The influence of flow rate on corrosion of mild steel in hot tap water

Flow rate influence on corrosion rate of mild steel St3 in tap water (total hardness and total alkalinity equal 4) at 50 °C was studied in a loop setup using LPR and weight loss techniques. The flow rate increase from 0.19 to 0.45 m/s reduces corrosion rate by 2.8 times within 150 h of testing; relative amounts of magnetite and calcite in the surface deposits decrease and increase, respectively, according to XRD. The division of the surface into cathodic and anodic zones is confirmed by SEM. A plausible explanation of the flow rate influence on corrosion rate reduction is suggested.