Time of Flight Diffraction
Why PAUT?
PAUT provides sharper detection capability for off-angle cracks and is capable of displaying multiple presentations simultaneously. It applies computer-controlled excitation to individual elements in a multi element probed. By varying the timing of the excitation, the sound beam can swept through a range of angle. The shape of the beam may also be modified to a specific focal distance or spot.
Advantages Over Radiography:
- No safety barrication is required in conventional method thus eliminating all radiation protection measures.
- No health and safety hazards while using highly ionizing radiations
- Higher reliability of examination than radiography
- Provides 100% coverage of welds with high scanning speed and reducing time
- Able to characterize and size a number of defects with two dimensional sizing
- Possible to deliver both hard and soft copies of results
Limitations:
- Skilled operators are not easily available as the technique is new
- Tube wall thickness should be >4.5 mm for the detection and characterization of defects
Conclusion:
PAUT/TOFD provides advantages in saving time and money along with reducing health and safety implications. In addition to this, it can detect all types of defects and characterize them in accordance with the acceptance criteria.
