Array probes use a number of small coils to replace a rotating head, rotating probe, or
one axis from a two-axis surface scan. This greatly accelerates the inspection process and
overcomes many scanning limitations. R/D Tech equipment makes eddy current array
probes affordable, portable, and less susceptible to mechanical failure.
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Inspection of Bars, Tubes, and Rods
 Array probes for in-line inspections are able to inspect tubes and bars of all shapes and profiles. |
R/D Tech's powerful ECT array coil equipment brings together the best of both worlds: it provides high speed and reliable detection of small volume flaws as well as of long flaws, while having no moving parts.
- No moving parts
- Very high speed: 10 times faster than rotating probes
- Good for short and long flaws
- Adaptable to non cylindrical parts
Inspection of bars, tubes, and rods
| Rotating probes | Encircling probes | Array probes | |
| Detection of short flaws | No | Yes | Yes |
| Detection of long flaws | Yes | No | Yes |
| Detection of small flaws | No | No | Yes (down to 0.05 mm depth, 0.5 mm Ø on product of any Ø) |
| Inspection speed | Slow (short flaws) | Fast | Fast |
| Rotation speed | <10,000 r/min | N/A | >90,000 r/min (~x10) |
| Adjustable diameter | Yes | No | Yes |
| Detection of circumferential flaws | Yes | No | Yes |
| Adaptable to non cylindrical shape | No | No | Yes, any |
| Automatic flaw detection | Yes | Yes | Yes |
Weld Inspections
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- Inspection of weld without surface preparation
- Detection and sizing of surface-breaking cracks on weld and heat-affected zone
- Single pass along weld reducing noise compared to raster scan
Automated Surface InspectionsArray-coil scans can also replace liquid penetrant inspections, producing results much faster and without any chemical handling. The resulting image can be printed on any PC-compatible printer, or archived to disk.By greatly reducing the number of scan lines, array probes increase the speed of automated scanning of surfaces such as turbine retaining rings, reactor pressure vessels, welds, etc. Furthermore, ultrasound scanning can be performed simultaneously.
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Inspection of Complex SurfacesArray probes can be produced for a variety of shapes, allowing fast inspections, full data logging, and simple probe handling systems.
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Figure 1:
A 50-coil array probe inspection is more than 50 times faster than a raster
scan made using a small ECT coil. Probe handling is also much simpler.
This plate was scanned in less than one second and the complete image
was produced immediately after the scan was completed.
ECT array probes versus liquid penetrant
| Liquid penetrant testing | ECT array probes | |
| Inspection speed | Slow, multistep process | Fast |
| Analysis | Simple, visual | Visual, C-scan presentation |
| Repeatability | Fair | Excellent |
| Discrimination | No distinction between scratch and crack | Less sensitive to surface finish |
| Subsurface flaws | Not detected | Detected |
| Flaw depth sizing | No | Yes |
| Chemicals and waste | Uses chemicals and produces waste | Clean and dry; no waste or chemicals |
| Automatic flaw detection | Complex, need vision system | Simple |
| Hard copy and archives | Camera picture | Printouts; archives on PC media |