Effect of pre-exposure of sulfur and iron sulfide on H2S corrosion at different temperatures

Abstract

The study has been carried out to investigate the effect of elemental sulfur and iron sulfide on corrosion behavior of carbon steel in sour environment. It was found that both compounds could form a protective layer of corrosion products even at low pH and high temperature levels. In general, bare steel electrode behaved as sacrificial anode in two metal galvanic coupling with sulfur or iron sulfide covered steel electrode. However, some examples of opposite behavior were observed in the tests with iron sulfide. The surface of bare steel electrode was coated with a thin black layer and had no evidence of changes due to corrosion. In other hand, surface of sulfur-covered electrode had well adherent thick dark film with traces of pitting. In the case with iron sulfide-covered electrode, the metal surface remained bright with crevice corrosion region.