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Journal of Materials Science

, Volume 42, Issue 24, pp 9940–9946 | Cite as

Passivity breakdown of carbon steel in hot potassium carbonate solutions

  • S. J. Harjac
  • A. Atrens
  • C. J. Moss
  • V. Linton
Article

Abstract

This research studied passivity breakdown of carbon steel in conditions typical of hot potassium carbonate (HPC) acid gas processing plants. The pitting potential, evaluated from polarisation curves, indicated resistance to pitting increased with increasing equivalent carbonate concentration. The pitting potential was much more positive than the free corrosion potential for uninhibited concentrated carbonate solutions with pH values of 8.5 to 9.5. Therefore pitting is not an issue in these solutions. However, the carbon steel was susceptible to pitting corrosion in the dilute 1.0% bicarbonate solution of pH 8.0 for chloride concentrations in excess of 0.5 wt%. The critical chloride concentration was considerably above the maximum concentration of 0.1 wt% recorded in a typical HPC plant. Consequently chlorides should not usually be of concern to plant integrity.

Keywords

Chloride Concentration Passive Film Passive Layer Thiosulphate Free Corrosion Potential 

Notes

Acknowledgements

The support of Santos for this work and permission to publish this article is gratefully acknowledged. Thank you to P. Wilson, of Corrosion Risk Management Pty Ltd, for his work on developing the pH model, Porbaix Diagram and his technical advice.

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Copyright information

© Springer Science+Business Media, LLC 2007

Authors and Affiliations

  • S. J. Harjac
    • 1
  • A. Atrens
    • 1
  • C. J. Moss
    • 2
  • V. Linton
    • 3
  1. 1.Materials, School of EngineeringThe University of QueenslandBrisbaneAustralia
  2. 2.Santos LtdAdelaideSouth Australia
  3. 3.School of Mechanical EngineeringThe University of AdelaideAdelaideSouth Australia

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