The initiation and development of mesa corrosion attack during CO2 corrosion of carbon steel has been studied in flow loop experiments performed at 80 °C and pH 5.8. Video recordings of growing mesa attacks have been performed in a test section with a glass window in the corrosion loop. These observations have shown that the mesa attack can grow both laterally and in depth below a lid of original corrosion film before the film is tom away stepwise by the flow. Possible mechanisms for initiation of mesa corrosion attack are discussed based on the observations from the video recordings. Mesa attacks can result from several small local attacks growing together into one large mesa attack.
Keywords: CO2 corrosion, mesa attack, carbon steel, sweet corrosion, video microscope