Inhibition of CO2 corrosion of mild steel − Study of mechanical effects of highly turbulent disturbed flow. (September 2017)

• Record Type: Journal Article
• Authors: Li, Wei; Pots, B.F.M.; Zhong, Xiankang; Nesic, Srdjan
• Is Part Of: Corrosion science. Volume 126(2017)
• Page Start: 208
• Page End: 226
• Publication Date: 2017-09
• Subjects: Acid inhibition -- Mild steel -- Wall shear stress -- Cavitation -- Polarization -- Weight loss -- SEM -- CFD; Corrosion and anti-corrosives -- Periodicals; 620.11223
• DOI: 10.1016/j.corsci.2017.07.003
• Languages: English
• ISSNs: 0010-938X

Abstract

Highlights: In the present study, there was no evidence of inhibitor failure due to high wall shear stress (up to 5000 Pa). In the presence of the inhibitor (at 72 ppmv ), severe pitting corrosion occurred in disturbed flow, which was caused by cavitation of condensable water vapor bubbles. Using an excess amount of inhibitor (720 ppmv ), this pitting corrosion was mitigated. The observed behavior can be readily explained in terms of the kinetics of inhibitor adsorption/desorption and the associated activation energy analysis. Abstract: The failure mechanisms of corrosion inhibitors in highly turbulent flow remain a disputed topic. In the present study, corrosion experiments of X65 pipeline steel were performed with an imidazoline-based corrosion inhibitor using a high-shear turbulent channel flow cell, which included a flow disturbance in the form of a small protrusion. Localized corrosion was observed at the protrusion that could be mitigated with an excess inhibitor concentration. It was found that wall shear stress (up to 5000 Pa) was not the cause of inhibitor failure. The flow acceleration at the leading edge of the protrusion caused a drop in pressure and led to cavitation, with bubble collapse further downstream. This was the main cause of inhibitor failure and localized corrosion. The observed behavior was interpreted in terms of corrosion inhibitor adsorption/desorption kinetics and the associated activation energy analysis.