Corrosion of steel in weakly acidic media at low H2S concentrations

• L.E. Tsygankova¹, A.A. Kostyakova¹, N. Alshikha¹ and V.I. Vigdorovich^2,3

¹ Derzhavin State University, ul. Internatsyonalnaya, 33, Tambov, 392000 Russian Federation
² Tambov State Technical University, ul. Sovetskaya, 106, Tambov, 392000, Russian Federation
³ All-Russian Scientific Research Institute of Use of Machinery and Oil Products, Novo-Rubezhnyi per., 28, Tambov, 392022 Russian Federation

Abstract: The influence of low concentrations of H2S (25–200 mg/L) on the corrosion rate of St3 steel in model stratum water was studied by gravimetric, electrochemical methods and the linear polarization resistance method from ten-day experiments. In a simulated solution with pH = 6, an increase in the concentration of H2S in the range 25–100 mg/L causes an increase in the protective effect of H2S. At 200 mg/L H2S, the corrosion rate rises, but remains lower than in the solution without H2S. Introduction of an organic inhibitor to solutions containing H2S in these concentrations enhances the protective effect. Electron microscopy was used to characterize the state of the metal surface after corrosion. In a simulated solution with a lower pH (3.6), only 25 mg/L of H2S causes a decrease in the corrosion rate of the steel.

Keywords: steel, hydrogen sulphide, protective effect, model stratum water, inhibitor, impedance, polarization

Int. J. Corros. Scale Inhib., 2018, 7, no. 1, 102-111 PDF (1 273 K)
doi: 10.17675/2305-6894-2018-7-1-9

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