Phased Array Ultrasonic Testing [PAUT]

PAUT utilises 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 motorised 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.

There are several advantages of PAUT that include, but are not limited to:

• Record keeping: permanent digital records accessible to everyone are generated
• 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.
• Coverage: by steering, focusing, and scanning the transducer beams, PAUT systems can be used to inspect large surface areas quickly with high resolution.

The key disadvantages of this testing method are:

• A higher initial cost: compared to conventional ultrasonic testing systems. However, as in every investment, PAUT will, long-term, result in faster, more accurate and efficient inspections maximising asset uptime, leading to a lower total cost of ownership.
• Difficult operation and data interpretation: therefore specially trained personnel is required, in order to eliminate the risk of inaccurate testing and to use the equipment to its full potential.

PAUT can be used to inspect almost any material where traditional UT methods are beeing utilised and is often used for weld inspections and crack detection.

As an advanced NDT method, PAUT is used to detect discontinuities to determine component quality, making it ideal for:

• Weld Inspections
• Thickness Measurements
• Corrosion Inspection
• Inspection of Rolling Stock Wheels and Axles
• Pressure Vessels
• Tanks