Tank Roofs

98% Inspection
Coverage

848K Readings on
117’ (35m) Diameter Roof

Several Corrosion
Areas Identified

Robot-Only
On Roof

Gecko’s continued expansion into the Oil and Gas sector, aided by its new office in Houston, TX, gave the opportunity to complete an NDT Inspection of an Above Ground Storage Tank (AST) Roof for a 60,000 barrel per day refinery in Oklahoma. The inspection utilized the TOKA 4 robot with Ultrasonic and Visual Inspection methods. Before Gecko, the refinery was experiencing unnecessary risk to inspectors and structural integrity of the tank due to increased weight and other common problems with manual inspection methods on their AST Roofs.

Manual inspection methods utilize gridding, typically one square foot, with one UT reading per grid to determine corrosion rates required under API Standard 653. While manual methods may meet specification requirements, the customer realized the inherent limitations of manual inspection reliability with one data point per square foot. Corrosive environments inside ASTs are rarely uniform, and therefore inspection data density, delivered by the Gecko Robotics Inspection Team (GRIT), proved vital for an accurate representation of the structural health of the AST roof. Most important to this customer was complete coverage of the tank roof, previously not possible because of the need to keep inspectors from setting foot on the tank roof.

Footage of Gecko’s patented software displaying inspection data from TOKA 4. An HD visual camera takes photo and video throughout the entirety of an inspection

GRIT, consisting of two Level II NDT Inspectors and one TOKA 4 robot, captured over 848,000 UT thickness readings across the 117’ (35m) diameter roof to identify corrosion of the tank roof in two days. Post-inspection reporting revealed multiple areas of significant and widespread corrosion across the tank roof. The breadth of the corrosion problem could not have been similarly identified with manual UT inspection methods because of the limited quantity and wide dispersion of the UT thickness measurements.

To couple with the data, an HD camera installed on the robot captured thousands of photos of the tank roof. These photos are geolocated and stitched together with the color-coded Bokeh map for cross checking high corrosion areas with a visual inspection.