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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Articles about Phased Array Ultrasonic Testing (PAUT)
November/December 2023 Inspectioneering Journal

A comparative analysis of robotic nondestructive inspection tools used to locate floor defects in aboveground storage tanks.

March/April 2023 Inspectioneering Journal

A look back to when phased array systems were first developed in the 1960s and how the uses and technology have evolved throughout the decades to present day.

September/October 2022 Inspectioneering Journal

Utilizing automated ultrasonic testing (AUT) for corrosion mapping to detect and quantify damage can play an important role in an effective MI program. This article compares two common off-the-shelf AUT technologies used for corrosion mapping.

Authors: Chase David
May/June 2022 Inspectioneering Journal

Resulting from developing a 20-year nonintrusive inspection strategy, a successful experience is presented using a volumetric examination on a modified storage tank shell-to-bottom weld, known in the industry as corner-weld.

May/June 2022 Inspectioneering Journal

The pursuit to develop and validate phased array/time of flight diffraction (TOFD) transducers and corresponding wedges to service high-temperature inspections with the hope to discover reliable, convenient, and cost-effective alternatives.

Authors: Zach Anderson
Partner Content

Are you truly prepared for your next Turnaround? Effective work processes are required to successfully plan, manage, review and supervise plant turnarounds. Inspection planning and work scope selection are critical aspects of any turnaround...

January/February 2022 Inspectioneering Journal

Within one unit, TriLat combines the power of two probes containing three angle beam sets to identify and quantify cracking at early stages. The result is inspection speeds up to ten times faster than traditional AUT systems, depending on probe size.

May/June 2021 Inspectioneering Journal

Hydrogen-induced damage mechanisms have been studied endlessly, leading to changes in equipment design and development of new inspection practices. However, the highly localized nature and difficulty of detection of HTHA add additional complexities.

Authors: Jose Aparicio
May/June 2020 Inspectioneering Journal

This article demonstrates how the use of TFM/FMC can be an effective method to screen for potential problem flanges before a planned shut down and can be a very useful tool in planning which flanges require further evaluation.

Authors: Mark Schramm

Nondestructive testing (NDT) careers are on the rise in today’s economy. These fields are constantly advancing, and there is an ever-growing need for technicians, quality assurance specialists and inspectors as infrastructure in the United States...

Authors: Berg Engineering
Online Article

The availability of high quality UT data is often the cornerstone for FFS and RBI decisions. As such, the API Subcomittee for Inspection and Integrity Management (SCIIM) has initiated a program for the Qualification of Ultrasonic crack Sizing...

Authors: John Nyholt
Partner Content

The OmniScan™ X3 64 phased array and TFM flaw detector is equipped with enhanced phased capabilities and even faster TFM. The rugged and portable instrument features powerful 64-element probes with a 128-aperture TFM.

March/April 2017 Inspectioneering Journal

The purpose of this article is to describe the various in-line inspection (ILI) technologies that are currently available to the market. The pros, cons, and applicability of each type of tool will be discussed in greater detail.

Authors: Matt Ellinger
March/April 2017 Inspectioneering Journal

Ultrasonic phased array allow for a variety of structures to be inspected without radiation or taking equipment out of service. Codes are now being developed which allow phased array systems as an acceptable inspection technique for many procedures.

Authors: Bob Lasser
March/April 2016 Inspectioneering Journal

This article highlights the evolution of corrosion monitoring from conventional ultrasonic to ultrasonic phased array manual and automated solutions and their use for both general purposes and complex applications.

Authors: André Lamarre
March/April 2016 Inspectioneering Journal

While there are many types of advanced NDT, this article will focus on the use of acoustics and electromagnetism as the bases for conducting examinations.

Authors: Mike Brown
November/December 2014 Inspectioneering Journal

The introduction of PAUT is a challenging effort initially, but can have a very positive impact on your first TAR and become a routine inspection for future TARs. When fully implemented, radiation safety boundaries can be reduced significantly or...

January/February 2014 Inspectioneering Journal

Technicians inspecting oil & gas installations and petrochemical plants employ a wide variety of nondestructive testing (NDT) techniques. A new technology has recently been developed that utilizes a real-time portable imaging device which has...

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