Abstract
The behavior of a coal tar, a polyethylene, and a fusion bonded epoxy was evaluated. Coated samples with and without intentional failures exposing the metallic substrate were submitted to different levels of cathodic polarization. The process of delamination was monitored with current and impedance measurements. The delamination was quantified by a standard method. No quantitative relationship between the delaminated areas and electrochemical parameters could be found; the reasons are discussed in terms of the properties of the coatings. It was shown that the higher the dielectric strength of coatings, the more critical the role of pores and mechanical damage in determining cathodic protection effectiveness.
Similar content being viewed by others
References
NACE Standard RP-01-69, “Recommended Practice for Control of External Corrosion on Underground or Submerged Metallic Piping Systems,” NACE International, 1983 Revision.
Mansfeld, F., Lee, C.C., and Zhang, G., “Comparison of Electrochemical Impedance and Noise Data in the Frequency Domain,”Electrochim. Acta, 43 (3–4), 435 (1998).
Beaunier, L., Epelboin, I., Lestrade, J.C., and Takenouti, E.H., “Electrochemical; Study with a Scanning Electron Microscope of Paint Coated Iron,”Surf. Technol., 4, 237 (1976).
van Westing, E.P.M. “Determination of Coating Performance with Impedance Measurements,” TNO Centre for Coatings Research, Delft, The Netherlands (1992).
Mansfeld, F., “Use of EIS for the Study of Corrosion Protection by Polymer Coatings,”Appl. Electrochem., 25 (3), 187 (1995).
Bonora, P.L., Deflorian, F., and Fedrizzi, E.L., “Electrochemical Impedance Spectroscopy as a Tool for Investigating Underpaint Corrosion,”Electrochim. Acta, 41 (7/8), 1073 (1996).
Margarit, I.C.P. and Mattos, O.R., “About Coatings and Cathodic Protection: Possibilities of Impedance as Monitoring Technique,”Mat. Sci. Forum, 289–292, 279 (1998).
Margarit, I.C.P. and Mattos, O.R., “About Coatings and Cathodic Protection: Properties of the Coatings Influencing Delamination and Cathodic Protection Criteria,”Electrochim. Acta, 44 (2–3), 363 (1998).
Taves, J., Quintela, J., and Machado, I., “Bolivia-Brazil Gas Pipeline—New Coating Technology Approach,” 11th International Conference on Pipeline Protection, BHR Group Conference Series, Wilson, A. (Ed.), Publ. no 16, 91 (1995).
“Standard Test Methods for Cathodic Disbonding of Pipeline Coatings, ASTM G8-92,” American Society for Testing and Materials.
Quintela, J.P., de Oliveira, R.C.A., Margarit, I.C.P., and Mattos, O.R., “Organic Coated Steel Submitted to Cathodic Protection Studied by Electrochemical Methods,”Mater. Sci. Forum, Ferreira, M.G.S. and Simões, A.M.P. (Eds), 192–194, 305 (1995).
Hirayama, R. and Haruyama, S., “Electrochemical Impedance for Degraded Coated Steel Having Pores,”Corrosion, 47 (12), 952 (1991).
Haruyama, S., Asari, M., and Tsuru, T., “Impedance Characteristics During Degradation of Coated Steel,”Proc. Symp. Advances in Corrosion Protection by Organic Coatings, Kendig and Leidheiser (Eds.), The Electrochemical Society, Vol. 87–2, 197, 1986.
Author information
Authors and Affiliations
Additional information
EE/COPPE/PEMM, P.O. Box 68505, 21945-970 Rio de Janeiro, Brasil; omattos@metalmat.ufrj.br; Cidade Universitária, Rio de Janeiro.
Rights and permissions
About this article
Cite this article
Margarit, I.C.P., Mattos, O.R., Ferreira, J.R.R.M. et al. About coatings and cathodic protection: Electrochemical features of coatings used on pipelines. Journal of Coatings Technology 73, 61–65 (2001). https://doi.org/10.1007/BF02698439
Issue Date:
DOI: https://doi.org/10.1007/BF02698439