Flow-Assisted Corrosion of Carbon Steel Under Neutral Water Conditions

Flow-assisted corrosion (FAC) often has caused serious damage to carbon steel piping in nuclear power plants. As a first stage of experiments to determine the effects of water chemistry parameters on FAC, corrosion rates of carbon steel were measured in 140°C pure water with an online corrosion rate monitor based on electrical resistance measurement as [O2] and flow velocity were changed. The data were compiled as a function of electrochemical corrosion potential (ECP) and flow velocity. It was concluded that the FAC rate was below the detectable limit in highly oxygenated conditions, where [O2] was >50 ppb and ECP was above –0.2 VSHE; and the effects of preoxidation treatment disappeared rapidly under deaerated conditions.