Abstract
The function of corrosion inhibitors was investigated in controlling corrosion and related hydrogen entry into steel products in sour environments. Newly developed inhibitors, as well as commercially available ones, were examined through immersion tests of steels in NACE solution (NaCl 5% + CH3COOH 0.5%, saturated with H2S) containing an inhibitor. Highly effective inhibitors were found among organic nitrogen compounds with molecular weight more than 200. The study of the relation between molecular structure and inhibitive efficiency revealed that the substituted imidazolines with nine carbon atoms in the hydrophobic chain and with two aminoethylenes in the hydrophilic chain are the most efficient inhibitors. These imidazolines keep their excellent inhibitive properties even with one tenth of the critical concentration of a typical inhibitor being utilized in oil and gas fields over the temperature 25 to 60 C.
