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|NDT.net Issue - 2017-06 - NEWS |
Short Range Guided Wave (SRUT) inspection is widely used for the detection of the pitting and scattered corrosion damages in the hard-to-access / no-access areas of the material such as annular rings inside the storage tanks, pipe walls above supports and under insulation, air to soil interface of the steel poles, etc.
Use of the phased array (PA) modality for such kind of inspection became possible thanks to the extremely powerful fully parallel and freely controlled PA pulser receiver of Sonotron NDT’s portable instruments ISONIC 3510, ISONIC 2010, ISONIC 2009 UPA Scope and a number of probes providing the efficient generation of the guided wave in the plates and tube walls. The linear and newly designed matrix array probes allow optimizing of the guided wave excitation in the material. In addition the matrix array probes allow coverage of the certain the area from a single probe position thanks to the ability of 3D control of the ultrasonic beam. Depending on the degree of scattered corrosion and the type of coating (painting) the damages may be detected at the distances from few centimeters to several meters. Comparing to the conventional modality the PA implementation of SRUT inspection provides the highest degree of signal optimization for the wider range of the material thickness with the limited nomenclature of probes thanks to the electronic control of the mode of excitation and receiving of guided waves. The video below illustrates capturing of the CB-Scan image of the cutoff sample taken out of the annular ring; the sample contains the real corrosion damages and artificial defects.
Switching to the multi-skip true-to-geometry coverage and imaging provides the ability of distinguishing between ID and OD surface defects and internal defects. The quantitative evaluation of the material loss is provided as well. This is made through the line-scanning along the area of interest and capturing the corresponding C-Scan. Upon C-Scan captured the statistical distribution of the material loss is provided at the postprocessing stage through marking the damage area on the C-Scan followed by the automatic analysis function – the process is illustrated by the video below.
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