The most common cause for metal structure failure has been discovered to be 'corrosion'. It has been discovered that, rate of corrosion is much faster in acidic than alkaline medium. Once the corrosion of metal is started it starts deteriorating the properties of metal like ultimate tensile strength, toughness, hardness, ductility etc. . Corrosion is a most challenging and expensive problem in many sectors. Corrosion professionals, asset owners and coating formulators are still focused on understanding and lowering the cost of corrosion and mitigating its effect on the life of structure . Based on to atmospheric exposure conditions corrosion is classified as wet corrosion and dry corrosion and based on mechanism of corrosion, it can be classified in different types; some of them are, uniform corrosion, stress corrosion, galvanic corrosion, crevice corrosion, pitting corrosion, inter-granular corrosion, erosion corrosion and water line corrosion .