Since the development of eddy current testing in the early to mid-1900s this method has been used to detect defects and properties of many types of metals. The most common applications are testing tubular products for transverse defects, testing bar or wire products for longitudinal surface defects, and testing parts for defects and properties such as hardness.

One of the first requirements for the performance of nondestructive testing (NDT) arose when visual inspections were mandated following fatalities from a boiler explosion in the late 1800s. The need to formalize the qualification of NDT practitioners gradually became apparent.