Topographical profiles and mechanical property of corrosion product films on a pipeline steel in Desulfovibrio vulgaris -containing thin electrolyte layer characterised by atomic force microscopy

Abstract

Internal corrosion of wet gas pipelines usually occurs in thin layers of water condensate with dissolved gases such as CO₂, where a bacterial community can grow to cause microbiological corrosion. In this work, surface films generated during corrosion of an X52 pipeline steel under a CO₂-containing thin electrolyte layer (TEL) in the absence and presence of Desulfovibrio vulgaris bacteria were characterised by atomic force microscopy. The film generated in the Desulfovibrio vulgaris-containing TEL, i.e. a mixture of FeS, FeCO₃ and biopolymers, as compared with the film generated in the sterile TEL (i.e. FeCO₃-dominant corrosion products), is topographically less compact and softer, with a reduced elastic modulus. After 7 days of immersion, the elastic modulus of the surface films generated in the sterile and D. vulgaris-containing TELs are 11.81 and 6.79 GPa, respectively.