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Phased Array Ultrasonic Testing

Phased Array Ultrasonic Testing (PAUT) is an advanced NDT method that is often used for weld inspection and crack detection. It can also be used to effectively profile remaining wall thickness in corrosion survey applications.

PAUT systems work by activating several elements independently, each emitting an ultrasonic pulse. The pulses form a pattern of constructive interference, which causes the overall angle of the beam to be focused in a set direction. By pulsing the elements in different ways, the beam can be steered and swept electronically, without having to move the phased array probe.


Phased array probes typically consist of a transducer assembly with anywhere from 16 to as many as 256 small individual elements, each pulsing separately. The frequency of these pulses can range anywhere from 2MHz to 100MHz. A PAUT system consists of a computer-based instrument that is capable of driving the multi-element probe, receiving and digitizing the returning echoes, and plotting that echo information in various formats.



  • Pressure vessels: testing of nozzle, circumferential and longitudinal seam welds.

  • Piping: testing of in-service or newly fabricated piping in accordance with applicable codes.

  • Structural Steel: weld quality verification.

  • Wind turbine towers: weld quality verification during the fabrication process and inspection of erected towers.

  • Corrosion mapping: C-Scan examinations on areas where obstructions are present restricting most standard automated crawlers.

  • Crack sizing and detection: the detection of cracking on piping or components with the capability of continued monitoring for growth and propagation.



PAUT systems keep a permanent record of the inspection as it is being performed so that the results can be stored and reviewed at a later date if need be. PAUT is code compliant and it has a better utilization of manpower compared to industrial radiography on shutdowns. Phased array testing is also highly repeatable.

Sentinel’s advanced technicians are equipped with the latest technology which allows them to streamline the inspection process and minimizes downtime. 

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