The importance of welding in structures across all sectors of industry can't be overstated. Determining the quality of welds is often vital to the longevity and profitability of structures. Time-of-Flight Diffraction (TOFD) is an advanced NDT inspection method which is widely used for weld testing. Although not exclusively used for welds, it is very effective in detecting defects such as cracks, lack of fusion and slag inclusion.
ToFD is an innovation of ultrasonic testing which uses two probes. One probe sends the ultrasound and the other one is used as a receiver. Instead of recording the ultrasound that is reflected by defects, it detects diffraction of sound waves that emanate from the tips of a defect. ToFD inspection provides accurate information about the length and height of defects. Unlike other testing methods, ToFD can detect flaws regardless of their orientation.
ToFD is most widely applied for weld testing. However, it can also be used for inspection of forgings, pipes,, vessels, and steel constructions.