Inspection technique for above ground storage tank floors using MsS technology

Above ground storage tanks are required to undergo periodic internal inspections. Because these inspections are hazardous and expensive to conduct from the inside of the tank, there is a keen interest for alternative inspection techniques that can be conducted without removing the tanks from service. Southwest Research Institute® (SwRI®) is currently developing a screening technique that uses magnetostrictive sensor (MsS) guided wave technology and a Synthetic Aperture Focusing Technique (SAFT) to map the condition of a tank floor from the outside of the tank. Preliminary testing was conducted on a mockup constructed to resemble the outer annulus of the tank floor and the attached tank wall. A test procedure was developed where the MsS probe was scanned around the outside circumference of the tank to collect a Bscan array of waveforms. Testing has demonstrated that the inspection technique is effective at detecting both pitting corrosion and broad local corrosion in the outer annulus of the tank floor.