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Yijingtong Testing Technology (Beijing) Co., Ltd
Utilize EVIDENT's new advancements in the field of corrosion detection to overcome challenges in terms of environment and accessibility!
Date: 2025-08-15Read: 3
When searching for high-quality portable non-destructive testing (NDT) tools for remote or restricted area testing, the following important criteria should be considered:
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Easy to install and operate
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Reliable and high-quality results
To obtain high-quality signals during phased array ultrasonic testing (PAUT), it is necessary to ensure that sound waves can be uniformly transmitted into the tested component. Good coupling between the probe and the workpiece surface is a key factor in achieving this goal. Before selecting a coupling system for detection, it is necessary to consider the condition of the workpiece surface. For severely corroded and uneven surfaces, it is best to use local water immersion detection technology, but for smooth surfaces, harder wedges may be more advantageous.
In this article, we will discuss these surface types and provide an overview of the solutions Evidence offers for these situations.
The advantages of local water immersion technology
During on-site maintenance and inspection, a local water immersion scanning system (such as the HydroFORM scanner equipped with I8 phased array probe in Evident) is a solution that can provide stable coupling effects. Its low flow water layer is equipped with foam gasket, which can be attached to the workpiece to maintain a good coupling state with the surface, even on curved or irregular measured surfaces (such as pipes, tanks and welded joints). However, this localized flooding system requires an external water supply system to provide water.
The desire to obtain a constant water flow when conducting testing in remote areas or detecting difficult to reach targets may be impractical or impossible to achieve. In certain special circumstances, considering pollution issues, relevant environmental regulations may also prohibit the use of free flowing liquids.
What should I do when the water flow is' blocked '?
In order to simplify the detection that can only be carried out through rope climbing, the REX2 DLA and HydroFORM solutions only require a small amount of coupling agent to complete corrosion imaging.
The spring loading mechanism of REX2 DLA helps to maintain continuous contact between the Rexolite delay block of the probe and the surface, ensuring reliable sound wave propagation without external water supply.
Efficient and multifunctional scanning solution
The aperture of REX2 probe is twice that of REX1 DLA probe, which has all the advantages of DLA probe (such as higher data point density than traditional twin crystal UT probe), as well as other advantages:
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The sound beam has a larger coverage range and higher scanning efficiency.
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Due to the increase in resolution, the detection rate (POD) also increases.
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When used in conjunction with the HydroFORM scanner, coding scanning can be easily performed.
Compared with linear probe technology, DLA probes use emitting and receiving chip arrays with angles and acoustic isolation characteristics, which can obtain smaller focal points closer to the surface of the measured workpiece. Therefore, compared with linear phased array probes, using DLA probes to scan images results in smaller defect stretching, making the quantitative accuracy obtained in the scanning direction more reliable.
In addition, DLA design significantly reduces the amplitude of surface reflections, improves near surface resolution, and allows you to see key defects closer to the surface.
The array installed at a certain angle in the DLA probe adopts a one transmitter one receiver technology, which significantly reduces interface echoes and improves near surface resolution.
According to application requirements, customers can choose multiple options when ordering REX2 probes:
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1 ° or 5 ° roof angle (depending on the thickness of the workpiece)
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Dual crystal 32 chip array (when balancing speed and cost)
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Dual crystal 64 chip array (prioritizing imaging and resolution)
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To improve the coupling effect on the surface, multiple wedges with different AOD curvatures (SREX2 series) can be selected
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You can choose between a cart or a scanner: a cart with wheels (compatible with Mini Wheel encoder) or an XY axis encoded HydroFORM scanner with ScanDeck module.
REX2 DLA probe (left image); REX2 DLA probe installed on the car (middle picture); The REX2 DLA probe installed on the HydroFORM scanner (as shown on the right). The wheel stabilizers of both systems can make scanning smoother.
Perform manual, semi-automatic, or automatic scanning
You can use REX2 in conjunction with car accessories for manual scanning, or integrate it into the HydroFORM scanner to give this semi-automatic solution DLA functionality.
The OmniScan X4 flaw detector is used in conjunction with the REX2 DLA probe installed on the trolley for testing, which is equipped with a Mini Wheel encoder.
The REX2 dual crystal linear array probe is installed in the HydroFORM scanner with XY axis encoding function and ScanDeck module.
After installing the probe into the HydroFORM scanner, you can install the components onto the electric MapROVER scanner to expand the REX2 DLA probe's ability to detect pipelines and achieve high-throughput automated corrosion imaging. You can also install the components onto the SteerROVER scanner for remote detection.
A powerful scanning combination device that integrates HydroFORM and SteerROVER scanners.
Using TFM and PCI technology for accurate detection and
Measuring Challenging Corrosion Mechanisms
Like the REX1 probe, the PR wiring of the REX2 DLA probe has been optimized to meet the complex focusing requirements of the OmniScan X4 flaw detector's Full Focusing Mode (TFM) and Phase Coherent Imaging (PCI).
After being equipped with the REX2 DLA probe, the HydroFORM scanner can use TFM and PCI capabilities for corrosion imaging, providing high-resolution images for damages that are usually difficult to detect, such as pitting or cracks in the vertical direction. You can also utilize the high sensitivity of TFM and PCI to detect complex, smaller pits and defects, such as H2S induced cracking (also known as hydrogen induced cracking or HIC), which may not be detectable otherwise.
Phase coherence imaging (PCI) images of hydrogen induced progressive cracking (HIC) obtained using OmniScan X4 flaw detector and HydroFORM scanner equipped with REX2 DLA probe
For inspectors who wish to obtain an efficient and easy to implement corrosion detection solution for detecting relatively smooth surfaces, REX2 is a choice worthy of serious consideration. When used in conjunction with the HydroFORM scanner and OmniScan X4 flaw detector, the REX2 DLA probe has the following advantages:
For applications where water layers are not suitable or impossible to use, it is an ideal alternative to local flooding technology. In applications with stricter requirements for near surface resolution, it can assist you. It helps you utilize advanced technologies such as TFM and PCI to discover damage mechanisms that are difficult to detect.
