Magnaflux Corporation

John J Flaherty

Eric J Strauts

Donald E Lorenzi

Donald T O'Connor

Edward Schaefer

Timothy C Loose

Helmut F Wagerer

Peter J Rosauer

An indicating system is disclosed for use with nondestructive testing systems of various types including an eddy current instrument in which the characteristics of a specimen structure are indicated by the form, position and dimensions of a trace on a screen. The system indicates whether or not the relationship of two test signals is within certain limits which can be shown in the form of outlines or a series of contiguous boxes on a screen. Prior to the testing of a structure of unknown characteristics, such limits may be learned or recorded by the system either during the manual manipulation of a joystick control or the like or during the testing of a structure of known or standard characteristics.

Indicating system for use in nondestructive testing

Pipeline inspection apparatus is provided including a camera unit and associated illumination means, preferably a strobe flash unit, for recording on photographic film the rectangular images corresponding to generally rectangular internal surface portions of a pipe for detection of defects, a viewing axis of the camera being normal to the axis of the pipe. Weight means are provided for operating in a manner such as to establish a viewing axis in predetermined angular relation to a vertical plane through the axis of a horizontal pipe. In one embodiment, the device is supported by resilient cups for movement through the pipe and the entire device is rotatable under the influence of the weight means. In another embodiment, at least the optical portion of the camera unit is rotatably supported and connected to the weight means. Magnetic flaw detection means are provided for triggering the camera unit.

Pipeline inspection apparatus

An eddy current type of nondestructive testing instrument is disclosed in which the operating frequency is automatically adjusted in accordance with a comparison of output signals obtained in scanning operations in which the frequency is adjusted over its range. The system may be used, for example, in providing lift-off compensation for conductivity measurements or flaw detection or it may be used for sorting of parts of different characteristics.

Nondestructive testing system having automatic set-up means

Pipeline inspection apparatus is provided including a camera unit and associated illumination means, preferably a strobe flash unit, for recording on photographic film the images of internal surface portions of a pipe for detection of defects. The camera unit is moved longitudinally within a pipeline by a drive unit which preferably includes electric motors energized from a self-contained battery unit. Important features relate to means for automatically reversing the drive of the apparatus after it has travelled a predetermined distance and to mechanical features for facilitating movement of the device through bends and the like.

An ultrasonic system for detection of defects is provided including a pulse-echo instrument having a cathode ray tube on which an A-scan visual indication of flaws is produced and including a doppler circuit arranged to produce a doppler signal in an audible range in response to movement of a transducer relative to defects in a pipe seam or other region being investigated. The doppler signal is applied to earphones, permitting the existence of defects to be reliably determined audibly, after which the defects may be more carefully studied through the visual indications on the cathode ray tube. The doppler signal is also recorded on one track of a magnetic tape with operator's comments being recorded on a second track of the same tape. The doppler circuit includes an oscillator operated during a gating time interval to generate a reference signal, a phase detector responsive to a reference signal and to echo ignals, and a sample and hold circuit for storing the output of the phase detector from one cycle to the next.

Ultrasonic testing system

A method and apparatus for calibrating a gamma ray inspection system for measuring the wall thickness of a tubular product such as a pipe or the like, the system including a gamma ray beam generating station, means for conveying a tubular product axially past the gamma ray beam, the gamma ray generator being rotated during the axial movement of the tubular product, means for detecting the amount of attenuation of the gamma rays passing through the tubular product, and a calibration block having a first portion with a thickness corresponding to twice the nominal wall thickness of the tubular product to be inspected, and a second portion having a thickness corresponding to a predetermined amount less than the nominal wall thickness. Means are provided for selectively introducing the first portion and the second portion of the calibration block into the gamma ray beam to enable the operator to calibrate the equipment and to be able to detect tubular products which are defective in terms of thickness.

Gamma ray calibration system

A storage system is provided in which digital numbers are read into a memory by periodically sampling a pair of analog input signals and in which the memory is scanned in timed relation to the signal sampling and also in timed relation to the scanning of a cathode ray tube screen in a raster pattern, the scanning spot being brightened when a stored digital number is detected. A pair of digital-to-analog converters are used both in sampling and for raster scanning. In sampling, the outputs thereof are compared with the input signals to control analog-to-digital logic circuits and the inputs thereof are connected through multiplexers to the output of the analog-to-digital logic circuits which operate as successive approximation registers. In raster scanning, the inputs of the digital-to-analog converters are connected to counter sections driven from a high frequency clock one being operative to develop a sawtooth signal to generate a sweep line and the other being operative at a field or frame rate. The memory is also connected through the multiplexers, alternately to the outputs of the analog-to-digital logic circuits and to the counters to be scanned in synchronism with the scanning of the screen. The multiplexers are so switched that sampling is performed between successive sweep lines.

Flying spot pattern storage system

Conductivity measuring instruments are provided in which a test coil is supplied with alternating current and a detector responds to the voltage across the test coil to develop an analog voltage which is applied to a linearization circuit to develop an output voltage as a linear function of conductivity, the output voltage being applied to a digital read-out unit. As a function of conductivity, the analog voltage is single-valued, preferably with no more than a gradual slope change over a wide range of conductivity values. In one embodiment, a high impedance is provided in series with the test coil, the detector is a phase detector operated to respond primarily to the inductive component and linearization circuit is of a diode-function type. Alternatives are in the use of a phase-to-voltage type of detector and in the use of a digital type of detector and in the use of a digital type of linearization circuit.

Conductivity measuring instrument having linearization means and a

Automatic balancing circuits are provided for non-destructive testing systems such as eddy current systems in which an unbalance of a probe circuit including a test coil produces undesired deviations from a null indication. Error signal components are generated from a probe circuit output signal, stored in storage means and then applied in a balancing direction to cancel the effect of the unbalance of the probe circuit. Preferably, the error signal components are generated by a pair of quadrature phase detectors and the storage means comprises either a capacitor or the combination of digital storage and digital-analog converter means. The balancing is performed either automatically, with a delay in the storage operation, or by operation of a switch means between a sample or null condition in which the error signals are stored and a hold condition in which the stored error signals are applied. In one embodiment, the stored error signals are used to modulate AC signal components in quadrature phase relation which are applied in a balancing direction. In another, the stored error signals are developed from phase detector output signals and then combined therewith. In both embodiments, balancing signals are combined with signals derived from the probe circuit output signal and applied at points preceding high gain amplification in signal processing circuitry.

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Elk Grove Village, IL, United States of America

John J Flaherty