Original scientific paper
Possibilities of Reliable Ultrasonic Detection of Subwavelength Pipework Cracks
Ivan Hrabar
; INETEC–Institute for Nuclear Technology Ltd. Dolenica 28, Lučko, Croatia
Antonio Petošić
; University of Zagreb, Faculty of Electrical Engineering and Computing, Department of Electroacoustics Unska 3, 10000 Zagreb, Croatia
Petar Franček
; University of Zagreb, Faculty of Electrical Engineering and Computing, Department of Electroacoustics Unska 3, 10000 Zagreb, Croatia
Marko Budimir
; INETEC–Institute for Nuclear Technology Ltd. Dolenica 28, Lučko, Croatia
Abstract
An occurrence of cracks in pipework could lead to potentially very dangerous malfunction
in some critical engineering systems such as power plants. There is a clear trend of replacing
traditional manual testing with non-invasive in-situ methods that should detect crack formation in
its early stage. Such as approach would enable replacing of unhealthy pipe components during the
regular periodic outages. Ultrasonic testing is known to be a rather mature and reliable technology.
However, it suffers from serious problems in detection of the cracks of subwavelength size. This
paper attempts to soften aforementioned problems by investigating the influence of a duration of the
unipolar excitation signal on the achieved resolution. In addition, the transducer input electricalimpedance
of NDT transmitter was measured by using different excitation pulses and their levels
and the results are compared with those obtained using traditional frequency sweeping method at
low excitation levels. Finally, use of some advanced signal processing algorithms that might lead to
the automatic detection of subwavelength voids, in scenarios with low signal-to-noise ratio, is
discussed
Keywords
ultrasonic testing; NDT, subwavelength; transducer self-impedance
Hrčak ID:
237310
URI
Publication date:
28.10.2019.
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