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Understanding the electrochemical processes at the interface of cathodically protected steel pipeline and soil during anodic transients

conference contribution
posted on 01.01.2018, 00:00 authored by Yafei Zhang, Bruce HintonBruce Hinton, Bob VarelaBob Varela, Maria ForsythMaria Forsyth, Mike Yongjun TanMike Yongjun Tan
The steel/soil interface on cathodically protected pipeline steel has been investigated using electrochemical polarisation measurements and electrochemical impedance spectroscopy, to add more insights into the electrochemical processes occurring at the interface. A critical electrode potential (CEP) was found that divides the steel corrosion reaction kinetics into two regions. When the electrode potential is below this critical value, the steel surface has a large impedance value, indicating much slower corrosion kinetics than when the electrode potential is more positive than the CEP value. This critical value is found to be related to pitting potential determined by potentiodynamic polarisation measurements. The CEP could be affected by the CP condition and environmental, including the CP potential and the soil moisture content. At a more negative CP potential, the CEP was found to be nobler; while at the same CP potential but in the soil with a higher moisture content, the CEP became more negative. The impact of the CP potential and soil moisture level on the CEP value is explained by local soil pH effects on steel passivity.

History

Event

Coatings and Corrosion. Symposium (2016 : Kuala Lumpur, Malaysia)

Volume

53

Issue

7

Series

Coatings and Corrosion Symposium

Pagination

517 - 523

Publisher

Taylor & Francis

Location

Kuala Lumpur, Malaysia

Place of publication

Abingdon, Eng.

Start date

16/05/2016

End date

19/05/2016

ISSN

1478-422X

eISSN

1743-2782

Language

eng

Publication classification

E Conference publication; E1 Full written paper - refereed

Copyright notice

2018, Institute of Materials, Minerals and Mining Published by Taylor & Francis on behalf of the Institute

Editor/Contributor(s)

J Ching, P Sook Wai

Title of proceedings

ISCC2016 : Sustaining technical integrity through improved coating industry and corrosion protection technologies : Proceedings of the International Symposium on Coatings and Corrosion 2016