What is a limitation of tap-testing NDT?

The proper understanding of tap-testing non-destructive testing (NDT) methods highlights that one of the main limitations is indeed the inability to provide depth estimates regarding defects. Tap-testing primarily focuses on evaluating surface conditions through sound generated by tapping the material and interpreting the resulting acoustic responses. While this method can reveal surface and some shallow defects, it does not have the capability to accurately measure the depth of any flaws that may reside deeper within the material.

The assessment relies on the assumption that changes in sound will indicate the presence of a defect, but the nature of the technique does not lend itself to quantifying how deep these defects are. This limitation is significant in applications where understanding the depth of a defect is critical for evaluating the integrity and safety of a component.