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Ultrasonic Phased Array in Lieu of Radiography

Ultrasonic Phased Array in Lieu of Radiography


Many codes allow for the substitute of one method of stated nondestructive evaluation (NDE) for another as long as certain requirements are met. Other non-code based inspections are constantly being reviewed for cost savings and other improvement to process. One substitution growing in popularity and practice is the substitution of ultrasound where previously radiographic methods were used.


Radiography and ultrasound are two complimentary nondestructive testing (NDT) techniques. Both can volumetrically inspect welds and components for defects like cracks, lack of fusion, porosity etc. The choice of one over the other often comes to external process decisions or small variables in their ability in a particular test. In recent years the use of ultrasound where radiography was typically used has gained momentum in both practice and with major code bodies like ASME (American Society of Mechanical Engineers) and API (American Petroleum Institute). Although most codes do not specify the ultrasonic method, phased array has become the most popular choice when trying to make the replacement in processes. It is often also combined with TOFD (time-of-flight diffraction) since the modern acquisition units and scanners can accommodate both methods simultaneously. For code-based inspections historically these processes were conducted through code cases or appendixes, but after a large amount of industry practice and success they are being codified directly into the main bodies of the major code books as seen in the 2010 and beyond ASME Sec. V. Art. 4. Modern phased array equipment today is highly portable, less expensive, and easier-to-use than ever, making the opportunity to replace radiography with ultrasound easier than ever.

Typical Advantages of Ultrasonic Method vs. Radiography:

  • High probability of detection (POD) especially for cracks and lack of fusion
    • Ultrasound tends to detect planar flaws better than radiography in most studies
  • Accurate sizing of defects height and less rejects/repair using Engineers Critical Assessment
    • Ultrasound allows defect height measurement allowing volumetric consideration of flaw severity vs. just type and length
  • No radiation, hazard, or additional licensing or personnel
  • No screened off areas, work can go on around ultrasonic testing
  • No chemical or waste material compared to film based radiography
  • Real-time analysis for instant evaluation and feedback to welder
  • Setup and inspection reports in electronic format compared to film based radiography

Radiography Replacement with Ultrasound Code Examples

  • ASME Code Case 2235
  • ASME Code Case 179
  • ASME Code Case 168
  • ASME Code Case N-659
  • ASME Code N-713
  • API 620/650 App. U
  • ASME Sec. V Mandatory Appendixes

Typical Equipment and Inspection Requirements

  • Acquisition unit with Full Raw A-scan data retention and encoding ability (OmniScan or Focus LT)
  • Scan plan and procedure showing documented inspection strategy and essential parameters
  • Industrial Scanner (encoder) that repeatedly scan weld or component (Semi or Fully Automatic)
    • Selection based on number of welds, pipe diameter, and other application variables
  • Deliverable data
    • Analysis performed on acquisition unit or post analysis software OmniPC or TomoView
  • Performance demonstration for equipment, procedure, operator and inspection process
  • Alternative acceptance criteria as required
  • Probes, wedges, couplant delivery and other accessories
  • Proper training and certification for personnel
OmniScan MX2 (MultiGroup capable) and OmniScan SX (Single Group)
OmniScan MX2 (MultiGroup capable) and OmniScan SX (Single Group)

Fully automatic WeldROVER and Semi-Automatic Compact Scanner with OmniScan
Fully automatic WeldROVER and Semi-Automatic Compact Scanner with OmniScan

Fully automatic WeldROVER and Semi-Automatic Compact Scanner with OmniScan

NDT SetupBuilder and OmniPC Software for design and analysis
NDT SetupBuilder and OmniPC Software for design and analysis

NDT SetupBuilder and OmniPC Software for design and analysis


Radiography replacement has become an industry trend and code accepted practice. Modern easier-to-use, less expensive portable phased array equipment and associated software has accelerated this practice in recent years. Main reasons for this continuing trend include process cost and time savings, safety of operators and those in surrounding areas, and the use of alternative acceptance criteria leading to less reject and repairs.

Olympus IMS
Products used for this application

NDT SetupBuilder is a new PC-based software allowing to create inspection setup and visualize beam simulations. This software presents multiple features for easy, fast, and comprehensive inspection strategy elaboration that can directly be imported in the OmniScan MX2.
The capacity to accurately position probes according to the surface being inspected greatly influences inspection quality. Olympus offers a wide range of industrial scanners and accessories to assist inspectors in their work. Scanners come in various configurations including one or two encoded axes with manual or motorized motion.
TomoView is a powerful and flexible PC-based software used for design, data acquisition, visualization, and analysis of ultrasonic signals.
This new software is the most efficient and affordable option for OmniScan data analysis, and features the same analysis tools provided in the OmniScan onboard software, with the added flexibility of running on a personal computer.
The single group, lightweight OmniScan SX features an easy-to-read 8.4 inch (21.3 cm) touch screen and provides cost-effective solutions. The OmniScan SX comes in two models: the SX PA and SX UT. The SX PA is a 16:64PR unit, which, like the UT-only SX UT, is equipped with a conventional UT channel for P/E, P-C or TOFD inspections.
The OmniScan MX2 now features a new phased array module (PA2) with a UT channel, and a new two-channel conventional ultrasound module (UT2) that can be used for TOFD (Time-of-Flight Diffraction), as well as new software programs that expand the capabilities of the successful OmniScan MX2 platform.
Phased array application-specific probes have a range from 0.5 MHz to 18 MHz and may come with 16, 32, 64, or 128 elements. Special probes may have up to hundreds of elements.
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