AUT inspection of small bore piping welds


The advantages of Ultrasonic inspections above radiographic inspections are comprehensive. Ultrasonic inspections of small bore piping with small thicknesses have always been very interesting to the market but also challenging.

– No evacuation needed for ionizing radiation (no interrupts in welding and other activities)

– Fast inspection

– Eco-friendly

– Instant inspection result (no development time of films)

– No licenses needed for radiographic testing

– No storage costs for radioactive sources

– Inspection results digitally stored

Next to a small diameter there is also the limited thickness which brings in a second challenge to perform an ultrasonic inspection. Limited wall thickness of < 6mm are not covered under the codes and standards, meaning that the inspections approach needs to be validated.

TRS has developed and validated two inspection approaches to inspect these small bore piping, which are:

– Phased Array inspection with special low profile scanners and probes.

– Special Asterix AUT inspection with integrated probe and scanners and dedicated software and hardware.

The inspection approach with Phased Array is performed with a special scanner, which can cover a diameter from 21.5 to 115mm. Each diameter within this range can be inspected with this system. Depending on the type of material the correct low profile probe can be selected.

Due to the small size of this system inspection of only 11mm, small clearances between piping can be inspected in an efficient way. The system has a quick release locking mechanism, allowing us to set up the system very fast and perform the inspection on a large number of welds.

All data of the inspection is digitally stored for efficient inspection and to perform quality reviews of the data. Next to this Phased Array inspection system, which is reliable and accepted in the NDT market we strive to improve the quality level of our inspection.

We have noticed that although this Phased Array inspection is accepted in the market, there is still a need to improve this inspection method. Especially the possibility to look for transfer cracks perpendicular to the scan direction and indications in the root penetration area is still a demand which could not be met with the current ultrasonic techniques. To cover this part of the inspection, which in many cases is not fulfilled we have developed a complete new inspection system.

Transfer crack propagation on stressed component.

Our special AUT Asterix system has been developed to cover the complete range from longitudinal and transverse indications in the complete weld, including the root area. The Asterix system consists of dedicated hard- and software and an integrated scanner and probe which can be placed extremely fast and inspect a small bore pipe weld within minutes.


Outer diameter: Ø ¾“ (19mm) to Ø 4“ (100mm)

Wall Thickness: 2,6 to 6,4 mm

We have developed this system to be able to inspect tens of thousands of welds within large heat transfer systems where the accessibility is extremely limited.

The system has been tested on small bore piping with dimension from Ø19 to 100mm and wall thicknesses from 2,6 to 6,4 mm. Our dedicated software system has been developed to handle the enormous amount of inspection data in an efficient and clear manner.

This systems has been developed and patented in close cooperation with NEM Energy Systems B.V. / Siemens Heat Transfer Technology.

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