Corrosion problems and corrosion control. 7 Cathodic protection.

Corrosion and Cathodic Protection Theory

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Cathodic Corrosion Protection of earthburried Pipelines

Corrosion and Cathodic Protection in Underground Piping Systems

THE GALVANIC CELL The major corrosion concern in the water works industry is “galvanic” corrosion. Galvanic corrosion takes place due to current flow in a “galvanic cell” which is defined as (1) two dissimilar metals, an anode and a cathode, (2) in electrical contact with each other and (3) a common electrolyte. A galvanic cell is produced when the pipeline components come in contact with the s...

VIII-Metals-J-Corrosion protection-1_ CORROSION PROTECTION OF METALS

Nearly all metals, with the exception of gold and platinum, will corrode in an oxidising environment forming compounds such as oxides, hydroxides and sulphides. The degradation of metals by corrosion is a universal reaction, caused by the simple fact that the oxide of a metal has a much lower energy than the metal itself. Hence there is a strong driving force for the oxidation of metals. For ex...

Coatings and Cathodic Protection for Underground Pipelines - What a Corrosion Engineer Should Know

Coatings control corrosion by providing a barrier against oxygen and water. Although coatings are extremely effective, all organic coatings are semi-permeable to O2 and water. The water permeability coefficient of fusion bonded epoxies, one of the best coating systems, is approximately 10 gms/mil/24 hours, but minimum concentration of oxygen and water that can start the corrosion process is 10 ...