Remote-field eddy current testing: a review

The remote-field eddy current technique is reviewed from its origins in the 1950s through its commercial utilization in the 1960s for the in situ inspection of oil well casings to research currently being conducted to expand its applications. The advantages and disadvantages of the method are outlined and evaluated. The development of theoretical modeling techniques, both analytical and numerical, is discussed. Graphs depicting electromagnetic field measurements on well casings and a block diagram of the casing inspection tool are included along with a casing remote field representation. Applications such as the nondestructive evaluation of carbon steel tubing in power steam generators, small diameter heat exchangers, and gas distribution pipes are mentioned.