Abstract: Method and apparatus for performing eddy current flaw inspection on workpiece material such as steel bar stock. A drive mechanism propels a workpiece longitudinally along a workpiece path. An array of electromagnetic transmitter coils is disposed about the workpiece path. An electromagnetic source energizes the transmitter coils under control of multiplexing circuitry. The multiplexing circuitry and source actuate respective transmitter coils in a predetermined iterative sequence. The sequential actuation induces eddy currents in the workpiece at a succession of locations extending iteratively about the workpiece circumference. Circuitry coupled to multiple, differentially wound sensing coils detects variations in eddy current produced in the workpiece and utilizes these detected variations to produce flaw indicating signals.

Abstract: Eddy current test apparatus of the type that generates eddy currents in an object and that senses flaws or defects by sensing changes in the induced eddy current. Two differential encircling coils surround a moving workpiece moving relative to said coils. One of the two test coils has an enclosed tubular pathway forming a loop adjacent to the coil. A steel ball is placed in the enclosed tubular pathway and is air driven through the pathway so that it continuously revolves in close proximity to the coil. The steel ball disrupts the magnetic field flux generated by the test coil in the workpiece. This disruption modifies the eddy current in the workpiece which in turn induces a well defined output signal in the test coil. In an alternate and preferred embodiment, two ferrite object are rotated near the two encircling coils to disrupt the eddy currents produced by both coils. The ferrite objects are radially offset so that they do not disrupt the magnetic field near a flaw at the same time.

Abstract: Method and apparatus for scanning a generally cylindrical workpiece for flaws. A cylindrical metallic sleeve is rotatably supported about a workpiece path of travel. Two differentially wound energization coils surround the sleeve near two apertures in the sleeve. The coils are energized with a high frequency signal that induces eddy currents in the workpiece. The apertures periodically disrupt the eddy current inducing magnetic fields and enhances signals from the coils indicative of the presence of flaws in the workpiece.

Abstract: An ultrasonic flaw detector for detecting irregularities in an object, such as a pipe, having a segment of annular cross-section. The detector includes a transducer with an involute transmitting surface for sending ultrasonic signals into the object at equal non-radial angles of incidence. The detector further includes transmission apparatus for maintaining a constant physical relationship between the transducer and the pipe and interpretive apparatus for correlating reflections of ultrasonic signals within the object with irregularities.

Abstract: An ultrasonic flaw detector for detecting irregularities in an object, such as a pipe, having a segment of annular cross-section. The detector includes a transducer with an involute transmitting surface for sending ultrasonic signals into the object at equal non-radial angles of incidence. The detector further includes transmission apparatus for maintaining a constant physical relationship between the transducer and the pipe and interpretive apparatus for correlating reflections of ultrasonic signals within the object with irregularities.