On-Line Monitoring Using Electrochemical Noise Measurement in CO-CO2-H2O Systems

The stress corrosion cracking (SCC) susceptibility of carbon steel extends over a narrow range of potentials in environments that contain a mixture of wet carbon monoxide-carbon dioxide (CO-CO2) gas. Normal fluctuations in plant operation may cause movement in and out of this range of potentials. Stress corrosion cracking in this case is discontinuous, and an opportunity exists to prevent it by process control. Electrochemical noise measurement, because of its capability for operation in thin film condensate conditions, is an attractive technique for monitoring corrosion in wet CO-CO2 systems. Laboratory tests and plant trials were carried out to determine if electrochemical noise measurement could be used to characterize periods of SCC.