Low Frequency Electromagnetic Technique
This Technique was developed to Inspect flat bottom storage tank floor. Over time, scanners have been contoured to inspect convex or concave ferrous metal piping surface. Various scanner are available for most application.
Brief about Technique:
A low frequency electromagnetic field is injected into the plate using an external horseshoe shaped driver coil placed in such a manner that the return magnetic field is through the area to be tested as shown in figure – 1. A flaw distorts the magnetic flux lines, which is sensed by sensors. The extent of defect is measured by observing the change in phase and/or amplitude. The flaws detected by LFET during the scanning can be further verified using ultrasonic testing.
