Abstract: A pipeline inspection tool includes two pole magnets oriented at an oblique angle relative to the central longitudinal axis of the tool body. An array of sensor coil sets is located between opposing edges of the two pole magnets and oriented perpendicular to the central longitudinal axis. Each sensor coil set includes a transmitter coil and two opposing pairs of receiver coils that are gated to receive reflections from the wall of a tubular member. Because the line of sensor coils is rotated relative to the magnetic bias field, the receiver coils are in-line with, and have the same angular orientation as, the transmitter coil. The tool provides improved sensitivity to small defects, substantial decrease in RF pulser power requirements, full circumferential coverage, self-calibration of the transmitted signals, and less interference between transmitter coils caused by acoustic ring around.

Abstract: A pipeline inspection tool includes two pole magnets oriented at an oblique angle relative to the central longitudinal axis of the tool body. An array of sensor coil sets is located between opposing edges of the two pole magnets and oriented perpendicular to the central longitudinal axis. Each sensor coil set includes a transmitter coil and two opposing pairs of receiver coils that are gated to receive reflections from the wall of a tubular member. Because the line of sensor coils is rotated relative to the magnetic bias field, the receiver coils are in-line with, and have the same angular orientation as, the transmitter coil. The tool provides improved sensitivity to small defects, substantial decrease in RF pulser power requirements, full circumferential coverage, self-calibration of the transmitted signals, and less interference between transmitter coils caused by acoustic ring around.

Abstract: A guided wave electromagnetic acoustic transducer for detecting defects in moving metallic products such as rods, tubes and the like and which has coils energized by pulse of a few cycles of a high frequency alternating voltage which produces an alternating field in the product, the coils being alternately wound and connected in series and measuring dynamic acoustic stress that is a function of the radial distance from the center of the product being tested and produces a reading that is different than that showing a surface defect in the product.

Abstract: This invention relates to a Electromagnetic Acoustic Transducer which has the ability to detect flaws in assorted metallic objects, such as pipes, rods, bars and the like, including those objects which are already installed and cannot be removed without a major undertaking. The Transducer also has an embodiment which includes hinged arms for surrounding the circular objects that have already been installed such as piping. The system employs Lamb waves to move along the surface of metallic objects to affect a bounced return to thereby allow detection of flaws on the surface or in the interior of said objects.

Abstract: An improved high temperature electromagnetic acoustic transducer (EMAT) for conducting inspections of materials with elevated temperatures, which has cooling means using gas cooling, such as air or nitrogen, for cooling the transducer RF coil, the onboard circuitry and magnets, while also providing for the easy removal of the coil and onboard circuitry. Prior art EMAT's are susceptible to failure since high temperatures reduces the signal quality of the electronics components, degrades the insulation of the RF coils, and permanent magnets can loose field strength.

Abstract: An enhanced EMAT probe and coil construction takes advantage of heat transfer and magnetic flux principles to permit inspection of workpieces at elevated temperatures of 1200.degree. F. and higher. A ferromagnetic, cup-shaped probe assembly having an end cap and a barrel is provided for carrying a coil assembly, preferably one or more permanent magnets, and a frustoconical focus core. The magnets are located within the barrel and connected to the end cap, and the cup-shaped probe assembly positions the coil assembly proximate the surface of the workpiece. A plurality of passageways may be provided in the end cap and barrel for admitting cooling air to an interior portion of the cup-shaped probe assembly. The cup-shaped probe assembly serves to provide a return path for magnetic flux of the magnetic field back to the permanent magnet means.

Abstract: A preamplification and impedance matching circuit for an electromagnetic acoustic transducer includes an impedance matching section of the circuit having input terminals for receiving radio frequency power from a radio frequency power source. A matching transformer, which is a step-down transformer, is operatively connected to the input terminals. Diode networks are operatively connected to the matching transformer and output terminals which lead to the coil of the transducer. Signal responses emitted by the transducer coil are transmitted to a preamplifier section of the circuit. Choke coils or resistors are used to limit radio frequency power entry into the preamplifier section of the circuit.

Abstract: Defects such as corrosion located on the exterior of a component such as a metal pipe, tank, vessel or support structure which is insulated by a coating or cover, are detected by a low frequency eddy current (LOFEC) system. A magnetizing yoke in the shape of an inverted U is placed on the cover insulating a metal component. An excitation coil is wrapped around the magnetizing yoke for carrying an altering current in order to produce an alternating magnetic field by the magnetized yoke. The alternating magnetic field produced by the magnetized yoke induces an eddy current which runs through the metal component between the legs of the yoke. A pair of magnetic flux sensors are used in differential connection beneath one or more excitation coils which can be articulated to conform to varying pipe diameter. In addition, an absolute signal response can be obtained from one of the receiver coils.

Abstract: Defects such as corrosion located on either the inner diameter or outer diameter of a covered metal component are detected through eddy current inspection. At least two concentric magnetizing yokes are held fixed with respect to each other and are scanned over the cover of the component. A magnetic flux sensor on the leg of each yoke detects changes in the magnetic flux that penetrates at different depth regions in the covered metal component, depending on the relative postion of each magnetizing yoke.

Abstract: Defects such as corrosion located on a covered metal component are detected through Eddy current inspection using stationary magnetic fields and scanning sensors arrays. A magnetizing yoke is held fixed to the cover of the component and a magnetic flux sensor is used to scan the area between the legs of the yoke over the cover of the component. Also, a fixed array of sensors can be provided between the legs of the yoke for automatic multiplexing of the sensors and sampling in sequence of signal responses picked up by sensors in the sensor array. Additionally, a stationary magnetic field arrangement is provided by a plurality of probes aligned adjacent and parallel with each other. A fixed array of magnetic flux sensors are arranged between the legs of the aligned probes for scanning for defects. This arrangement of fixed sesnsors can be used for underwater use and sealed by a sealing compound.

Abstract: A remote tone burst pulser for an electromagnetic acoustic transducer utilizes a circuit having a direct current power source which is provided to a main capacitor. A high power, high speed insulated gate bipolar transistor or metal oxide-semiconductor controlled thyristor is operatively connected to the main capacitor and the coil of the transducer. A drive circuit is operatively connected to this device for transmitting a train of switch pulses which causes radio frequency alternating current to be provided to the transducer coil. A power transistor is operatively connected to the first transistor and is activated by a second drive circuit for causing a conducting state which allows for the power being applied to the transducer coil to be rapidly dissipated by a resistor and the internal resistance of the power transistor.

Abstract: An apparatus and method for discriminating between flaw depths of 5% and 10% of the tube wall thickness of electric resistance welds are disclosed. At least two electromagnetic acoustic transducers (EMATs) are employed to generate ultrasonic surface and shear waves. A logic circuit discriminating means selectively activates an alarm for flaw depths of about 10% or greater, but does not activate the alarm for flaw depths of about 5% or less, thereby avoiding waste in time and materials.

Abstract: A serpentine tube inspection positioning spine formed from a plurality of identical links mated together. Each link has first and second bifurcated ends with the first end sized to fit within the second end of an adjacent link. Links are mated together by a pivot pin or axle which is accepted in a bore through the bifurcated ends. The second bifurcated end is provided with a substantially oval-shaped bore to allow sliding of the adjacent links relative to each other. Flat alignment faces on each end, with the first end having rounded corners, prevent buckling due to compressive forces during insertion while still allowing pivoting of the links for traveling through tubing bends.

Abstract: A serpentine tube inspection positioning spine formed from a plurality of identical links mated together. Each link has first and second bifurcated ends with the first end sized to fit within the second end of an adjacent link. Links are mated together by a pivot pin or axle which is accepted in a bore through the bifurcated ends. The second bifurcated end is provided with a substantially oval-shaped bore to allow sliding of the adjacent links relative to each other. Flat alignment faces on each end, with the first end having rounded corners, prevent buckling due to compressive forces during insertion while still allowing pivoting of the links for traveling through tubing bends.

Abstract: A serpentine tube inspection positioning spine formed from a plurality of identical links mated together. Each link has first and second bifurcated ends with the first end sized to fit within the second end of an adjacent link. Links are mated together by a pivot pin or axle which is accepted in a bore through the bifurcated ends. The second bifurcated end is provided with a substantially oval-shaped bore to allow sliding of the adjacent links relative to each other. Flat alignment faces on each end, with the first end having rounded corners, prevent buckling due to compressive forces during insertion while still allowing pivoting of the links for traveling through tubing bends.

Abstract: A serpentine tube inspection positioning spine formed from a plurality of identical links mated together. Each link has first and second bifurcated ends with the first end sized to fit within the second end of an adjacent link. Links are mated together by a pivot pin or axle which is accepted in a bore through the bifurcated ends. The second bifurcated end is provided with a substantially oval-shaped bore to allow sliding of the adjacent links relative to each other. Flat alignment faces on each end, with the first end having rounded corners, prevent buckling due to compressive forces during insertion while still allowing pivoting of the links for traveling through tubing bends.

Abstract: An apparatus for scanning header tube holes includes a probe assembly designed to engage the surface of the header encircling a header tube hole. The probe assembly includes a spring mounted sensor, in a preferred arrangement, an eddy current probe. A mechanism is provided for supporting and positioning the probe assembly. The mechanism is adapted, in operation, with resilient rings engaging the tube stub. A drive device is provided for imparting axial and circumferential movement to the probe relative to the surface of the hole which is to be inspected.

Abstract: An ultrasonic testing method and apparatus stores the reflected ultrasonic signals from each of a plurality of locations along a scan path over a piece of material to be tested. For each individual location, the reflected signal at that location is added to contributing signals from each other location to produce a composite signal which has a good signal-to-noise ratio. The contributing signals from each other location is formed by multiplying the signal of those other locations by a corrective phase shift factor which is a characteristic of a time delay for a reflected signal from the other locations to the individual location of interest. The contributing signal from each other location thus represents a rotated reflected signal from the other locations.

Abstract: A moisture-measuring device for measuring moisture of the ambient on one side of a solid wall comprises a piezoelectric crystal sonically coupled to the wall on a surface thereof facing the one side. A capacitor or other moisture sensitive impedance means is connected to the piezoelectric crystal over a network which is operable to provide a response indicative of the impedance of the capacitor upon excitation of the crystal at the resonant frequency of the circuit. The capacitor comprises at least two spaced plates which are exposed to the ambient. Change in moisture in the ambient thus causes change in capacitance of the capacitor. By sonically exciting the piezoelectric crystal from an opposite side of the wall, a measure of change in resonant frequency of the network can be made. This measurement is related to the moisture content of the ambient.

Abstract: An apparatus for inspecting for cracks under installed fasteners and the like using a multiple frequency digital eddy current system. A computer with a plurality of digital arrays generate drive signals which are converted to analog and applied to the test coil, a second set of digital arrays generate balance signals, are adjusted in amplitude and phase and drive signals so that the output of the test coil is zero in a test specimen, output signals from a work piece are processed in the computer giving phase-sensitive crack detection.