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S&T Project 1884 Final Report: Field Validation of Impedance Spectroscopy Coating Assessments

Field demonstrations to advance the test method occurred at the Green Mountain Powerplant, Salt River Siphon, the Agua Fria River Siphon, and Fontana Dam. Laboratory experiments investigated the impact of modified test set ups for field EIS, the accuracy of the available field potentiostats, and an approach for extrapolating long-term laboratory EIS data to aid estimation of remaining service life for field EIS data. The research found the following: 1) Good agreement between the field EIS data and the corresponding laboratory data; 2) Improvements to the recommendations for the field EIS test method, including a testing plan for large structures and approaches for testing non-horizontal surfaces, that is in the process of standardization for international applications via ASTM International work group WK67789; 3) No effect of the distance between test cells on the accuracy of field EIS data; 4) No effect on results of the coupling of the reference and countered electrode compared to the traditional set-up having unique electrodes for each; 5) Recommendations for usage of the Ivium CompactStat for field EIS testing and limited usage of the Ivium PocketSTAT, pending further investigation of its accuracy with resistors less than 10^9 ohms; 6) A first approximation for an approach to determining the remaining service life of a coating in the field based on laboratory data for the same coating system. The recommended next steps are to continue the refinement of the field EIS testing method and the understanding of EIS data in its relationship to the coating’s remaining service life. The standardization of the method, if successful, would allow for inclusion of the test method in coating specifications to ensure a good product is received. Further investigation into the use of the PocketSTAT for investigating lower impedance coatings and coatings nearing the end of their service life is recommended.
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Generation Effort S&T Project Number 1884: Field Validation of Impedance Spectroscopy Coating Assessments
Type Uploaded file(s)
File Type PDF
Publisher Bureau of Reclamation
Publication Date Tuesday, September 29th, 2020
Update Frequency not planned
Last Update Wednesday, October 28th, 2020


The findings and conclusions of this work are those of the author(s) and do not necessarily represent the views of the Bureau of Reclamation.