Effect Of Steel Microstructure And Corrosion Product Characteristics On Inhibition Performance Of Decanethiol Against TLC

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Product Number: 51321-16581-SG

Author: Z. Belarbi/ F. Farelas/ D. Young/M. Singer

Publication Date: 2021

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The use of corrosion inhibitors to control top of the line corrosion (TLC) of steels exposed to CO2 environments is common in the oil and gas industry. The performance of such chemicals depends on the physical nature of the steel surface and the stability of corrosion product layers. The objective of this work was to investigate and understand the role of steel microstructure (pearlitic-ferritic and tempered martensitic) and the state of a pre-corroded surface, specifically the effect of FeCO3 and Fe3C corrosion product layers on the inhibition performance of decanethiol at TLC conditions. Weight loss measurements and Fe2+ concentration in condensed water were used to measure the corrosion rate in the absence and presence of decanethiol. Scanning electron microscopy (SEM) coupled with energydispersive X-ray spectroscopy (EDS) were used to characterize the morphology and chemical composition of the surface. After the removal of the corrosion products, profilometry was performed to assess the occurrence of localized attack. The acquired data showed that the steel microstructure and the nature of the corrosion product layer affect the inhibition performance of decanethiol in a CO2 environment. The presence of a FeCO3 layer decreased the inhibition efficacy of decanethiol (95 to 82%). In contrast, the presence of a Fe3C layer did not affect the inhibition efficacy of the tested chemical. An inhibition mechanism was also proposed based on the physical proprieties and the nature of the surface.

Keywords: CO2 corrosion, iron carbonate, top of the line corrosion, decanethiol, cementite, scale