The usability, lifetime and availability of many plants, especially in the oil & gas, pharmaceutical, chemical and petrochemical industries, are greatly determined by the resistance to corrosion of the materials used. In addition to the selection of materials for all individual components and the design and layout, there are numerous other influencing variables which are not very obvious. Slight modifications to the chemical composition of raw materials or additives, minimal deviations from optimum process conditions or minor external influences can trigger active corrosion processes, resulting in serious changes in product quality or damage to and availability of equipment.