The Mechanism of Corrosion–Erosion in Steam Extraction Lines of Power Stations

Abstract

Corrosion-erosion occurs in steam extraction piping made of low carbon steel that conveys wet steam. The rate of metal removal peaks at 150°C and is most severe on the inside and outside of bends and in the vicinity of fittings. A theory is presented by which three processes are shown to give rise to the observed peak in the metal removal rate: (1) the oxidation reaction, (2) the mass transfer process, which governs at 150°C, and (3) the diffusion resistance of the oxide layer, which governs at higher temperatures. The results of the derived model agree well with the available experimental data in predicting wear rates and in establishing the temperature and the location of maximum material removal.