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Phased Array Ultrasonic Testing (PAUT)

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Phased Array Ultrasonic Testing (PAUT) is an advanced nondestructive examination technique that utilizes a set of ultrasonic testing (UT) probes made up of numerous small elements, each of which is pulsed individually with computer-calculated timing (“phasing”). When these elements are excited using different time delays, the beams can be steered at different angles, focused at different depths, or multiplexed over the length of a long array, creating the electronic movement of the beam. Phased array probes can be used manually in a free running mode scrubbing the surface of a component, attached to an encoder to record position, or mounted on a semi-automated or motorized scanner for optimum productivity. Using phased array probes in direct contact with the component, whether mounted on a hard wedge, a water delay line, or even inside a wheel probe, gives inspectors the ability to quickly scan large areas for corrosion, cracking, and other defects with high resolution. PAUT can be used to inspect almost any material where traditional UT methods have been utilized and is often used for weld inspections and crack detection. 

Notable Advantages of PAUT 

  • COVERAGE:  By steering, focusing, and scanning the transducer beams, PAUT systems can be used to inspect large surface areas quickly with high resolution. 
  • SPEED:  Rapid coverage of larger surface areas means PAUT can typically be conducted more quickly than conventional UT.
  • ACCURACY:  By emitting beams of multiple different angles sequentially, PAUT is able to create detailed and accurate cross-sections of an asset, thereby increasing the probability of detecting anomalies.
  • REPEATABILITY:  PAUT can easily be used for repeat scans due to its high degree of accuracy and consistency. 
  • FLEXIBILITY:  PAUT has proven to be an effective technique for inspecting more complex geometries such as elbows, bends, and nozzles. PAUT is also particularly useful in situations where there is limited access for mechanical scanning because it’s able to sweep the beam without moving the probe.
  • SAFETY:  Using a semi-automated or motorized PAUT scanner avoids exposing inspection personnel to potentially dangerous environments. Moreover, PAUT is an effective alternative to radiographic testing, eliminating the safety hazards associated with radiography.

Notable Disadvantages of PAUT

  • COST:  Compared to conventional ultrasonics, PAUT may require a greater initial investment in equipment and experienced technicians, however these costs are frequently offset by the increased flexibility and a reduction in the time required to perform a given inspection. 
  • TRAINING:  PAUT often requires additional operator training to ensure the effectiveness and accuracy of the inspection results.

Industry Applications

  • Weld inspections (pressure vessels, piping, and tubing)
  • Crack detection (HIC, SOHIC, and SCC)
  • Inspecting composite materials
  • Corrosion mapping
  • Flaw sizing for remaining life calculations


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