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Brand: Dakota NDT
Dakota Shear Wave Transducers (Standard) for Flaw Detectors
Description
Overview
Dakota Shear Wave Transducers in the Standard series are large single element probes designed to be mounted on angle beam wedges for flaw detection. On their own they generate a longitudinal wave; once fixed to a wedge, the sound enters the test piece at an angle and is converted into a shear wave that travels diagonally through the material. This is the standard technique for finding lack of fusion, cracks, porosity and incomplete penetration in welds that cannot be seen from the surface.
As the official authorized partner and exclusive regional representative for Dakota NDT, Seven Star LLC supplies the full Dakota Shear Wave Transducers range to inspection contractors, fabrication yards, refineries and plant integrity teams across Oman and the GCC, with local technical support.
Measurement Principle
Angle beam testing relies on refraction at the boundary between the wedge and the steel. The wedge holds Dakota Shear Wave Transducers at an incident angle chosen so that, inside the part, the longitudinal component is eliminated and a shear wave travels at the nominal refracted angle of 45, 60 or 70 degrees. When that beam meets a reflector such as a crack face or a fusion line defect, part of the energy returns along the same path to the transducer and appears as an indication on the flaw detector screen.
Because the beam travels at an angle, the instrument must convert sound path into surface distance and depth. Dakota flaw detectors use a trigonometry function that takes the refracted angle, material velocity and part thickness into account and reports the sound path, surface distance and depth of the reflector. Correct calibration on a reference block before inspection is therefore essential.
In practice, the inspector couples Dakota Shear Wave Transducers and their wedge to a reference block and confirms the beam index point, where the sound leaves the wedge, and the actual refracted angle in steel. The time base and sensitivity are then set using known reflectors such as side-drilled holes or the radius of the block. Only after these checks does scanning of the weld begin, moving the probe in a raster pattern so that the beam sweeps the full weld volume and heat affected zone.
Engineering Design of the Dakota Shear Wave Transducers
The Dakota Shear Wave Transducers Standard series uses square or rectangular elements of 1/2 x 1/2, 1/2 x 1, 5/8 x 5/8, 5/8 x 3/4 and 3/4 x 3/4 inch, fitted with BNC connectors. Each probe is fixed to its wedge with two screws, giving a rigid acoustic coupling between transducer face and wedge. Larger elements produce a longer near field and a more powerful, less divergent beam for thick sections, while smaller elements fit tighter scanning areas.
Three damping characteristics are offered. High gain damped probes (G) emphasise sensitivity for detecting small reflectors at longer sound paths. Resolution probes (R) produce shorter pulses that separate closely spaced reflectors near the surface or root. Composite probes (P) use a composite element that offers a good signal to noise ratio on attenuative materials. The 2.25 MHz range is the general purpose choice for weld inspection of thicker plate, while the 5.00 MHz range gives better resolution on thinner sections.
Key Features
Dakota Shear Wave Transducers combine with Dakota flaw detectors to provide a complete angle beam toolkit:
- Frequencies of 2.25 MHz and 5.00 MHz for general weld inspection.
- Element sizes from 1/2 x 1/2 inch up to 3/4 x 3/4 inch.
- High gain, resolution and composite versions to suit sensitivity or resolution needs.
- Rugged BNC connectors for secure cable connection on site.
- Two-screw wedge mounting for stable, repeatable coupling.
- Compatibility with Dakota 45, 60 and 70 degree standard and AWS snail wedges.
- Designed for the trigonometry function of the FX70, FX71, FX80 and FX81 flaw detectors.
- Usable for butt welds, fillet welds, nozzle welds and forging inspection.
Industrial Applications
Dakota Shear Wave Transducers are used for weld inspection on pipelines, pressure vessels, storage tanks, structural steel and offshore structures. In oil and gas facilities they support new construction acceptance testing and in-service inspection of welds for fatigue cracking. Fabrication shops use them to verify welder qualification coupons and production welds, and power plants use them on boiler and piping welds during outages.
As the officially authorized partner for Dakota NDT, Seven Star LLC supplies Dakota Shear Wave Transducers to inspection service companies, EPC contractors and in-house quality departments throughout Oman and the wider GCC, including Muscat, Sohar and Salalah, and pairs each probe with the correct wedge angle and calibration block for the customer’s procedure.
Technical Specifications
The Dakota Shear Wave Transducers part numbers below are taken from the Dakota NDT product page.
| Parameter | Specification |
|---|---|
| Model | Dakota Shear Wave Standard Transducers |
| Connector | BNC |
| Compatible instruments | Dakota FX70, FX71, FX80, FX81 |
| 2.25 MHz, 1/2 x 1/2″ | T-8044-1848 (G); T-8044-1858 (R) |
| 2.25 MHz, 1/2 x 1″ | T-8084-1848 (G); T-8084-1858 (R) |
| 2.25 MHz, 5/8 x 5/8″ | T-8054-1848 (G); T-8054-1858 (R); T-8054-1868 (P) |
| 2.25 MHz, 5/8 x 3/4″ | T-8094-1848 (G); T-8094-1858 (R); T-8094-1868 (P) |
| 2.25 MHz, 3/4 x 3/4″ | T-8064-1848 (G); T-8064-1858 (R) |
| 5.00 MHz, 1/2 x 1/2″ | T-8044-2848 (G); T-8044-2858 (R) |
| 5.00 MHz, 5/8 x 5/8″ | T-8054-2848 (G); T-8054-2858 (R); T-8054-2868 (P) |
| 5.00 MHz, 5/8 x 3/4″ | T-8094-2868 (P) |
| Damping key | G = high gain damping; R = resolution; P = composite |
How to Order
Seven Star LLC processes formal RFQs for all Dakota Shear Wave Transducers, with lead time confirmed at quotation and technical data available on request from our instrumentation division. Share your inspection procedure, material thickness and flaw detector model, and we will match the probe, wedge and reference block, whether you use the Dakota FX70-DL ultrasonic flaw detector, the Dakota FX81-DL bench-top flaw detector or need Dakota calibration blocks for calibration. As the authorized partner for Dakota NDT in Oman and the GCC, we supply probes on request with lead time confirmed at quotation.
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About brand
Ultrasonic thickness gauging is the core of Dakota NDT, the Scotts Valley, USA maker that many inspectors still know as Dakota Ultrasonics. Its instruments measure remaining wall on corroded pipe and vessels, check precision parts, find flaws in welds and monitor bolt elongation.
Seven Star LLC is the Dakota NDT agency for Oman and the GCC. We list Dakota corrosion and precision thickness gauges, flaw detectors, transducers, delay line tips and calibration blocks, and supply them with the manufacturer's documentation.
Dakota NDT product families
Corrosion thickness gauges form the largest group: the CMX10-DL with full waveform capture, the CMX, CX and ZX series and the MX2-DL. For thin or tight-tolerance material Dakota builds the precision line, made up of the PZX1-DL, the PCX8-DL and the PMX series. The RX8-DL sonic tester, the PMX4-DL and the R9 sit in the specialty group. Flaw detection is handled by the handheld FX71-DL and the bench-top FX81-DL, and bolt tension by the BT1-DL, the BT2-DL and the MultiMax remote monitoring system. Dual element transducers pair with corrosion gauges, single element and delay line probes with precision gauges. DakMaster and DakView software take care of data transfer and reporting.
Where Dakota ultrasonic thickness gauges are used
Typical jobs are wall-loss surveys on pipelines, tanks, boiler tubes and pressure vessels in oil and gas plants and power stations, thickness checks on machined, drawn or molded parts, weld inspection in fabrication shops, and bolted joints on flanges and turbines where clamp load matters more than torque.
Ordering Dakota gauges and probes: what we need
A useful inquiry names the gauge model, the material, its expected thickness span, the surface temperature and whether the surface is coated. For transducers send the frequency, element diameter, connector type and the gauge the probe will be used with. For calibration blocks give the material and the step sizes you need. If you already own a Dakota instrument, a photo of its label and of the current probe lets us check the match against the manufacturer's documentation.
Related products
Frequently Asked Questions
What are Dakota Shear Wave Transducers used for?
They are used with angle beam wedges for ultrasonic flaw detection, mainly weld inspection. The wedge converts the sound into a shear wave that travels at 45, 60 or 70 degrees through the part to find cracks, lack of fusion and porosity.
Should I choose 2.25 MHz or 5.00 MHz?
The 2.25 MHz probes are the general purpose choice for thicker welds and more attenuative materials, while 5.00 MHz probes give better resolution on thinner sections and finer defects.
What do G, R and P mean in the part numbers?
G indicates a high gain damped transducer for sensitivity, R a resolution transducer with a shorter pulse, and P a composite transducer with a good signal to noise ratio.
Which flaw detectors are compatible?
The Standard shear wave transducers use BNC connectors and are specified for the Dakota FX70, FX71, FX80 and FX81 flaw detectors, which use a trigonometry function for angle beam calculations.
Is Seven Star LLC an authorized representative for Dakota NDT products?
Yes. Seven Star LLC is the officially authorized partner and exclusive regional representative for Dakota NDT in Oman and the GCC, supplying genuine transducers with local technical support.
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