Phased Array Ultrasonic Testing
(PAUT), also known as Phased Array UT, is an advanced non-destructive inspection technique that uses a set of Ultrasonic Testing (UT) probes made up of numerous small elements. Phased array systems pulse and receive from multiple elements of an array. These elements are pulsed in such a way as to cause multiple beam components to combine with each other and form a single wave front traveling in the desired direction. Similarly, the receiver function combines the input from multiple elements into a single presentation. Because phasing technology permits electronic beam shaping and steering, it is possible to generate a vast number of different ultrasonic beam profiles from a single probe assembly, and this beam steering can be dynamically programmed to create electronic scans:
Time Of Flight Diffraction (TOFD)
Time of Flight Diffraction (TOFD) method of Ultrasonic Testing is a sensitive and accurate method of Non Destructive Testing method for detecting welds defects. TOFD is a fast and efficient way to scan a lot of weld area in a very short time period. Dead zones near the front and back surface can be enhanced using combined TOFD and Conventional Pulse Echo Techniques. Measuring the amplitude of reflected signal is a relatively unreliable method of sizing defects because the amplitude strongly depends on the orientation of the defect. Instead of amplitude, TOFD uses the time of flight of an ultrasonic pulse to determine the position and size of a reflector. In theory TOFD relies on the information gathered from the diffracted ultrasonic signals impinging on the tips of the defects especially cracks. It is an excellent tools to capture the correct location of a crack especially transverse cracks. With the combination of TOFD and Phased Array a complete weld scan for transverse and horizontal defects can be made easy.
