TIME OF FLIGHT DIFFRACTION (TOFD) SERVICES
NATTS TIME OF FLIGHT DIFFRACTION SERVICES
Time of flight diffraction (TOFD) is among the most reliable nondestructive testing methods in testing welds for both pre-service and in-service inspection.
An accurate evaluation of welds is essential to make sure that defects don’t compromise the balance and integrity of welded structures.
This ultrasonic method can be used in a varied selection of industries including
- Oil & gas
- power generation and
Calculating the amplitude of the reflected signal is usually a relatively unreliable approach to sizing defects because the amplitude strongly depends upon the orientation of the crack.
Instead of amplitude, TOFD uses enough time of flight of an ultrasonic pulse to look for the placement and size of a reflector.
In a TOFD program, a pair of ultrasonic probes sits on opposite sides of a weld. Among the probes, the transmitter, emits an ultrasonic pulse that’s found by the probe, on the other hand, the receiver.
In undamaged pipes, the signals detected by the receiver probe are from two waves: One that travels along the surface and one that reflects off the far wall. When a crack is present, there is diffraction of the ultrasonic wave from the tips(s) of the crack.
Using the measured time of flight of the pulse, the depth of crack tips could be calculated automatically by basic trigonometry.