Mcdermott Technology, Inc.

The Babcock & Wilcox Company

Other

Jimmy W Hancock

Daniel T MacLauchlan

Wayne M Latham

George H Harth, Iii

Donald M Stevens

Charles B Overby

Carlton E Stinnett

Michael J Kelly

Ralph D Murphy

Jayne Marie Grut

An EMAT device for non-destructive inspection of the surface of a tube for cracks using acoustic surface waves includes a pulsed magnet having an active surface for facing the surface of a tube to be inspected. A receive emat coil is on the active surface and a transmit emat coil is on the opposite surface of the receive coil. The transmit emat coil has a scan surface for scanning over the tube surface. A transmitter for generating and transmitting an RF signal to the transmit emat coil is provided for generating a transmitted acoustic wave signal along the tube, the transmitted wave creating a reflected acoustic wave if a crack in the tube is encountered, the reflected wave generating a reflection signal in the receive emat coil. A receiver is connected to the receive emat coil for receiving the reflection signal. A digital computer is connected to the receiver for receiving and for processing the reflection signal and a display displays information about a crack in the tube which created the reflected acoustic wave and resulting reflection signal.

Electromagnetic acoustic transducer (EMAT) inspection of cracks in boiler tubes

An EMAT arrangement utilizes separate transmitter and receiver EMATs which may each be connected to a tuning capacitor by a stripline cable. An electrostatic shield may also be provided between the coils and the coils can be offset from each other by &frac12; the pitch distance of sections in the coil. This reduces the duration of main bang, thus making it possible for the EMAT arrangement to detect structures which are very close to the coils.

Main bang recovery EMAT

An EMAT testing device for nondestructively testing tubes for surface defects and displaying the results has a EMAT transmitter arranged collinear with a pair of EMAT receivers. The EMAT receivers each receive a pair of oppositely propagating circumferential acoustic surface waves from the transmitter at different times and the relative amplitudes of the received waves are compared to located defects adjacent the receivers in the tube.

Electromagnetic acoustic transducer (EMAT) inspection of tubes for

An EMAT arrangement utilizes separate transmitter and receiver EMATs which may each be connected to a tuning capacitor by a stripline cable. An electrostatic shield may also be provided between the coils and the coils can be offset from each other by 1/2 the pitch distance of sections in the coil. This reduces the duration of main bang, thus making it possible for the EMAT arrangement to detect structures which are very close to the coils.

A method of electromagnetically measuring the distance between adjacent tube elements in a heat exchanger. A cylindrical, high magnetic permeability ferrite slug is placed in the tube adjacent the spacing to be measured. A bobbin or annular coil type probe operated in the absolute mode is inserted into a second tube adjacent the spacing to be measured. From prior calibrations on the response of the eddy current coil, the signals from the coil, when sensing the presence of the ferrite slug, are used to determine the spacing between the tubes.

Eddy current measurement of tube element spacing

A variable power source is provided having multiple power modules each of which can produce a portion of the total range of voltage required for pulsed operation of an electromagnetic acoustic transducer electromagnet. The power modules are connected in series, and controlled by individual potentiometers which are simultaneously adjusted. Selector switches are provided for enabling or disabling each module. The output of the power modules is connected to a pulser/controller for wave forming prior to sending the output signal to the electromagnet. A noise filter can be placed between the power modules and the pulser. LED-type indicators on the selector switches may be used to indicate the operational status of the modules.

Portable electromagnetic acoustic transducer pulser controller

An ultrasonic inspection method for measuring the thickness of non-welded (non-metallurgically bonded) cladding on the inside surface of a vessel from an outside diameter surface of the vessel relies upon the occurrence of a phase change at an interface between the base metal and cladding layers to precisely determine its presence and location. By measuring the length of time for the ultrasonic pulse to propagate through the cladding material, suitable predetermined calibration standards for the cladding material in question can be used to convert the time of flight of the ultrasonic pulses through the cladding into a thickness of the cladding. The cladding thickness can be measured from an outside surface of the vessel whether or not it is empty and/or without stopping the process and/or draining it, and the method can even be employed at elevated temperatures through the use of known delay lines. Alternatively, if safe access to the interior portion of the vessel is available, an internal direct inspection can be performed to determine the thickness of the non-welded cladding using a modification of the technique in which a first multiple or second reflection signal from the base metal/cladding layer interface is used.

Ultrasonic technique for measuring the thickness of cladding on the

An apparatus and method for scanning the outer profile of control rods in a control rod assembly includes a plurality of rotatably mounted ultrasonic transducers which are mounted for rotation about the axis of at least some of the control rods in the assembly. The assembly is moved in a linear path parallel to the axis of the control rods, past the rotating transducers for scanning the surfaces of the control rods in helical paths. By distributing the transducers in a selected configuration, all control rods in the assembly can eventually be scanned.

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Lynchburg, VA, United States of America

Jimmy W Hancock