Corrosion of UNS S30400 and S31600 stainless steel in a geothermoelectric plant in Cerro Prieto, Mexico has been studied. The stainless steel ducts for conduction of geothermal vapour suffer from microbiologically induced corrosion (MIC) at elevated temperatures.

Experimental procedures include microbiological, biochemical, electrochemical, optical and electronic microscopy techniques. The plant conditions affecting corrosion phenomena were simulated by laboratory tests. Corrosion events were located and identified and their mechanisms are described and discussed. The conclusions contribute to understand the corrosion process and its remedy to minimise and avoid corrosion in the plant operation.