Ultrasonic testing

Ultrasonic testing (UT) and ultrasonic wall thickness testing (UTWT)

Unlike previous inspection techniques, ultrasonic testing (UT) is a volumetric, non-destructive testing method. This method makes it possible to detect defects on the inside of material.

An ultrasonic transducer is used to transmit high-frequency sound waves through the material. Based on the thickness of the material we calculate the time when this pulse is recaptured by the ultrasonic transducer.

With discontinuities in the material the pulse will return more quickly. This is how we determine the depth, size, nature and orientation of what has been detected. This technique is also used to determine wall thicknesses of all kinds of objects such as storage tanks, pipes, plates, etc.

At which stage do we use Ultrasonic testing (UT)? 

Applications of ultrasonic testing (UT):

  • forged parts
  • plating
  • castings
  • welded parts
  • corrosion checks

The advantages and disadvantages of Ultrasonic Testing (UT):


  • immediate availability of accurate representative test results
  • an understanding the size, orientation, shape and nature of defects
  • high penetration capacity
  • high level of sensitivity
  • only one surface needs to be accessible
  • excellent inspection method for the detection of surface fractures and internal defects


  • surface accessibility is required to be able to transmit ultrasound
  • a medium (gel or oil) is required to allow undisturbed guidance of the transmission of the ultrasound
  • objects with a rough surface or very small, thin or non-homogeneous objects are more difficult to inspect
  • cast iron and other materials with a coarse structure are difficult to inspect due to low sound transmission and high signal noise
  • linear indications parallel to the direction of the sound pulse usually remain unnoticed
  • reference standards are needed for equipment calibration and for assessing indications

In which industry do we use Ultrasonic testing (UT)? 

Industries in which ultrasonic testing is used:

  • construction steel and machine building
  • civil engineering and infrastructure works
  • oil, gas and wind industry, onshore and offshore
  • the shipping industry, shipbuilding and ship repairs