Measurements of Surface-Breaking Flaws in Steel Pipes Using a SQUID Susceptometer in an Unshielded Environment

This paper describes the application of a SQUID susceptometer in nondestructive evaluation of steel pipes used in oil refineries. Commonly used methods, such as ultrasound and eddy current techniques [1], normally need a very small liftoff distance between the pipe wall and the sensor, which would require removal of the thermal insulation protecting the pipe, thus increasing the costs related to the inspection.