Shear Wave UT – Crack Sizing

The ability to determine the depth of a crack through the thickness of a vessel shell is a very important attribute of shear wave UT. However, the accuracy of the depth measurements made with UT can vary considerably, depending on the technique used and the skill of the technician.

UT crack sizing techniques are classified as either “amplitude based” or “time based.” Amplitude based techniques were the first to be developed, and are still the most frequently used. They are relatively simple to use, but it has been learned that they do not always give accurate results. Time based techniques have been more recently developed and are capable of providing significantly more accurate depth measurement. However, they are more difficult to use than amplitude based techniques, and, therefore, appreciably more skill and expertise is necessary to obtain accurate results.

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