What Is Tank Floor MFL Inspection?
Tank floor Magnetic Flux Leakage (MFL) inspection uses a motorised floor scanner equipped
with powerful permanent magnets to saturate each floor plate section with magnetic flux. Where
the floor plate is locally thinned by corrosion — from beneath (external corrosion at soil contact)
or from above (internal product-side corrosion) — the flux leaks from the plate surface and is
detected by an array of Hall effect sensors. The resulting data is processed to produce a colour
coded corrosion map of the entire scanned area.
MFL is the most widely specified method for the rapid 100% screening of storage tank floors
during out-of-service inspections — delivering coverage rates that would be impossible to
achieve with UT point measurements alone within typical tank cleaning and inspection
windows.
MFL tank floor inspection detects:
- Bottom-side corrosion (external, soil-contact) — the primary corrosion concern in most
tanks
- Top-side corrosion (internal, product-contact)
- Generalised corrosion and localised pitting
- Perforation and through-wall holes
MFL limitations:
- Standard MFL is limited to floor plate thicknesses up to approximately 12–15mm
- Thick floor plates, thick coatings, or heavily corroded surfaces may require SLOFEC — see
the SLOFEC page
- MFL provides a relative indication of wall loss severity — confirmation
- UT is required for
accurate remaining wall measurement at flagged locations