Study On Pitting Corrosion Of Storage Tank Bottom Steel In Acidic Condition Using Acoustic Emission

The pitting corrosion of atmospheric storage tank (AST) bottom steel specimens was studied by combined using acoustic emission (AE) and electrochemical polarization techniques in acidic NaCl solution. The AE signal characteristic parameters including amplitude, energy, hits, duration time and rise time varied over time, and the relationship between them were analyzed in each stage of pitting corrosion process. The AE parameters and electrochemical polarization curve in time domain were also compared. The result shows that the AE activity is consistent with that of potentiodynamic polarization. The AE signal features are remarkably different in oxidized film rupture, pits propagation and corrosion products movement of the pitting stage. Extracting these AE signal features will be of great help for diagnosing the corrosion severity and identifying the corrosion type of the AE on-line storage tank bottom inspection, and further to assess the corrosion degree of the whole storage tank bottom.