Phased Array Testing of Welds
PRINCIPLE
Phased array testing is the same technology as used in medical ultrasound and displays the results in a sectorial scan showing the beam sweep over a range of angles as show in figure above. The method is an extension of the conventional ultrasonic NDT method. Instead of a single-element probe, phased array uses multi-element probes, typically 16, 32 or 64 elements. The elements are pulsed individually with programmed time delays to control the beam steering and focusing. Beam steering allows the beam to sweep over a range of angles and produce a image rather than using fixed angles as in conventional UT. Instead of using three conventional probes, 45°, 60° and 70°, the PAUT beam is typically swept over a range from 40° to 70° to illuminate the weld volume as shown above by the shaded area (1). See our article in Quality Magazine, July 2023, Phased Array Ultrasonic Testing – A Tutorial
EQUIPMENT
PAUT scanner with DLA probe on stainless steel weld
PAUT can be applied in manual mode or in scanning mode. Scanners include a encoder to record position information with the raw data. Once recorded and saved, data can be displayed in various cross-sections to analyze the weld volume. Phased array equipment includes: PA machine 32:128 or 64:128, phased array probes, and scanner. Probe selection and PA setup are very important for a reliable inspection (2).
APPLICATIONS
Phased array UT is used for flaw detection in test materials and welds. The sectorial scan display of phased array makes the technique easy to interpret for the technician and a more reliable test compared to conventional UT.
REFERENCES
1. Anmol Birring, Ultrasonic Phased Arrays for Weld Testing, Materials Evaluation, March 2008
2. Anmol Birring, Optimizing Probe Active aperture for Phased Array Weld Inspections, Materials Evaluation, Aug 2021
TRAINING
Level II – 80 hours
Prerequisite – UT Level II
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