Effect of Inhibition on the Pitting Stability and Growth Kinetics of 316 Stainless Steel in an Acetic Acid Storage Tank

A 316L stainless steel tank storing inhibited acetic acid perforated due to pitting corrosion after less than 3 years in service. This paper presents potentiodynamic polarization, potentiostatic and galvanostatic test results using reagent grade solutions compared to acid from the field. Organic chlorides used during the formulation of the corrosion inhibitor proved to be the primary cause of the pitting corrosion, which led to severe pitting damage at the weld heat-affected zones. Various preventive measures (coating, passivation paste, cathodic protection) were tested in the laboratory. The primary preventive measure applied was to remove the inhibitor for the acid blend.