In-operation evaluation for corrosion in bottom floor of oil storage tanks by acoustic emission method: application of acoustic emission method to field tanks and relationship between AE signal parameters and plate-thickness measurement data

摘要

This paper discusses some noise factors affecting the AE evaluation of external corrosion on bottom plate of real oil storage tanks, and also the relation of the AE parameters examined during in-operation to the current local corrosion state (statistical corrosion rate) estimated from thickness measurement data. The inner oil flows, oil or water drops from corn type roof and natural wind has been investigated as the typical and important sources of noise in in-operation real tank. In order to establish the diagnostics for degradation state due to corrosion on bottom plates, the measured AE signals have been compared with the parameters determined by the "risk curve for corrosion" derived from ultrasonic plate thickness measurement data as the current progress rate of corrosion in the much more corroded area. The result has shown the feasibility and applicability of the AE method for the in-operation evaluation of corrosion state in real oil storage tanks.