Corrosive naphthenic acids and sulfur compounds in crude oils present a major challenge for refineries from a corrosion perspective. Although it is accepted that some sulfur compounds may form protective FeS scales on the metal surface and deter corrosion, attempting to correlate the characteristics of FeS scale with its protective properties has not been successful. Given the complex chemical compositions of real crudes, model sulfur compound and model naphthenic acids were used to mimic the corrosion by crude fractions in the present study. The iron sulfide scale formed by the model sulfur/acid compounds was challenged by naphthenic acids to examine its protectiveness against corrosion. Moreover, the scale was analyzed with TEM/EDS technique and a layer of iron oxide was found when naphthenic acids were present in the solution. The iron oxide layer appeared to be important for maintaining protection against naphthenic acid corrosion and further analysis revealed that it was composed of magnetite.

Subject
Energy dispersive X-ray spectroscopy, Naphthenic acid, Corrosion rate, Oils, Iron sulfides, Oxide layers, Corrosion scales, Pretreatment, Solutions, Scale formation, Steel, Crude, Corrosion protection
Keywords:
naphthenic acids, iron sulfide scales, iron oxide, high temperature corrosion, crude fractions, model sulfur compounds
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2014
Association for Materials Protection and Performance (AMPP)
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