Sour Water Tank Shell
For industrial facilities, engaging 3rd party contractors for asset inspections typically requires extended lead time and increased risk borne from large on-site teams. When Gecko partnered with an international refining company to complete an inspection on an eight-year-old sour water tank, our 2-person crew was onsite in under 24 hours after receiving communication and completed a rapid ultrasonic gridding (RUG) inspection on a sour water tank shell gathering 293K UT thickness measurements in one 12-hour shift.
Why 24 Hours?
The quick turnaround capability was essential due to a pyrophoric ignition incident that caused unknown damage to the tank being inspected. When facility staff weighed their inspection options, the leading method, at the time, was AUT because it provided a more complete understanding of tank health than manual UT methods. However, after connecting with the Gecko team, facility staff realized that Gecko’s robotic inspection method could capture the same amount of tank coverage in 25x - 50x the speed of AUT. This meant vastly more coverage of the tank in the remaining time that the facility had before a decision would need to be made regarding whether to take the tank offline.
The 2-person NDT Level II Gecko Robotics Inspection Team (GRIT) worked around the storage tank stiffener bands with eight robot drops around the circumference of the tank. This proved valuable, as each 45-degree section of the tank wall had numerous areas of internal corrosion near the fill line, which measured over 66% thinner than the same circumferential position merely 10 feet lower in elevation. Specifically identifying the fill line corrosion point, by providing a 360 degree view of the tank wall’s structural integrity allowed proper maintenance initiatives, taken in the necessary order, to minimize future risk of tank wall failure and subsequent ignition incidents with a cost effective solution.
Data rich deliverables, including RUG visuals and a Bokeh Plot, gave the refinery the ability to shift away from a reliance on minimal ultrasonic readings and educated guesses for maintenance initiatives. Once the maintenance was completed, the tank was permitted to operate for the next two years to complete the standard 10-year tank lifecycle. The customer was so impressed with Gecko’s inspection performance on the sour water tank that in the following nine months, Gecko was hired to inspect four additional assets at the same facility, including two additional tanks and piping subjected to highly corrosive environments.