Lorem 

Eddy current inspection uses the principal of “electromagnetism” as the basis for conducting examinations. Eddy currents are induced through a process called electromagnetic induction. When alternating current is applied to a probe a magnetic field develops in and around the conductor. If another electrical conductor is brought into the close proximity to this changing magnetic field, current will be induced in this second conductor. Discontinuities within the second conductor interact with the flow of eddy current and modify the induced magnetic field. The changes in the magnetic field are reflected as the impedance variation of probe.  The electrical impedance of the test probe is modified by the tube dimensions, electrical conductivity, magnetic permeability and metallurgical or mechanical discontinuities in the tube. Each discontinuity produces a unique electromagnetic response.  

In the proper circumstances, eddy currents can be used for crack/defect detection, material thickness, coating thickness and conductivity measurements. Some of the advantages of eddy current inspection include good sensitive to small cracks and other defects, capable of detecting surface detects and near surface defects, no contact required with the part to be tested. Some of the limitations of eddy current inspection include applicable to conductive materials only, requirement of extensive skill and training.  Flaws such as delaminations that lie parallel to the probe coil winding and probe scan direction may be undetectable.

Eddy current examination is a rapid method for determining the conditions of tubes in a bundle. Both general wall thickness and local defects (for example pitting) can be detected and quantified. Also detectable is whether a defect is located on the interior or exterior of the tube. By applying a multi-frequency techniques defects under support brackets may be detected.