Mike YJ Tan, Institute for Frontier Materials and School of Engineering, Deakin University

1. An Overview of Research Conducted for the EPCRC on Assessing the Performance of Coating & Cathodic Protection Mike YJ Tan, Institute for Frontier Materials and School of Engineering, Deakin University

2. Major Research Projects

3. New findings on anodic transient effects on CP: New concepts of critical duration and amplitude of anodic transientsYing Huo and Mike TanIndustry advisors: Alan Bryson, Brian Martin, Bruce Ackland and Geoff Cope

4. Pipeline corrosion problems could be caused by anodic transients 1000mV 450mV Urban area Rural area The pipeline industry needs to know exactly how ‘big' these anodic transients (either in magnitude or length or frequency) need to be to cause a major pipeline corrosion problem.

5. These are unanswered questions Reference: AS2832.1 (Cathodic protection of metals: Pipes and cables).

6. Main Findings • There is a critical anodic transient duration that implies the allowable “safe” duration for single anodic transients on the cathodically protected buried steel. • Typical critical anodic transient durations for steel exposed to a constant anodic transient amplitude of 1000mV under CP of -950mVvs.CSE, were found to be approximately 9 minutes in 1000Ω.cm resistivity sandy soil.

7. Snapshot of data showing ‘critical duration’ of anodic transients

8. Snapshot of data showing ‘critical amplitude’ of anodic transients

9. Explaining the critical anodic transient duration 24 hour CP State 1 Anodic transient General corrosion zone Passive layer 2 3 4 State 2 pH reducing 1 Passive layer break down State 3

10. New findings on cathodic shielding (CP current shielding by coatings)Mauricio (Max) Latino, Bob Varela and Mike TanIndustry advisors: Alan Bryson, Bruce Ackland, Geoff Cope, Brian Martin, Jan Lim

11. Key findings • A high local pH has been confirmed to be a key to prevent corrosion under disbonded coatings. • Most of commercial coatings shielded CP, however some thin epoxy coatings allow CP current permeation, affecting local pH under disbonded coatings. • Coating’s aging, disbondment dimension, gap size and soil saturation status have been found to affect corrosion under disbonded coatings.

12. Research issues on cathodic shielding and corrosion under disbonded coatings

13. General findings

14. HDD Pipelines - Coating Integrity and CP Efficiency Ying Huo and Mike TanIndustry advisors: Alan Bryson, Brian Martin, Bruce Ackland and Geoff Cope

15. Horizontal directional drilling (HDD) pipelines and coating damages Obstacles HDD pipeline Coating defects Sharp rock Pull

16. HDD Pipelines – quantifying coating integrity and CP efficiency Laboratory sand box simulation of HDD pipelines in order to evaluate the performance of existing testing methods for detecting coating defects, and to develop better methods for more accurate determination of coating defects (e.g. numbers, sizes and distributions). Currently there are technical difficulties in accurately assessing HDD pipe coating damage and CP efficiency, and as a consequence the integrity and durability of HDD pipes could not be assured.

17. Findings and results • Both the ‘on potential swing method’ and ‘off potential method’ have shown significant uncertaintiesinmeasuring coating damage areas. • A new EIS method has been developed based on the fact that capacitance values correlate better with coating damaged areas and it is non-destructive. • A new local measurement method has been proposed and has shown to be able to detect coating defect locations.

18. Off potential method: defect size Cathodic current density (mA/cm2) 1 cm x 1 cm 3 cm x 3 cm 10 cm x 10 cm Defect area (cm2)

19. On potential swing method: defect size Cathodic current density (mA/cm2) 1 cm x 1 cm 3 cm x 3 cm 10 cm x 10 cm Defect area (cm2)

20. EIS method: Capacitance of defects Capacitance (F) Size of defect (cm2)

21. Neutralized defect capacitance

22. A new local EIS measurement method 2.5cm x 44cm171cm – 215cm 2.5x44 No defect

23. Trying to apply local EIS on HDD pipeline in the field

24. Corrosion monitoring probes and IT platform development Facundo Varela, Ke Wang, IndivarieUbhayaratne, Mike YJ. TanIndustry advisors: Alan Bryson; Bruce Ackland; Brian Martin; Geoff Cope; Alireza Kouklan; Nick Doblo; Mark Dragar; Eric Jas

25. Pipeline condition monitoring probes & software

26. A sample probe installation

27. Sample results

28. Sample findings ● At the gas pipeline CP potentials, metal losses were low for all locations. At less negative CP potentials, metal losses were significantly higher . ● At the coating disbondment, soil moisture level, dry/wet weather, and air gaps at coating disbondment have found to affect corrosion significantly. They appear to be more important than the level of CP applied.

29. These field tests valid probe characteristics such as, ●The probes perform in-situ corrosion monitoring without CP interruption. ● The probes monitor corrosion without the need of an accurate knowledge of the CP potential applied or the chemistry of the soil environment. ● The probes allow to inexpensively in-situ evaluate corrosion rates, with higher sensitivity than current methods.

30. Analysis, modelling and display of corrosion monitoring data

31. Acknowledgements • This work was funded by the Energy Pipelines CRC, supported through the Australian Government’s Cooperative Research Centres Program. The funding and in-kind support from the APGA RSC is gratefully acknowledged • Industry Advisers, in particular Alan Bryson, Geoff Callar, Brian Martin, Bruce Ackland, Geoff Cope, Alireza Kouklan; Craig Bonar, Mark Dragar and Huw Dent for their advice and comments on our research proposal and on this work.