Ultrasonic testing is another form of non-destructive testing where a transducer applies ultrasonic pulse waves in the frequency range of 0.5 to 10MHz in the material and the time of flight of the ultrasonic waves is measured from the initiation time to the return of the reflection to the transducer.

Any change in acoustic impedance produces ultrasonic reflection or echo, this property of the ultrasound is used to identify the material wall thickness and any internal discontinuities in material.

Ultrasonic testing is very sensitive test method for detection of embedded linear discontinuities. Ultrasonic testing is faster and economical as compared to radiographic examination.

The common applications of ultrasonic testing are

• Wall thickness measurement (UTT),
• Corrosion mapping, lamination testing (ULT)
• Flaw (discontinuities) detection in the material e.g. welds, castings, forgings and other wrought products (UFD)