Robotics can be used as a nondestructive method to find corrosion under insulation (CUI), as explained by Chase David (Gecko Robotics) in Tuesday’s AMPPiTheater presentation at the 2023 AMPP Annual Conference + Expo. CUI occurs when moisture is trapped behind insulation, corroding the metal underneath.

While traditional methods such as visual inspection (where the insulation is physically removed to look at the metal underneath), pulsed eddy current, radiography, and guided wave UT can be time intensive or unable to characterize localized corrosion, techniques such as automated ultrasonic testing (AUT), rapid AUT, and rapid ultrasonic gridding (RUG) offer a more efficient solution.

According to David, these methods use a tethered robot inside of a pipe or tank that can cover anywhere from 130 to 5,000 feet per day, taking hundreds of readings per second. Two-dimensional (2-D) and three-dimensional (3-D) c-scan corrosion maps are produced, and the onboard camera can take high-definition imagery.

RUG provides the most coverage at 5,000 square feet, with a tradeoff of decreased resolution. However, it can be followed by AUT focused on the areas that have been flagged for a second look. The rapid AUT, which travels 500 to 1,000 square feet over a 12-hour shift, has a high enough resolution that a second scan is not needed.

As David explained, the best part of using robotic solutions to find CUI is that it can turn a 30-day project into as little as one or two days, which can save time and money.