Advancement in Ultrasonic Testing | PAUT

Advancements in Ultrasonic Testing- PAUT

PAUT technology has resulted in easier analysis and less interpretation of A-scan patterns, better accuracy, resolution, and 3D imagery.

Remembering that ultrasonic inspection is stochastic in nature i.e. immediate result, the more data we have, the more accuracy we can determine the quality parameters.

There are various methods of data acquisition, including total focusing method (TFM), matrix arrays, electronic scanning, and multi-salvo techniques. Full matrix capture (FMC) and TFM, the most comprehensive techniques, did not become a portable option until 2014 when computing power became adequate. Prior, it was an offline function only.

The technology has evolved to allow for high-temperature in-service inspection. The future, however, is in the software. Hardware will become standardized, but the software and user interface elements will be the core advancements going forward. The current expansion of PAUT, TOFD, and FMC/TFM will undeniably result in the further evolution of these technologies, hence it benefits in resolution and accuracy, along with applications.

FMC/TFM is currently the highest level of commercially viable in phased array technology. This method offers higher resolution, accommodates mode conversions, and gives high-resolution imagery of indications and profile morphology.

Weld Inspection

PAUT is especially suited for weld inspection. The technician can simply put the weld profile in the program along with dimensional offset info, and once it’s scanned, it will show the exact location of an indication, which from a welding perspective tells the welding engineer where problems are occurring.

If it’s a fracture mechanics-based acceptance criteria, this will have higher accuracy and allow the welder to understand where they are making mistakes. Hence from an engineering perspective, it provides a lot more information to inform future designs and make smarter decisions on whether defects will cause problems or not.

Electronic scanning is primarily used for scanning geometric surfaces on weld profiles or at fixed depths. This method deploys all of the available beams to concurrently hit a geometric profile or a portion of that profile at a specific angle or position if there are areas of concern. With PAUT, the technician has the flexibility to use from four to 64 elements; these numbers could potentially grow in the future, depending on the need.

From a simple weld inspection standpoint, our obligations are to do a full geometric and volumetric examination; anything less is considered an incomplete inspection.

Beyond welding, PAUT is also being used for corrosion assessment as well as testing on complex geometries, flange face corrosion, bolts, pulsation dampers, and anything with a configuration that is not traditional or uniform. The technician performs a blanket scan and the software is able to stitch it all together to end up with an appropriate view, which when combined within the software, essentially provides a 3D image.

PAUT, particularly for weld inspection and corrosion detection, offers a high probability of detection that can discriminate defects versus geometric ghosting. Having all the data and images also provides an auditable trail.

Corrosion Morphology

Corrosion Morphology, with the latest technology, FMC/TFM, the technician can fire 64 elements independently and establish tens of thousands of points/pixels in a defined area and interrogate every one by firing each crystal and the receiving responses on all the others explained. This builds a massive database of responses. Once geometries are put in as part of the TFM, it can determine what each point represents. Once a scan is done, technicians can use many different configurations to gain different insights because the data has already been accumulated in the area of interest. The data can be used to configure any scan or transferred digitally to anywhere it is needed. Data files for TFM are well into the gigabyte realm as opposed to a standard PAUT scan, which is in the hundreds of megabytes range. Crawford noted that industry has been using this technology since 2015, but it has only just made the ASME codes this year.

Advanced Technology

The next wave Of PAUT technology being more automated. Historically, when a weld was inspected with PAUT, technicians would review the weld scan, evaluate areas of concern, and report it. This usually was done over an extended period of time or a night shift. But automation and integration allow for all these tasks to be done in an accelerated manner to increase production, which will help improve productivity, quality, and safety. Now a day’s engineers are aspiring to with PAUT is digital twinning where we would put a technician in the field who doesn't necessarily need to have the advanced technical skills but rather applies an approved and tested application designed by a level 3 and implements it with their operability skill set. In the shop or office, another technician could monitor his or her activities and implementation by a video that would be tied through a connected device. So you could see what the on-site technician is seeing, and if there are any issues, you can relay that back to them. This allows it to be done anywhere in the world. It is believed digital twinning will continue to be adopted for cost and productivity reasons.