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Ultrasonic Weld Inspection using TWI Crystal and Peak NDT’s LTPA/MicroPulse Units


Peak NDT is a world-leading designer and manufacturer of high performance conventional and phased-array ultrasonic instrumentation used for non-destructive testing (NDT), in advanced engineering sectors. For over 35 years Peak NDT’s MicroPulse technology has been used at the forefront of NDT ultrasonic technique development from high-performance multi-channel conventional technology to Phased Array (PAUT) and now Full Matrix Capture (FMC) and other advanced techniques.

TWI have developed an advanced ultrasonic FMC inspection software called TWI Crystal™ using the Peak NDT hardware as the primary data acquisition system. It supports a comprehensive feature set allowing it to be deployed within a number of many industrial sectors including, oil and gas, rail and aerospace among others.

The project

Structural integrity inspection of pipeline girth welds is crucial to maintain the continuous flow of resources from the production site to the user. Ultrasonic testing plays a vital role in managing the integrity of millions of miles of pipeline across the globe. Using post-processing algorithms to interpret ultrasonic data can help simplify the inspection process.  These algorithms can be used to view the data in ways not considered before, improving the way in which flaws can be detected and sized, while also increasing the variety of flaw types that can be found.

Phased array ultrasonic testing (PAUT) and conventional ultrasonic testing (UT) have been used for the inspection of pipeline girth welds for decades. However, recent developments in computer hardware allow for real time inspection capability using total focusing method (TFM) based algorithms, such as Full Matrix Capture (FMC), Plane Wave Imaging (PWI) and Virtual Source Aperture (VSA). These algorithms process the ultrasonic data to synthesise a PA focal spot at every pixel in an image, giving a fully focused, easily interpreted image.

TWI developed a new set of data interpretation and processing features to allow volumetric merging of multiple data sets in real-time.  These included data collected from the upstream channel, downstream channel and a new pitch-catch channel (where ultrasound is transmitted upstream and collected downstream). The objective was to develop an easy to use inspection solution to fully visualise the interior of a girth weld in common pipeline samples using a number of processing algorithms. Each channel supports up four multi-mode visualisations (selectable from 24 different configurations) with data from all channels being volumetrically merged with intendent calibration and soft-gain values.

A demonstration video can be seen below:


Through collaboration with Peak NDT, TWI has developed a commercial software package for advanced ultrasonic imaging of NDT data using the MicroPulse and LTPA hardware. One unique feature of the software is the ability to image the full interior of common welds using the FMC-pitch catch method. This software is commercially available and is regularly used for inspection applications across a range of industries.

For more information on TWI Crystal, please contact Crystal@twi.co.uk, or visit: