Protection of stainless steel in hydrochloric acid solution containing hydrogen sulfide by inhibitors

• Ya.G. Avdeev¹, L.V. Frolova², D.S. Kuznetsov², M.V. Tyurina¹ and M.A. Chekulaev¹

¹ K. E. Tsiolkovsky Kaluga state university, 248023 Kaluga, Russian Federation
² A. N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, Leninskii pr. 31, Moscow, 119071 Russian Federation

Abstract: Corrosion of chromium-nickel steel 1Kh18N9T in 2 M HCl at t = 20–100°C was studied using the mass loss method. In parallel, hydrogen absorption by steel in the corrosive medium was measured by vacuum extraction method. IFKhAN-92 (a 1,2,4-triazole derivative) and its combination with urotropine were studied as corrosion inhibitors for stainless steel. It was shown that chromium-nickel steel 1Kh18N9T has low corrosion resistance in HCl solutions, particularly at temperatures close to 100°C. Under the conditions studied, the metal corrosion rate is k = 0.42–275 g/(m²·h) and increases with an increase in t. However, resistance of stainless steel to hydrogen absorption was noted. Addition of 15 mM H2S to the HCl solution considerably accelerates the corrosion of chromium-nickel steel (k = 3.2–800 g/(m²·h)) and causes strong hydrogen absorption. The highest content of hydrogen absorbed in the metal (24 ml/100 g) was observed at t = 40°C and 2 h exposure of the specimens. Longer exposures of steel specimens in the corrosive medium increase hydrogen absorption by the metal. Addition of IFKhAN-92 or a formulation of IFKhAN-92 with urotropine (at 1: 4 molar ratio of the components) provides efficient inhibition of steel corrosion in hot HCl solutions (t = 80–100°C). Corrosion is hindered 16–162 fold by IFKhAN-92 alone or 20–183 fold by its formulation with urotropine. We recommended the formulation of IFKhAN-92 with urotropine for protection of chromium-nickel steel in HCl solutions containing H2S. It efficiently hinders the metal corrosion (18–250 fold) up to 100°C and totally prevents hydrogen absorption up to 60°C, inclusively.

Keywords: acid corrosion, hydrogen sulfide, corrosion inhibitors, stainless steel, hydrogenation, triazoles

Int. J. Corros. Scale Inhib., 2016, 5, no. 1, 87–99 PDF (916 K)
doi: 10.17675/2305-6894-2016-5-1-7

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