Magnetic Flux Leakage Inspections (MFL)are a method of non-destructive testing (NDT) that can detect and assess pitting, corrosion and wall loss in both lined and unlined metallic storage tanks and pipelines. Powerful magnets are used to magnetize the steel, areas with corrosion or missing metal will “leak” the magnetic field from the steel. MFL inspections tools have sensors placed between the poles of the magnet to pinpoint leaks in the magnetic field.
How Does it Work?
When inspecting the floor of a tank, the floor of the tank is “swept” with the MFL inspections tool. The area is coated with magnetic flux, then rare earth magnets are used to temporarily magnetize the steel, while the magnetic field is changing, our equipment records and analyzes the changes. If the magnetic field is uniform, that indicates that there are no flaws in the tank floor. If however, the magnetic field is distorted, there are internal and/or external flaws present, like pitting or corrosion. This distortion or “leakage” can be measured by the sensors.
Our technicians mark areas that need to be verified by visual and ultrasonic inspections. The results of MFL inspections can be used to establish an existing baseline for the equipment or to determine remaining wall thickness and fit-for-service corrosion calculations in accordance with API, EEMUA and other standards.