1. Introduction
Corrosion is the degradation of a metal or alloy, as a result of chemical reaction with its environment. The degradation is caused by an oxidation reaction, In electrochemical sense, oxidation is metal atom (M) losing electrons. (Not necessarily to Oxygen).
M → M + e
By the corrosion attack of any type, component can weaken. The rate and nature of attack is influenced by mechanical stress, thermal stress, cyclic stress, temperature, type of environment, type and nature of corrosion product formed, etc. Since the parameters are at large and can vary, it is difficult to predict the corrosion behavior. The harm to the life of the component also depends on the type of corrosion attack Pitting type-localized corrosion may puncture the container earlier than a uniform corrosion. And the spalled corrosion product debris of uniform corrosion may choke the inside of heat exchanger. threatening its life.