Evaluation of the efficiency of corrosion inhibitors for pipe steels in hydrogen-sulfide-containing media

Abstract

About one third of newly explored gas fields in the Ukraine contain at most 1 vol.% of hydrogen sulfide. For gas fields with relatively low contents of hydrogen sulfide, the application of materials with elevated resistance to hydrogen-sulfide stress-corrosion cracking (HSSC) and hydrogen-induced cracking leads to unreasonably high costs spent for the equipment of gas fields. At the same time, the application of insufficiently resistant materials may lead to failures of the equipment with unpredictable consequences [1–3]. Thus, it is most reasonable to use steels with relatively low resistance to HSSC in combination with inhibitors. For the protection against hydrogen-sulfide corrosion, it is proposed to use various domestic and foreign inhibitors [4–6]. They decrease the rate of general corrosion but not always serve as reliable protectors of steel against stress-corrosion cracking. Until recently, the gas-processing equipment of the Lokachyn Gas Field has been protected against possible corrosion failures by the Naftokhim-3 corrosion inhibitor produced by the “Galychyna” Enterprise (Drohobych) or by the DODICOR inhibitor (Germany) with similar properties [7]. At that time, the Naftokhim-8 inhibitor was not commercially produced. Its testing was originated in June 2005, parallel with testing of the Naftokhim-3 and DODICOR inhibitors. In view of these facts, the development of highly efficient commercially available domestic inhibitors and the analysis of their protective action under the conditions close to operating is a quite urgent problem.