Condition Monitoring for Tank Floors of Above-Ground Storage Tanks

Advanced NDT Techniques (proceedings of MATEST 99 international conference), CrSNDT, 23&24 September 1999, CAVCAT/CROATIA , pp.127-131
Dr. Athanassios Anastassopoulos, Dimitrios Kouroussis


Tank floors are the most vulnerable parts of atmospheric storage tanks. Predictive maintenance requires corrosion assessment at regular intervals, so that repairs can take place, in order to prevent leaking resulting in severe implications to the environment and large amounts of lost product. Periodic tank floor inspections,  which require emptying of the tank regardless of its condition, lead to significant losses of money and time because of the unnecessary opening and emptying of tanks in good condition. The Acoustic Emission (AE) NDT technique offers solutions to the aforementioned problems. With the use of AE, the tank floor condition can be assessed without the need to empty the tank. The tank is monitored for 1-3 hours by an array of AE sensors placed on the outside part of the tank wall which detect signals arising from corrosion and/or leak. The result of this monitoring and post-processing of AE signals is a tank floor grading, from A (no damage) to E (major repair required) as well as graphs pinpointing the location of corrosion on the tank floor. Thus, the unnecessary opening of tanks in good condition is avoided, whereas high maintenance priority is given to tanks with severe damage, resulting in considerable savings. The present paper briefly outlines the AE method as applied in tank floor inspection and the TANKPAC technology (developed through thousands of tank bottom tests) by which tank floors are graded based on the AE activity.