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Cathodic Protection (CP) is a technology that uses direct electrical current to counteract or neutralize the normal external corrosion of a metal pipeline. The change from the metallic to the combined form occurs by an “anodic” reaction. This reaction produces free electrons, which pass within the metal to another site on the metal surface (the cathode), where it is consumed by the cathodic reaction. Corrosion thus occurs at the anode but not at the cathode (unless the metal of the cathode is attacked by alkali). CP is used where all or part of a pipeline is buried underground or submerged in water. Cathodic protection can be achieved in two ways; by the use of galvanic (sacrificial) anodes, or by ‘impressed’ current. Coatings are applied to pipelines whether above or below ground and often are used in combination with cathodic protection.