A Critical Survey of Possible Factors Contributing to Internal Boiler Corrosion

Abstract

Main factors contributing to boiler corrosion are reviewed. Published data and work at authors’ laboratories on the following causes of boiler pitting and corrosion are reviewed and discussed: Dissolved oxygen, copper deposition, concentration of sodium hydroxide, phosphate hideout, suspended solids, chlorides, thermal effects, thermogalvanic effects, break-down of magnetite films from cyclic expansion and contraction, strain, weld and tube defects, compositional inhomogeneities. Authors believe caustic and chloride attacks are mutually exclusive but that they may be found in combination with others. Changes in attitude about magnetite caused by recent discoveries indicate that radical concept changes can be expected.