Corrosion is an electro chemical reaction that occurs if the coating gets damaged even in a small area or if it develops cracks or if the thickness of the coating is not adequate. The metal pipeline, thus exposed to soil or water, will form two electrodes of opposing polarity (anodes and cathodes) on the same metal. This may be due to chemical composition, velocity, temperature, stress or impurities in the metal. The electrical potential difference between these newly formed anodes and cathodes

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... gives rise to a current that causes the pipe line to lose metal and become leaky. The corrosion develops and begins to spread, causing enormous damage to property as well as environment. The loss due to Corrosion has been estimated to be of the order of 2 - 5% of the Gross National Product (GNP) of any Country.