Patent ID: 8368395

Claim:
A magnetic inspection device for nondestructively detecting discontinuities in the form of loss in metallic cross section and localized discontinuities in elongated magnetically permeable objects, comprising: a magnet having two opposite magnetic poles and for inducing, in sections of a magnetically permeable object between the poles, a magnetic flux at the saturation level; a magnetic sensor assembly configured to substantially circumscribe the entire circumference of the object, the magnetic sensor assembly having a magnetic flux detector positioned between the poles for sensing perturbations in leakage flux at the exterior surface of the object and measuring changes in cross sectional area of the object, as the object and inspection device move relative to one another; and a flux shield located between the magnetic sensor assembly and each magnetic pole of the magnet for absorbing secondary flux between the poles and in the vicinity of the flux detector to aid the magnetic sensor assembly in sensing the perturbations of leakage flux.