NDT knowledge – Ultrasonic

Ultrasonic test is an inspection method that uses high frequency sound energy to conduct examinations and make measurements.

Ultrasonic test can be used for flaw detection/evaluation, dimensional measurements, material characterization, and much more applications.

Ultrasonic testing is often performed on steel and other metals and alloys, though it can also be used on concrete, wood and composites, albeit with less resolution.

It is used in many industries including steel and aluminium construction, metallurgy, manufacturing, aerospace, automotive and other transportation sectors.

A typical UT inspection system consists of several functional units, such as the pulser/receiver, transducer, and display devices.

A pulser/receiver is an electronic device that can produce high voltage electrical pulses. Driven by the pulser, the transducer generates high frequency ultrasonic energy.


The sound energy is introduced and propagates through the materials in the form of waves.

When there is a discontinuity (such as a crack) in the wave path, part of the energy will be reflected back from the flaw surface.

The reflected wave signal is transformed into an electrical signal by the transducer and is displayed on a screen.

Advantages & limitations 

Some of the advantages of Ultrasonic inspection include:

  • Sensitive to both surface & sub-surface discontinuities.
  • Depth of penetration is superior to other NDT methods.
  • Only single side access is needed when the pulse-echo technique is used.

Some of the limitations of Ultrasonic inspection include:

  • Linear defects oriented parallel to the sound beam may go undetected.
  • Inspector skills and training required is more extensive than other techniques.
  • Materials that are rough, irregular in shape, very small, exceptionally thin or not homogeneous are difficult to inspect.

The Ultrasonic course will consist of 8 days for Training (theory & Practicum) + 2 days for exams. The course outline and syllabus is . . .