Skip to Main Content
 

Global Search Box

 
 
 

ETD Abstract Container

Abstract Header

Top of the Line Corrosion in CO2/H2S Environments

Abstract Details

2015, Doctor of Philosophy (PhD), Ohio University, Chemical Engineering (Engineering and Technology).
Top of the line (TLC) corrosion in sour (H2S) environments has not been well understood until now, since most reported TLC research has focused on sweet (CO2) conditions, with various models developed to predict corrosion rates and related phenomena in sweet systems. This has led to many unanswered questions relating to TLC mechanisms in CO2/H2S environments. In most sour environments, the nature of the FeS corrosion product layer is dependent on the concentration of H2S present in the mixed CO2/H2S environment. Therefore, the intent of this research is to determine the TLC behavior in marginally (less than 1 mbar/1000 ppm of H2S) and highly sour environments (more than 10 mbar/10000 ppm H2S), since both described conditions would lead to different TLC mechanisms. Experiments were conducted in custom designed autoclaves. Weight loss method for corrosion rate measurement, corrosion product analysis by SEM/EDX, optical profilometry, and condensed water analysis were used to investigate the TLC mechanisms. In marginally sour TLC between 0.015 mbar (15 ppm) to 0.03 mbar (30 ppm H2S), a non-homogenous FeS layer formed on the steel surface in shorter experiments (lasting a few days), with some areas being covered and others not. This localized corrosion which was not sustained, since pits were not seen in longer experiments lasting 28 days. Increases in H2S concentration between 0.08 mbar (80 ppm) to 0.15 mbar (150 ppm) did not lead to initiation of localized corrosion. The steel surface was uniformly covered by an FeS layer due to the greater scaling tendency that overcame the undermining by corrosion. Low general corrosion rate were found. Increase in water condensation rate lead to higher TLC rate due to saturation limits with respect to aqueous species required for formation of both FeCO3 and FeS, phases that can confer a degree of protection against corrosion. In highly sour TLC, the main parameter which controls TLC behavior is the characteristics of the FeS layer formed on the steel surface. The formation of more coherent FeS layers was observed at higher steel temperature and conferred greater protectiveness regardless of the water condensation rate which is the main controlling factor in sweet TLC. Water condensation rate acts as a secondary effect that lowers the steel temperature. Finally, the TLC corrosion mechanisms in CO2/H2S environments (marginally and highly sour) were proposed through a descriptive model approach.
Srdjan Nesic (Advisor)
198 p.

Recommended Citations

Citations

  • Yaakob, N. (2015). Top of the Line Corrosion in CO2/H2S Environments [Doctoral dissertation, Ohio University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1427716457

    APA Style (7th edition)

  • Yaakob, Najmiddin. Top of the Line Corrosion in CO2/H2S Environments. 2015. Ohio University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1427716457.

    MLA Style (8th edition)

  • Yaakob, Najmiddin. "Top of the Line Corrosion in CO2/H2S Environments." Doctoral dissertation, Ohio University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1427716457

    Chicago Manual of Style (17th edition)