metal posts is directly related to the soil's aggressiveness which mainly results from the soil's resistivity. Indeed, the less resistive is the soil, the more the phenomenon of corrosion will become important.

The metal posts that are 1,83 m (6') to 30 m (100') or more in length will be subjected to a variety of soil layers of which the resistivity will usually decrease according to the depth.

The area of the metal posts that are more susceptible to the corrosion will first be located at the line between the various layers of soil. These are the spots where a strong corrosion process occurs. The next placements where corrosion will occur will be those areas where the soil is less resistive. The areas where the phenomenon of corrosion occurs are known as the anodic areas. The areas not affected by corrosion are known as cathodic areas.

The most efficient way to minimise the phenomenon of corrosion is to render the whole techno post "cathodic" with an external anodic area. By so doing, the techno protection based on the cathodic protection principle brings the metal post in the "cathodic" state, thus securing it efficiently against degradation.