Phased array ultrasonic testing (PAUT)is a non-destructive testing (NDT) technique that uses an array of ultrasonic transducers that are each capable of independently emitting and receiving soundwaves. By arranging multiple probes into groups of elements it is possible to complete detailed and highly customisable inspections.
Each phased array probe is able to transmit an ultrasonic beam to a focal spot at different beam angles and depths. By precisely controlling the time delays at which each of the elements in the array sends its signal, it is possible to create display data images of different cross sections, such as a ‘side view,’ ‘end view,’ or ‘top view.’ The timing (or phase) of these electronic scanning signals allows for beam steering that makes phased array testing highly effective for detecting flaws, measuring flaw dimensions, and assessing weld quality.
Common applications include weld inspection (detecting cracks, porosity, or fusion issues), corrosion mapping (assessing wall thickness in pipes and tanks), detecting delamination and other issues in composites, time-of-flight diffraction (ToFD) to size defects.
The transducer arrays can be arranged into different configurations for different purposes. Standard linear arrays are widely used in pipeline and more general inspections while matrix arrays allow for the inspection of more complex geometries.
PAUT probes allow for electronic focusing, scanning, and steering, of the sound beams without moving the probes, providing faster inspections and better flaw characterisation than with conventional probes.
Additional techniques include mechanical scanning PAUT, which uses a mechanical device, such as a scanner, to move a PAUT probe across a surface, to provide a precise, repeatable, and automated way to collect data over even larger areas, such as pipeline girth welds, pressure vessels, or complex composite structures.