SYMPOSIA PAPER Published: 27 February 2019

Validation of Coated Infrastructure Examination by Electrochemical Impedance Spectroscopy


Field electrochemical impedance spectroscopy (EIS) measurement allows researchers and facility owners to examine protective coatings on existing infrastructure. Few other nondestructive coating inspection methods provide quantitative information, and none are as comprehensive. EIS measures the total resistance to water and ion permeation for the in-service coating, which indicates the degree of corrosion protection. A desired application of these results is to maximize coating service life and improve maintenance planning at facilities with valuable coated infrastructure. EIS evaluation of naturally aged coatings also offers the opportunity to advance coating service life prediction studies. Despite advances in hardware portability and progress in method development, however, field EIS testing and application to coating maintenance decision-making remain limited. The absence of a standardized procedure for conducting a field EIS survey and analyzing its results is a barrier to further implementation. This paper evaluates the repeatability of EIS measurements through an experimental design performed on coated infrastructure. The assessed structures varied from high-to-low protective impedance values, and the service environments were atmospheric and constant immersion. All coatings were approaching the end of their service life. The tests demonstrate outcomes for many of the variables encountered when executing the proposed field method, including coating type, thickness, age, and exposure conditions. The results show good repeatability for specimens, but variation occurs in the values obtained from one specimen to the next. The paper also considers EIS test method parameters, including applied frequency range and number of data points collected, as well as the practical challenges of performing field EIS testing. The discussion proposes the best practices realized through these studies, such as the use of a two-cell setup and the illustration of results via probability plots. Final thoughts highlight the future work necessary to advance standardization and implementation of field EIS testing.

Author Information

Merten, Bobbi, Jo E.
Bureau of Reclamation, Materials and Corrosion Laboratory, Denver Federal Center, Denver, CO, US
Walsh, Michael, T.
Bureau of Reclamation, Materials and Corrosion Laboratory, Denver Federal Center, Denver, CO, US
Torrey, Jessica, D.
Bureau of Reclamation, Materials and Corrosion Laboratory, Denver Federal Center, Denver, CO, US
Price: $25.00
Contact Sales
Reprints and Permissions
Reprints and copyright permissions can be requested through the
Copyright Clearance Center
Developed by Committee: G01
Pages: 137–159
DOI: 10.1520/STP160920170223
ISBN-EB: 978-0-8031-7664-5
ISBN-13: 978-0-8031-7663-8