การทดสอบโดยเทคนิค Time of Flight Diffraction (TOFD) Time of Flight Diffraction (TOFD)

Time of Flight Diffraction is conducted by place a pair of ultrasonic probes on opposite sides of a weld. One of the probes, the transmitter, emits an ultrasonic pulse that is picked up by another probe, the receiver. In undamaged pipes, the signals picked up by the receiver probe consist two waves: one that travels along the surface and one that reflects off the far wall. When a crack is present, there is a diffraction of the ultrasonic wave from the tip(s) of the crack. Using the measured time of flight of the pulse, the depth of a crack tips can be calculated automatically
by simple trigonometry. With the simplicity of the technique and skills of Qualitech’s staff, we can ensure testing speed and accuracy to the customers.

Application:
Time of Flight Diffraction is generally accepted as being particularly sensitive to 'tight' vertically orientated planar defects such as cracks and LOF. Because it is fast, efficient, ease of visibility and records all raw data for presentation in a proportionate and representative fashion, TOFD is an ideal detection tool which provides an accurate and invaluable 'fingerprint' of condition as a quality control function at the time of construction.

Benefit:
- Precise sizing capability makes it an ideal flaw monitoring method
- Quick to set up and conduct inspection
- Fast scanning with imaging of full data recording
- Can used for corrosion inspections
- Highly sensitive to all weld flaw types
- Can be used in high temperature environment