Use of Magnesium Anodes in Cathodic Protection of Tanks and Pipelines

Abstract

protection. Several methods of applying cathodic protection have been devised, among them being use of the galvanic anode. Galvanic anodes were first introduced by Sir Humphry Davy in 1823, when he suggested the use of zinc anodes for the protection of ship bottoms. Since that time, many metals have been used, with magnesium being among the most successful for mitigating steel corrosion. It has long been known that when two dissimilar metals are placed in a common electrolyte and connected electrically, a current will flow between them. Such a system is known as a galvanic cell. Every metal has a definite tendency to dissolve, or go into solution, when placed in a given electrolyte. This tendency is technically referred to as a solution potential. When two metals having different solution potentials ,are connected in a common electrolyte, the metal with the greater potential will dissolve preferentially and, in so doing, will inhibit the solution of the metal having the lesser potential. Electrochemically, the ions liberated by the dissolving particles of the metal having the higher solution potential (the anode) form an electric current which flows through the electrolyte to the metal having the lower solution potential (the cathode). This current acts to inhibit the solution of the