Classification of Corrosion-AEs Form Noises for Corrosion Inspection of Oil Storage Tank Floor Plate
Hideo CHO, Akio YONEZU, Hiroaki SUZUKI and Mikio TAKEMOTO
Abstract:Classification of corrosion-AEs from noises is attempted for the source location of acoustic emissions (AEs) from storage tank in service. As the AEs are monitored by resonant-type sensors with center frequencies lower than 50 kHz and amplified by 60dB, the system detects both the corrosion-AEs and noises. Noises are generally minimized by changing the threshold value of the monitoring system or interrupting the monitoring during strong winds and rain drops, but not be separated based on the quantitative waveform analyses. We first studied waveform characteristics of AE events monitored by sensors mounted on annular plate or side wall of the tank, and then separated corrosion-AEs from noises. Percentage of corrosion-AEs to the total events are found to be 30`50 % of the total events monitored by the sensors on the annular plate in windless day, but less than 10 % at the monitoring on windy day. Key Words:Acoustic emission, Signal, Noise, Storage tank, Floor plate, Corrosion