Acoustic emission study of active–passive transitions during carbon steel erosion–corrosion in concentrated sulfuric acid

Abstract In concentrated sulfuric acid plants, erosion–corrosion failures of carbon steel pipes are common. Under a critical flow velocity, a ferrous sulfate layer (FeSO 4 ) protects the metal against corrosion. Above this velocity, the layer becomes instable and active corrosion may conduct to rapid metal wastage. Numerous factors can act upon this critical velocity. Thus, it is really interesting to define an industrial tool allowing the determination of “active–passive” transitions for this phenomenon. For that purpose, acoustic emission has been chosen. Acoustic sensors were coupled with carbon steel portions of an erosion loop. Through the evolution of acoustic activity, different severity criteria have been evidenced.