Eddy current instruments are nondestructive testing (NDT) devices that induce detectable eddy currents in conductive materials. They are used to detect flaws, determine thickness, inspect welds, measure conductivity, and sort alloys. Eddy current instruments include a straight or angled magnetic probe and an analog or digital meter with a zero reference point. Moving the magnetic probe over the surface of a conductive material such as a metal tube induces circulating currents (eddies) of electrons that oppose the externally applied magnetic field from the probe. Surface irregularities such as cracks and corrosion interrupt the surface flow of eddy currents and are detected. Eddy current instruments are well-suited for NDT because they can determine material or part characteristics without permanently altering the test subject. They vary widely in terms of capabilities, but are suitable for a variety of application and industries.

