Abstract: An ultrasonic transducer is disclosed. The transducer includes a wear cap and an active element. The wear cap includes at least one slot arranged so as to define a strip. The strip is arranged to be in vibrational communication with the active element. The ultrasonic transducer may include a rigid block. The active element may be interposed between the wear cap and the rigid block, and the rigid block may be configured to provide a backing mass for the active element. Optionally, the rigid block may include chamfered edges.

Abstract: A method of determining a thickness of a region of wall- or plate-like structure which is thinner than a thickness of a surrounding region of the structure due to a cavity in the structure is disclosed. The method comprises comparing a measured time-frequency dispersion map for at least one dispersive guided wave obtained by measuring the structure using guided waves with a reference time-frequency dispersion map obtained by modelling the structure, determining a cut-off frequency, fc, at which the measured time-frequency dispersion map and the reference time-frequency dispersion map differ and calculating the thickness of the thinner region in dependence upon the cut-off frequency.

Abstract: A method of determining a thickness of a region of wall- or plate-like structure which is thinner than a thickness of a surrounding region of the structure due to a cavity in the structure is disclosed. The method comprises comparing a measured time-frequency dispersion map for at least one dispersive guided wave obtained by measuring the structure using guided waves with a reference time-frequency dispersion map obtained by modelling the structure, determining a cut-off frequency, fc, at which the measured time-frequency dispersion map and the reference time-frequency dispersion map differ and calculating the thickness of the thinner region in dependence upon the cut-off frequency.

Abstract: Processing signals acquired during guided wave testing A method of processing signals acquired during guided wave testing of an elongate member (2), such as a pipe, in which at least one guided wave (7) is generated in the elongate member, the at least one guided wave is reflected by reflectors (8) in the elongate member and reflected guided waves (9) are detected. The method comprises determining at least one reflection coefficient or a parameter for calibrating a guide wave test in dependence upon reflections from the reflectors which include at least one multiple reflection. The reflections may include a single reflection from a first reflector, a single reflection from a second reflector and a multiple reflection from the first and second reflectors.

Abstract: An ultrasonic transducer includes a wear plate (2), a piezoelectric element (8) arranged rearwards of the wear plate and a rigid block (16) arranged rearwards of the piezoelectric element and configured to provide a backing mass for the piezoelectric element. The wear plate extends across the piezoelectric element and rearwards so as to provide a cap over the piezoelectric element and sides of at least a forward portion of the rigid block.

Abstract: Processing signals acquired during guided wave testing A method of processing signals acquired during guided wave testing of an elongate member (2), such as a pipe, in which at least one guided wave (7) is generated in the elongate member, the at least one guided wave is reflected by reflectors (8) in the elongate member and reflected guided waves (9) are detected. The method comprises determining at least one reflection coefficient or a parameter for calibrating a guide wave test in dependence upon reflections from the reflectors which include at least one multiple reflection. The reflections may include a single reflection from a first reflector, a single reflection from a second reflector and a multiple reflection from the first and second reflectors.

Abstract: An apparatus for inspecting a pipe comprising a body adapted for passage through the bore of a pipe to be inspected, a main transducer array comprising a plurality of circumferentially spaced transducers for transmitting ultrasound energy, the transducers being mounted on the body for movement between a retracted position, wherein the body can freely move through the bore of the pipe, and an extended position wherein the plurality of transducers are pressed into operative contact with the inner wall of the pipe. An actuator selectively urges the plurality of transducers to their extended positions. A control transmits ultrasound energy into the pipe to propagate a guided wave within the pipe walls in at least one longitudinal direction along the pipe when the transducers are in their operative position and receives the propagated wave and analyzes the wave to determine the presence or absence of defects in the pipe wall.