Corrosion of steel occurs when steel is in direct contact with water and oxygen. In the special form “Corrosion under Insulation” – CUI for short, corrosion occurs at such a rate that the application of a protective barrier in the form of a coating system considerably extends the service life of exposed pipes, tanks and equipment (e.g. heat exchangers). The biggest corrosion under insulation takes place in a temperature range between 50 and 180°C. The most severe corrosion can occur in the heat exchangers.