PAUT is an advanced method of ultrasonic testing. Instead of a single transducer and beam, phased array uses multiple ultrasonic elements and electronic time delays to create beams by constructive and destructive interference.
As such, PAUT offers significant technical advantages for weld testing and plant monitoring over conventional ultrasonic as the phased array beams can be steered, scanned, swept and focused electronically from a fixed probe position. Beam steering permits the selected beam angles to be optimized ultrasonically by orienting or focusing them perpendicular to the predicted discontinuities, for example lack of fusion in automated weld inspections.
PAUT is now used for inspecting fabricated piping and pressure vessel welds. For piping inspection, it is used in lieu of radiography or manual ultrasonic inspection. The flaw image obtained with multiple angles and beams give a more accurate flaw characterization than conventional ultrasonic inspection. This in turn facilitates fitness for service modelling and predictions.