When can Electrochemical Techniques give Reliable Corrosion Rates on Carbon Steel in Sulfide Media?

Lisbeth Rischel Hilbert, Tor Hemmingsen, Lars Vendelbo Nielsen, Sonja Richter

    Research output: Chapter in Book/Report/Conference proceedingArticle in proceedingsResearchpeer-review

    Abstract

    Effects of film formation on carbon steel in hydrogen sulfide media may corrupt corrosion rate monitoring by electrochemical techniques. Electrochemical data from hydrogen sulfide solutions, biological sulfide media and natural sulfide containing geothermal water have been collected and the process of film formation in sulfide solutions was followed by video. It can be shown that capacitative and diffusional effects due to porous reactive deposits tend to dominate the data resulting in unreliable corrosion rates measured by electrochemical techniques. The effect is strongly increased if biofilm in combination with ferrous sulfide corrosion products cover the steel surface. Corrosion rates can be overestimated by a factor of 10 to 100 with electrochemical techniques - both by linear polarization resistance (LPR) and electrochemical impedance spectroscopy (EIS). Oxygen entering the system accelerates corrosion rates, but this effect may not be detected if rates are already overestimated. It is concluded that electrochemical techniques can be used for corrosion rate monitoring in som hydrogen sulfide media, but care must be taken when choosing the scan rates, and it is important to realize when direct techniques like electrical resistance or mass loss should be used instead.
    Original languageEnglish
    Title of host publicationCorrosion2005
    Publication date2005
    Publication statusPublished - 2005
    EventCorrosion 2005 - Houston, TX, United States
    Duration: 3 Apr 20057 Apr 2005
    http://www.imp.edu.pl/corrosion2005/

    Conference

    ConferenceCorrosion 2005
    CountryUnited States
    CityHouston, TX
    Period03/04/200507/04/2005
    Internet address

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