Time of Flight Diffraction (TOFD)

Time of flight diffraction (TOFD) is an ultrasonic method for the detection, sizing and monitoring of flaws in new construction and in-service welds and components.

TOFD employs two longitudinal wave (L-wave) angle beam transducers arranged diametrically on opposite sides straddling the weld or base material under examination. One transducer acts as a transmitter of ultrasonic energy, while the other receives the returning signals. The transducer, pulse, and amplifier characteristics are selected to generate a broad distribution of energy allowing for full weld coverage with single scans. An electronic encoder records the position of the probe along the weld during the scan which enables a real-time display and recording of the digital images.