Back in 1988, inspecting storage tank floors was a laborious and error-prone process, involving manually sampling spot ultrasonic thickness measurements in a sparse grid-like pattern. A common approach was to record five-point measurements per plate, which resulted in less than one percent inspection coverage! But then came Saunderson's revolutionary solution: Magnetic Flux Leakage (MFL)1. Since then, MFL has come a long way and is now a widely recognized and established inspection method known for its ability to provide rapid, efficient, and comprehensive coverage of large ferrous structures such as the floors of Aboveground Storage Tanks (ASTs).

Tank floor inspections are critical to ensuring the safety and integrity of storage tanks, especially in the critical zone, defined by API Standard 653 as the portion of the tank bottom or annular plate within 76.2 millimeters (3 inches) of the inside edge of the shell, measured radially inward. In the past, inspecting the critical zone involved time consuming, fallible processes relying heavily on inspectors' integrity and Non-Destructive Testing (NDT) equipment limitations. Reporting on features detected in dead zones was a wholly manual process, and the actual coverage in these areas was impossible to record. Often, a secondary MFL tool was deployed in this area, without mapping capabilities. Over the previous decades, the industry has lived with a significant mismatch between actual inspection coverage and reported inspection coverage. However, with advancements in magnetic flux leakage scanners, and Eddyfi Technologies' Floormap®X, the process has become more reliable, efficient, and intuitive.

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