Detection of localized corrosion in ferromagnetic metal pipe under insulation with pulsed eddy current testing

Probe design was studied by simulation and experiments to improve detection sensitivity of localized corrosion in ferromagnetic metal pipe under insulation with pulsed eddy current (PEC) non-destructive testing. A reversely-connected dual coil was used as excitation source to produce a focused and intense magnetic field without the need of large current in the coil. Finite element method was used to simulate and compare the distribution of magnetic field and eddy current of single coil excitation and dual coil excitation, and a series of experiments were then performed. The experimental results agreed well with the simulation and showed that a much higher sensitivity was achieved using reversely-connected dual coil as excitation than using single coil excitation in the localized corrosion detection of ferromagnetic metal pipe under insulation with PEC testing. This research provides reference for probe design in the localized corrosion detection in metal pipe under insulation with PEC method.