Eddy Current Testing

Eddy current inspection is one of several NDT methods that use the principal of "electromagnetism" as the basis for conducting examinations. Several other methods such as Remote Field Testing (RFT), Near Field Testing (NFT) and Flux Leakage.

Eddy currents are created through a process called electromagnetic induction. When alternating current is applied to the conductor, such as copper wire, a magnetic field develops in and around the conductor. This magnetic field expands as the alternating current rises to maximum and collapses as the current is reduced to zero. If another electrical conductor is brought into the close proximity to this changing magnetic field, current will be induced in this second conductor. Eddy currents are induced electrical currents that flow in a circular path. They get their name from "eddies" that are formed when a liquid or gas flows in a circular path around obstacles when conditions are right.

Eddy current testing is a reliable method for inspecting heat exchanger tubing for corrosion, cracking and fatigue. This method allows rapid inspection of the tube and can provide accurate results of the tube condition.

This instrument screen printout shows the results of 304 stainless steel tubing in a vertical heat exchanger. Most of the tubes in this heat exchanger had severe OD corrosion towards the top of the tubes.

Eddy current testing can be applied to many applications including aircraft, welding, tubes and complex shapes. Contact us today about the specifics of your project.