The MFE tank-floor scanner-a case history

The large storage tanks that are familiar features of oil terminals, refineries, chemical and petrochemical installations have problems with leaks caused by corrosion of their mild-steel floor plates. During scheduled routine inspections, it is highly desirable to find any active corrosion that could lead to failure before the next routine inspection. A DC magnetic flux leakage technique, referred to as magnetic flux exclusion (MFE) which was selected for such, the inspection is described. This application of MFE involves locally magnetising the floor plate with a trolley-mounted magnet and looking for anomalies in the field immediately above the floor surface caused by local loss of metal. No special surface preparation is required