Corrosion monitoring of sulfuric acid tank under anodic protection by electrochemical noise

In this research, the tanks made of carbon steel, similar to the practical conditions and in the form of pilot, was investigated. The tank containing 98% and 72% sulfuric acid was evaluated by potentiodynamic polarization test, open circuit potentials and potentiostatic test. Also, electrochemical noise measurement was carried out before, during and after the anodic protection, and the results were analyzed by statistical analysis at time intervals. . By analyzing the frequency range, PSD curves were obtained and it was observed that the values of slope and current and potential skewness could be used to determine the deviation or non-deviation of the normal distribution of electrochemical noise data. It was also found that by using spectral density curves, it is possible to eliminate the negative effects of additional noise and obtain complete information about the corrosion process. Noise resistance was obtained, but the noise resistance could be applied qualitatively to determine the corrosion rate. In this study, it was concluded that the electrochemical noise method is an efficient method for studying corrosion phenomena, such as crevice corrosion and anodic protection system during protection of tanks and heat exchangers in sulfuric acid. It was found that for a mild steel tank in Sulfuric Acid 98%, during protection, the slope value of the ROLL-OFF region was 2.4 and for dilute sulfuric acid 4.4, and it was found that in this area, the anodic protection was considerably high for carbon steel so protection in the sulfuric acid solution 72% is more suitable.