Question

what is flux leakage

Answer 1

It is defined as magnetic flux which does not flow the particularly intended path in a magnetic circuit.

Answer 2

Magnetic flux leakage (TFI or Transverse Field Inspection technology) is a magnetic method of nondestructive testing that is used to detect corrosion and pitting in steel structures, most commonly pipelines and storage tanks. The basic principle is that a powerful magnet is used to magnetize the steel.