Corrosion is defined as the chemical or electrochemical reaction between a material, usually a metal, and its environment that produces a deterioration of the material and its properties. So the result of corrosion is metal loss.
Metals extracted from their ores are in high energy states. Thermodynamically, the higher energy state is not stable. Corrosion is a natural occurring process, predicted by thermodynamics laws. Thermodynamically, Corrosion is defined as the spontaneous transition of metal from the higher energy state to the lower energy state in which the higher energy state is the metal and the lower energy state is the metallic compound.The lower energy state may or may not be same as their ore.
In the oil and gas pipelines with steel as the pipe material, the principle corrosion products formed in the presence of different elements (say for example oxygen, chlorine, sulphur and carbonates) are Fe(OH)2, Fe2O3, FeO, FeCl2, FeS, FeCO3 etcetera. With aluminum, the principle corrosion products formed are Al2O3.
