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Mechanism and Prediction of Mild Steel Corrosion in Aqueous Solutions Containing Carboxylic Acids, Carbon Dioxide, and Hydrogen Sulfide

Kahyarian, Aria
http://orcid.org/0000-0001-8809-1493
http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1541154736282768

Abstract Details

2018, Doctor of Philosophy (PhD), Ohio University, Chemical Engineering (Engineering and Technology).
Pipeline corrosion in upstream oil and gas production and transmission facilities is a major design and maintenance concern. Corrosion in such environments is, to the most part, the results of the presence of an aqueous phase containing weak acids such as carboxylic acids, carbonic acid, and hydrogen sulfide. The proper understanding of encountered corrosion processes and reliable predicted corrosion rates are essential for major design decisions relating to material selection, pipe wall thickness allowance and adoption of appropriate maintenance procedures, such as use of corrosion inhibitors and frequency of in-line inspections. The health, safety, and environmental impact of possible failures and the significant economic burden of maintenance has been the driving force for the better understanding of corrosion mechanisms and more accurate and reliable corrosion rate predictions. The present study is focused on improving the mechanistic understanding of the corrosion process in such environments and further use of the developed knowledge to improve the prediction of corrosion rate. In this regard, the fundamental mechanisms of corrosion in the presence of all the major corrosive species, specifically, carboxylic acids, carbonic acid, and hydrogen sulfide, are discussed. In contrast to the commonly accepted corrosion mechanisms involving these species, the findings in the present study suggest that they are not directly reduced during the corrosion process. The high corrosivity of such environments was therefore determined to be the result of their chemical dissociation at the vicinity of the metal surface that acts as an additional source for hydrogen ions. The findings of the present study showed that corrosion of mild steel in such environments is in fact a much simpler process than it was believed previously, and in electrochemical sense it is no different from steel corrosion in acidic solutions. That is of great significance, both in terms of the general understanding of the corrosion process and also in terms of developing mechanistic corrosion rate predictive models. These models commonly use experimental data obtained in laboratory settings for calibration and are expected to reasonably predict the behavior of such systems in much harsher and more complex conditions encountered in industrial environments. Since extrapolation is an inherent part of such calculations, these models are only as reliable as the accuracy of their mechanistic foundations. Ultimately, the mechanistic findings of this study were used to propose a unified perspective into corrosion in the presence of weak acids to serve as a framework for other similar corrosion scenarios with any weak acid that might be present in the solution.
Srdjan Nesic, Dr. (Advisor)
Marc Singer, Dr. (Committee Member)
John Staser, Dr. (Committee Member)
Dina Lopez, Dr. (Committee Member)
Howard Dewald , Dr. (Committee Member)
433 p.
Chemical Engineering
Corrosion; mild steel; oil and gas; acidic; carbon dioxide; hydrogen sulfide; acetic acid; carboxylic acid; modeling; electrochemcial; polarization; corrosion rate prediction

Recommended Citations

Citations

  • Kahyarian, A. (2018). Mechanism and Prediction of Mild Steel Corrosion in Aqueous Solutions Containing Carboxylic Acids, Carbon Dioxide, and Hydrogen Sulfide [Doctoral dissertation, Ohio University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1541154736282768

    APA Style (7th edition)

  • Kahyarian, Aria. Mechanism and Prediction of Mild Steel Corrosion in Aqueous Solutions Containing Carboxylic Acids, Carbon Dioxide, and Hydrogen Sulfide. 2018. Ohio University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1541154736282768.

    MLA Style (8th edition)

  • Kahyarian, Aria. "Mechanism and Prediction of Mild Steel Corrosion in Aqueous Solutions Containing Carboxylic Acids, Carbon Dioxide, and Hydrogen Sulfide." Doctoral dissertation, Ohio University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1541154736282768

    Chicago Manual of Style (17th edition)

ohiou1541154736282768
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This open access ETD is published by Ohio University and OhioLINK.