Phased Array Ultrasonic Testing
Phased Array (PA) technology provides many advantages over conventional UT and X-ray methods of inspection. Many different elements are aligned in a single transducer housing and excited at different time intervals to produce different acoustic phenomenon in a test piece. Imaging of the piece can then be viewed in digital representation using A-Scan, B-Scan, C-Scan, and Sectorial Scan (S-Scan). When applied correctly, utilizing PA's can be faster than conventional X-ray and shearwave methods, while collecting more sensitive data and images allowing for defect location, characterization, and sizing (both in length and thru-wall height).
Phased Array technology is the ability to electronically modify the acoustic probe characteristics by utilizing many elements in specific patterns of excitation to produce a desired ultrasonic wave pattern in a test piece. Generation of uniform wave fronts, beam focusing, and the ability to utilize many different ultrasonic angles at once give the user the ability to perform multiple types of inspections at once. Any UT technique for flaw detection and sizing can applied using Phased Arrays.
Phased Arrays are extremely useful when examining difficult geometries and other parts where conventional shearwave methods and X-rays cannot produce acceptable results. Detection and sizing accuracy greatly increase with the ability to focus sound at specific points inside the test piece. Several Inspections can be performed at once using only one transducer. Phased Array inspections include but are not limited to: pipe and pressure vessel weld examinations, nozzle and penetration weld examinations, turbine disk blade root inspections, raised face and ring-joint flange inspections, prove-up for primary inspection techniques such as Time-of-Flight-Diffraction, and supplemental prove-up techniques are available for hydrogen damage such as HIC/SOHIC inspections. Phased Array technology also allows for tandem scanning in one array for the inspection of vertical fusion faces in narrow gap welds, such as J-bevel for heavy walled reactors. PA can be applied to an automated or semi-automated systems allowing for fast inspection times and repeatability for long term monitoring projects.