A review of SQUID magnetometry applied to nondestructive evaluation

The development of the SQUID as the most sensitive instrument known for the measurement of changes in magnetic flux has presented new opportunities for its use for nondestructive evaluation (NDE) of electrically conducting and ferromagnetic structures. The preliminary studies of this application within the past few years are reviewed in order to serve as an introduction to those that follow. It includes early work by the author that explored the ability of a SQUID to detect defects in a buried pipe and to detect fatigue in steel structures. Studies designed to find defects in North Sea oil platforms and corrosion currents are covered, as well as more recent work in mapping the magnetic field above a current-carrying circuit board. The future of SQUID-based NDE is discussed.