Preparatory Notes for ASNT NDT Level III Examination - Ultrasonic Testing, UT

The disadvantages of ultrasonic inspection include the following:
• Manual operation requires careful attention by experienced technicians.
• Extensive technical knowledge is required for the development of
inspection procedures.
• Parts that are rough, irregular in shape, very small or thin, or not
homogeneous are difficult to inspect.
• Discontinuities that are present in a shallow layer immediately beneath the
surface may not be detectable.
• Couplants are needed to provide effective transfer of ultrasonic wave
energy between transducers and parts being inspected.
• Reference standards are needed, both for calibrating the equipment and
for characterizing flaws.