Acoustic Emission for Corrosion Detection

Corrosion is the major cause of structural degradation in industrial plant and structures; the consequences of not identifying its presence and status can be severe, leading to a myriad of methods for its evaluation and monitoring. Amongst these there are a large number based on acoustic methods, and this paper concentrates on three variations involving passive monitoring with the aim of summarizing their usual area of applications and limitations. Passive monitoring involves listening to the process of corrosion itself, which usually causes acoustic emission as a result of the fracture and de-bonding of expansive corrosion products, localised yielding, or micro-crack formation. This method is applied to reinforced concrete structures, storage tank floors, and process plant whilst in service.