The applicability of the acoustic emission (AE) technique for the location and occurrence of corrosion damages in metallic structures is well known; systematic tests have been conducted in laboratory and field. The AE method can be used to detect corrosion growth online for periodically active corrosion or offline for active corrosion during measurement. AE signals from a corrosion process are low-amplitude signals compared to other damaging emission mechanisms such as crack growth. AE corrosion signals can be of similar amplitudes as background noise.