This instrument is developed for measuring corrosion under the bottom of the large storage tank floor often found in the Oil and Gas industries. The corrosion damage leads to undesirable leaks that have significant environmental implications. The system uses a unique approach to the use of ultrasonic guided waves that are generated outside the tank and interrogate the inner regions. The robotic system is capable of achieving inspection speeds of 1 m per minute that allows for a 100 m diameter tank to be inspected in one shift.  This system is currently evaluated by several refineries including Exxon Mobil, and Shell in Singapore.