Abstract: Both a system and method are provided for mapping the magnitude of residual compressive stresses over the surface of a ferromagnetic machine component, such as a valve ring of the type used in refrigeration compressors. The system includes an eddy current probe having a detection coil for emanating a fluctuating electromagnetic field that shallowly penetrates the surface of the valve ring or other ferromagnetic component, a probe circuit connected to the coil for both conducting a high frequency alternating electric current through the coil and detecting changes in the impedance in the coil, and a scanning mechanism having a turntable for supporting and rotating the component. A support arm positions the coil of the eddy current over a central portion of the valve ring while the ring is rotated by the turntable and changes in coil impedance are detected by the probe circuit.

Abstract: System for inspecting the interior of tube plugs, particularly tube plugs of the type having expander elements disposed therein. The system includes a probe assembly connectable to the tube plug, the probe assembly having a rotatable and translatable probe carrier housing for housing a sensor probe capable of inspecting the tube plug. The probe assembly also includes a leaf spring extending through the probe carrier housing and attached to the sensor probe for radially outwardly biasing the sensor probe into sensing contact with the interior of the tube plug, particularly the interior of the tube plug located between the top of the tube plug and the expander element. A tangle-free flexible hose is connected at one end thereof to the probe carrier housing for transversely rotating and longitudinally translating the probe carrier housing. The flexible hose is also connected at the other end thereof to a probe driver assembly that rotates the flexible hose which in turn rotates the probe carrier housing.

Abstract: An apparatus for inspecting an item having grooves machined therein includes a main housing having longitudinal grooves formed in opposite sides thereof. The main housing defines an underside for contacting the item to be inspected. A carriage has opposite sides adapted for slidably engaging the longitudinal grooves in the main housing. A sensor is provided for inspecting the item. A mechanism is provided for connecting the sensor to the carriage such that the sensor extends beyond the underside of the main housing. The mechanism is adjustable so that the degree of extension of the sensor beyond the underside of the main housing may be controlled. A reference member is adjustably connected to, and extends from, the underside of the main housing for enabling the main housing to smoothly follow each groove.

Abstract: An apparatus and a method for remotely inspecting the interior walls of a cavity having a circular cross section that varies in diameter, such as the interior of a hollow tube plug. The apparatus has an eddy current probe head having a distal and proximal end, wherein the distal end engages the cavity walls, an elongated support assembly connected to the proximal end of the probe that is insertable within the cavity, a radial extender mechanism for radially extending and withdrawing the distal end of the probe with respect to the longitudinal axis of the support assembly, and a probe driving and delivery system for inserting the support assembly into the cavity and helically moving the probe head to inspect the cavity walls for discontinuities.

Abstract: An improved fluid mandrel having an eddy current probe connected thereto is disclosed herein. The eddy current probe generally comprises a probe body which is detachably connectable to the bottom of a fluid mandrel on one end, and a source of hydraulic fluid on the other end. The probe body includes a pair of sensing coils which are separated along the longitudinal axis of the body by a distance approximately equal to the thickness of the metallic structure desired to be detected. The improved mandrel finds particular application in performing expansions which eliminate the clearance between heat exchange tubes extending through the baffle plates in nuclear steam generators. In such an application, the sensing coils of the probe are longitudinally spaced the same distance as the thickness of the baffle plates in order to generate a sharp and unambiguous electronic signal indicative of the relative positions of the mandrel and the baffle plate.

Abstract: An apparatus for simulating and analyzing discontinuities in a tube using eddy current inspection techniques is disclosed. The simulation apparatus includes inner and outer tubular members arranged to define an annular chamber having a predetermined tubular configuration corresponding to the tubular configuration of a tube under investigation. The outer tubular member has an opening through the wall thereof and the inner tubular member defines an axially extending hollow interior. A supply of electrically conductive liquid material is provided in the annular chamber, the quantity of liquid material being such as to substantially and completely fill the annular chamber in the vicinity of the opening through the wall of the outer tubular member. A defect simulation member is supported in the opening in the outer tubular member for movement along a predetermined direction extending transverse to the axis of the inner tubular member.