Galvanic corrosion study of carbon steel to arsenic and antimony couples

Carbon steel has been observed to experience accelerated corrosion in pH adjusted geothermal brines. The damage mechanisms observed in service have included: heavy metal deposition, localised under-film corrosion, galvanic corrosion and erosion corrosion. This paper describes progress in the study of the corrosion properties of galvanic couples of carbon steel to antimony and to arsenic using electrochemical techniques in simulated brine at temperatures up to 80 °C. The results show galvanic corrosion rates of carbon steel increased as temperature was increased. Aeration gave enhanced galvanic corrosion of carbon steel coupled to antimony, a reverse effect was observed with arsenic. The differing performance of arsenic was attributed to one of arsine production under cathodic polarisation and/or rapid oxidation of the arsenic electrodes used in this work.