XYZ Chemicals is the main producer of ammonium nitrate (NH4NO3) in Asia. Their chemical plant uses mild steel tank to keep the ammonium nitrate before distributions. The tank has a wall thickness of 5cm and due to corrosion; the maintenance team has to ensure that the thickness should not be less than 3cm to avoid catastrophic accident. a) Assuming a corrosion penetration rate of 6000mdd and the corrosion on the inside surface is uniform, how long will it take before the tank has to be changed? The density of steel is 7.9g/cm3. (5 marks) b) Since chemical production is a continuous process and it would be very costly to request a shut down for regular maintenance tasks, how do you suggest the maintenance team to monitor the corrosion occurrence of the tank in operation? (7 marks) c) If the tank is used to keep aerated recycled water instead of ammonium nitrate, what are your comments with regards to the corrosion risk and behaviour