TOFD & PHASED ARRAY TECHNIQUE
Our TOFD and Phased Array system, used to examine welded joints, with a full record of the whole inspection. Comparing with the conventional ultrasonic testing TOFD and PA are much more sensitive and allow for a more exact dimensioning of the indications. TOFD is usually backed up with conventional probes or with Phased Array probes.
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TOFD EXAMINATION (TIME OF FLIGHT DIFFRACTION)
TOFD (Time of Flight Diffraction) ultrasonic technique is one of the most sensitive and most accurate techniques for non-destructive examination of welded joints. Using TOFD allows for a very precise dimensioning of any cracks. Unlike other ultrasonic techniques TOFD does not use ultrasonic signal amplitude and so it is not susceptible to an inconvenient orientation of the defect. Instead ultrasonic signal amplitude TOFD uses signals from diffraction waves to ascertain the localization of the indications.
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PHASED ARRAY EXAMINATION
A PA probe comprises of many small ultrasonic transducers lined up in a row, from which each can be manipulated independently. Changing for example the time needed to awaken the transducers, so that the ultrasonic waves were sent out one by one, we can determine the angle of the resultant ultrasonic beam. In other words, the ultrasonic beam can be manipulated electronically. The beam scans the examined object (a weld, a forging) much like the torch beam lightens a room. Many such ultrasonic beams are composed into a complete image which allows "slicing" the examined object.
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TEST SCANNER
A very important element of the test equipment is the scanner. Its objective is to simultaneously run several probes, both on flat surfaces and during testing of circumferential and longitudinal welded joints of pipes. Our scanner allows work on pipes with a diameter up to 1,5".
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HOW DOES TOFD WORK?
TOFD technique uses a couple of probes positioned on the opposite sides of the weld. One of the probes emits an ultrasonic signal which is then picked up by the second probe. If there are no defects in the weld, two waves are received: one travels just beneath the surface whilst the other is deflected from the opposite surface (the bottom). Simultaneously with the defect appears the ultrasonic wave diffraction, which is detected by the receiving probe. Research shows that TOFD is more reliable then x-ray examination.
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THE TRAITS OF OUR TEST SYSTEM
- A very clear picture simplifying the interpretation and assessment of the construction condition with the possibility of "slicing" the examined object into slivers
- The ability to program the test by changing the positioning of the probes, scanning techniques or focusing
- A higher complexity level of PA and TOFD techniques comparing to classical ultrasonic techniques
