TOFD - TIME OF FLIGHT DIFRACTION

TOFD is an ultrasound method primarily used for testing of welded joints. Its main advantages are, in particular, high speed of the inspection itself and assessment of the severity of possible defects on the basis of their real dimensions (length and height). The method is extremely sensitive to planar imperfections, such as for instance lack of fusion and crack, whereas it is relatively insensitive to the imperfection orientation.

TOFD method can also be successfully used to measure corrosion or erosion losses at roots of welds.

TOFD method is very useful for testing thick-walled components as the achievable testing speed drops only very slowly with the raising thickness.

When testing with TOFD method, a continuous record of the measured data is always performed, which is subsequently saved into the device memory. After saving, this record can by analyzed either directly on the display of the measuring device or later on an external computer.

TOFD records has a very high level of repeatability, one of the highest among the other NDT methods. For this reason, TOFD is a very useful method for repeated measurements, in order to determine the possible growth of defects over time.