The selection of inspection points is of paramount importance as corrosion factors to be considered in a corrosion maintenance program are often related to the geometry of systems and components. Selection of inspection points should be based on a thorough knowledge of process conditions, materials of construction, geometry of the system, external factors and historical records.
An example where an industrial concern is translated into an inspection program is with the loss of plant profitability due to production losses associated with boiler tube failures. Under-deposit corrosion in steam generating systems is caused or enhanced by the breakdown and/or inability to form a protective magnetite film. Production losses resulting from reduced steam capacity are far greater then the actual repair and maintenance costs incurred during shutdowns. The major contributors to the formation of deposits and scale are:
Accumulation of corrosion products mostly consisting of iron oxides introduced in the boiler from the feedwater and condensate systems
Contaminants present in the make-up water
Contaminants introduced to the condensate return from process equipment.
Solids introduced from leakages