Industrial Methods of Preventing Galvanic Corrosion: Part II
This chapter discusses two more industrial methods of preventing galvanic corrosion, cathodic protection (CP) and anodic protection (AP). CP systems are used to protect various metallic structures in different environments, for example, steel water or fuel pipelines and steel storage tanks, ship and boat hulls, offshore oil platforms, and metal reinforcement bars in concrete buildings and structures. CP transformer-rectifier units used in water tanks and also used in other applications are made with solid-state circuits. Pipelines carrying dangerous products are protected by a protective coating, followed by CP. The use of CP for concrete reinforcement is slightly different. In concrete reinforcement, the anodes and reference electrodes are generally embedded in the concrete at the time of construction during the pouring of concrete. AP is used to protect metals that exhibit passivation in environments. The current density in the freely corroding state could be significantly higher than the current density in the passive state over a wide range of potentials.