SIMULATION OF IRON CORROSION IN AERATED ACID SOLUTIONS

A theoretical study was carried out to analyze the corrosion of iron pipe and iron rotating cylinder in aerated hydrochloric acid using mixed potential theory equations under turbulent flow of Reynolds number of 5000, 10000,20000, 40000, and 60000, temperature of 25 °C, 40 °C, and 60 °C, and pH 1,2, and 4. The theoretical investigation included: the effect of Reynolds number, temperature, pH, relative roughness (e/d), and heat flux on corrosion rate and corrosion potential. The relation between the corrosion rate and corrosion potential in case of pipe flow and rotating cylinder was analyzed and discussed.Polarization diagrams were constructed using theoretical equations that wereproposed to describe the activation and concentration polarization of anodic and cathodic reaction for the whole investigated range of Reynolds number,temperature and pH.The theoretical results showed that corrosion rate and corrosion potential increase with increasing velocity and temperature and decrease with increasing pH for both pipe flow and rotating cylinder. The corrosion rate of iron pipe increases with increasing relative roughness and the corrosion potential shifted to more positive as the relative roughness increases and with increasing velocity, temperature, and pH.The corrosion rate and corrosion potential of iron smooth pipe increases with increasing the heat flux because of its effect on the wall temperature which in turn  affect the fluid physical properties especially the diffusivity and solubility of oxygen.