Appropriate levels necessary for reduction of corrosion

Corrosion simply stated is an electrochemical reaction by which a metal due to its environment oxidizes and returns to the ore it was derived from. This electrochemical reaction occurs on gas piping when it is exposed to varying compositions of soil, moisture and oxygen. The use of isolation devices, dielectric coatings, and supplemental cathodic protection is a successful method of controlling corrosion on the exterior surface of buried or submerged metallic piping structures. Isolation devices are used to electrically separate piping or other structures from the piping that is to be protected from corrosion. The cost of corrosion control is reduced and its effectiveness improved. This paper reviews methods for determining the level of cathodic protection needed and methods for applying it. It addresses the different sources of current available.