TWI Frequently asked questions
- Internal defects can be detected and sized
- Thick specimens take no more time to examine than thin ones
- Access to only one side of the component is needed
- There is no radiation hazard in ultrasonic examination, and hence no disruption of work as there is with radiography
- Planar defects can be detected, irrespective of their orientation
Disadvantages of ultrasonic inspection as a method of Non-Destructive Examination are:
- A high degree of operator skill and integrity is needed. Hence, the need for trained and certified NDT personnel
- In most examinations, there is no permanent record of the inspection as there is in radiography
- In certain materials, like austenitic steel, the large grain size found in welds can cause attenuation and this may mask defects
- Spurious indications, and the misreading of signals, can result in unnecessary repairs
