The ultrasonic testing as an NDT method provides indications of surface and subsurface discontinuities, with the potential to determine the depth and exact size by the use of beams of mechanical waves (vibrations) of short wavelength and high frequency, transmitted from a small probe in contact with the specimen surface and detected by the same or other probes. These Ultrasonic pulses could indicate the presence, absence, and location of flaws, interface and/or discontinuities.

Ultrasonic examination for thickness determination may be made using either the resonance or pulse-echo technique. This technique determines thickness or reveals corrosion discontinuities near the surface or deep within components or structures. Applications include location of manufacturing defects in welds and castings through to Corrosion / Erosion monitoring and large scale corrosion mapping.