An overview of recent progresses in probing and understanding corrosion under disbonded coatings

ABSTRACT

Corrosion under disbonded coatings (CUDC) remains a major unsolved issue and a prime risk to underground steel structures such as buried gas pipelines. CUDC could not be effectively mitigated by conventional cathodic protection (CP) or be detected through usual inspection and survey technologies due to CP shielding. This article provides a brief review of recent progresses made through laboratory and field probing of CUDC and its influence factors. Discussions on CUDC processes and mechanisms are made based on results from an extensive laboratory and field-testing program using electrode array-based corrosion probes. It is shown that CUDC is affected not only by well-known factors such as the CP level, but also by coating disbondment geometry and soil conditions especially the seasonal dry-wet changes in soil saturation status. These findings have led to improved understanding of CUDC, and could lead to the development of better CUDC mitigation and control methods.

KEYWORDS:

• Localised corrosion
• corrosion monitoring
• corrosion under disbonded coatings
• pipeline corrosion
• electrochemical probe
• cathodic protection

Acknowledgements

The cash and in-kind support from the industry participants is gratefully acknowledged.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work is funded by the Energy Pipelines CRC and Future Fuels CRC, supported through the Australian Governments’ Cooperative Research Centres Program.