Leeb Ultrasonic Flaw Detectors
An ultrasonic flaw detector is a portable non-destructive testing (NDT) instrument that sends high-frequency sound pulses (typically 0.5 to 20 MHz) into metal and other solid materials, and times the echoes that return from cracks, voids, inclusions and lack of fusion. It shows each flaw's depth, position and echo amplitude on an A-scan screen, so welds, castings, forgings, plate and pipe can be inspected without cutting or damaging them.
Ecotao supplies the Leeb range of digital ultrasonic flaw detectors from our Cape Town base, from the entry-level Leeb500 to the IP65 Uee981E with TCG, colour B-scan and AWS weld rating. Below you'll find each model's verified specifications, a side-by-side comparison, a guide to choosing the right one, and answers to the questions inspectors ask most.
How an ultrasonic flaw detector finds a defect
The instrument's pulser excites a piezoelectric crystal in the probe, which sends a short burst of sound into the part through a thin layer of couplant. Sound travels at a known velocity (about 5900 m/s for longitudinal waves in steel) and reflects wherever it meets a change in material. The receiver amplifies the returning echoes and plots them against time. Because velocity is known, time becomes distance, and the flaw can be located precisely.
Every Leeb flaw detector on this page reads out the position of the gated echo automatically. These are the readings the original Leeb literature calls the "four standards":
DDepth
Vertical depth of the reflector below the scanning surface, which tells you how deep in the weld or plate the flaw lies.
PLevel (surface distance)
Horizontal distance from the probe's index point to the point directly above the flaw, used to mark the flaw on the part.
SSound-path distance
Distance the sound beam travelled along its angled path to the reflector, the basic measurement in angle-probe weld testing.
HAmplitude
Echo height, compared with a DAC or AVG reference to decide whether a flaw is acceptable or must be reported.
Straight (0°) probes find laminations and planar flaws parallel to the surface, and measure thickness. Angle probes (typically 45°, 60° or 70°) send shear waves into a weld from the side, which is how cracks, lack of fusion and slag in butt and fillet welds are found.
Leeb ultrasonic flaw detectors available from Ecotao
Four families, from a straightforward A-scan instrument to a high-specification imaging unit. All specifications below come from Leeb's own product data and cover every variant in each family.
Leeb Uee981E Ultrasonic Flaw Detector
Flagship imaging flaw detector for weld and forging inspection
The Uee981E is the most capable Leeb flaw detector. A square-wave pulser with a pulse repetition frequency up to 3 kHz and 320 MHz sampling gives a clean, stable echo even when scanning quickly. DAC, TCG, DGS/AVG and colour B-scan are all standard, along with built-in AWS D1.1/D1.5 weld-rating tools and inspection video recording. Reports are generated on the instrument and exported to USB, or sent to a phone over Bluetooth for on-site printing.
- Frequency range0.2 to 35 MHz
- Scan range0 to 15 000 mm
- Velocity range100 to 20 000 m/s
- Gain120 dB
- Linearity (vert. / horiz.)≤2.5% / ≤0.2%
- Pulse amplitude100 to 500 V
- Protection / standardIP65 · EN 12668-1
- Size & weight240×153×38 mm · 0.98 kg
Also made as the Uee981S (0 to 10 000 mm, 0.2 to 20 MHz) and Uee981O (0 to 12 000 mm, 0.2 to 25 MHz). Ecotao lists the Uee981E; ask us about the other two.
Leeb510 / 520 / 521 / 522 Digital Ultrasonic Flaw Detectors
Colour-screen workhorse series, from basic A-scan to TCG, B-scan and video
One housing, four levels of capability. One-button automatic calibration measures the probe zero, K-value (angle), probe index and the material's sound velocity. A small near-field dead zone makes the series suitable for thin-walled and small-diameter tube. Auto-gain, echo envelope and peak memory speed up scanning. DAC and AVG curves are formed automatically and can be corrected for surface roughness and curvature. Thirteen testing standards are built in, you can enter your own, and inspection reports export to Excel for A4 printing.
- Frequency range0.5–15 MHz (510/520) · 0.5–20 MHz (521/522)
- Scan range0–6000 mm (510/520) · 0–10 000 mm (521/522)
- Gain110 dB (510) · 120 dB (520) · 130 dB (521/522)
- Channels / A-scan storage50 / 500 (510) · 100 / 980 (520–522)
- TCGLeeb521 and Leeb522
- B-scan & videoLeeb522
- Size & weight240×160×40 mm · 1.2 kg
Leeb Uee952 / Uee953 Ultrasonic Flaw Detectors
Rugged IP65 metal-housed units for site and fabrication-shop work
The Uee952 and Uee953 put Leeb's flaw-detection electronics in a durable IP65 metal shell that is sealed against oil, water and dust, which suits mining, steel fabrication and outdoor pipeline work. Both offer automatic probe calibration, automatic DAC and AVG, auto-gain, peak memory, automatic φ equivalent-flaw calculation and 13 built-in testing standards. The Uee953 adds TCG, B-scan, AWS weld rating and video recording, with 500 channels and 1000 stored A-scans.
- Frequency range0.5 to 20 MHz
- Scan range0–6000 mm (952) · 0–10 000 mm (953)
- Gain110 dB (952) · 130 dB (953)
- Channels / A-scan storage100 / 500 (952) · 500 / 1000 (953)
- TCG, B-scan, AWS, videoUee953
- ProtectionIP65 metal shell
- Size & weight240×185×55 mm · 1.85 kg
Leeb500 Digital Ultrasonic Flaw Detector
Simple, robust A-scan flaw detector for routine weld and plate checks
The Leeb500 covers the core tasks of ultrasonic testing without extra complexity. Probe calibration is automatic, DAC and AVG curves build themselves and can be corrected, and the display switches freely between depth (D), level (P), sound-path (S) and amplitude (H) readouts. The φ equivalent flaw size is calculated automatically. Pulse width and intensity are adjustable, 980 A-scan images and data sets can be stored, and PC software handles data management and report printing. The housing is oil-, water- and dust-proof.
- Frequency range0.5 to 15 MHz
- Scan range0 to 6000 mm
- Velocity range1000 to 9999 m/s
- Gain0 to 110 dB
- Sensitivity≥60 dB (200 mm, Φ2 FBH)
- Battery≥10 h continuous work
- Operating temperature−20 to 70 °C
- Size & weight240×160×40 mm · 1.2 kg
Leeb ultrasonic flaw detector comparison table
Specifications for all eight Leeb flaw detector models. “Ask Ecotao” means Leeb's published data does not state the feature for that model, so contact us before relying on it.
← Scroll to see full table →
| Model | Frequency | Scan range | Velocity (m/s) | Gain | Sensitivity* | Vert. linearity | Channels | A-scan storage | TCG | B-scan | Video | AWS tools | Weight |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Leeb500 | 0.5–15 MHz | 0–6000 mm | 1000–9999 | 110 dB | ≥60 dB | ≤4% | Ask Ecotao | 980 | Ask Ecotao | Ask Ecotao | Ask Ecotao | Ask Ecotao | 1.2 kg |
| Leeb510 | 0.5–15 MHz | 0–6000 mm | 1000–15 000 | 110 dB | ≥62 dB | ≤3% | 50 | 500 | No | No | No | Ask Ecotao | 1.2 kg |
| Leeb520 | 0.5–15 MHz | 0–6000 mm | 100–18 000 | 120 dB | ≥62 dB | ≤3% | 100 | 980 | No | No | No | Ask Ecotao | 1.2 kg |
| Leeb521 | 0.5–20 MHz | 0–10 000 mm | 100–20 000 | 130 dB | ≥65 dB | ≤2% | 100 | 980 | Yes | No | No | Ask Ecotao | 1.2 kg |
| Leeb522 | 0.5–20 MHz | 0–10 000 mm | 100–20 000 | 130 dB | ≥65 dB | ≤2% | 100 | 980 | Yes | Yes | Yes | Ask Ecotao | 1.2 kg |
| Uee952 | 0.5–20 MHz | 0–6000 mm | 1000–15 000 | 110 dB | ≥62 dB | ≤3% | 100 | 500 | No | No | No | No | 1.85 kg |
| Uee953 | 0.5–20 MHz | 0–10 000 mm | 100–20 000 | 130 dB | ≥65 dB | ≤2% | 500 | 1000 | Yes | Yes | Yes | Yes | 1.85 kg |
| Uee981E | 0.2–35 MHz | 0–15 000 mm | 100–20 000 | 120 dB | ≥65 dB | ≤2.5% | Ask Ecotao | 1000 groups + USB | Yes | Yes (colour) | Yes | Yes | 0.98 kg |
*Leeb states sensitivity at 200 mm depth on a Φ2 mm flat-bottom hole for the Leeb500, Leeb510 series and Uee952/953. All models share the same standard probe set except the Uee981E; ask us for its delivered kit.
How to choose a Leeb ultrasonic flaw detector
Work through these five questions in order. Each one narrows the range.
How thick is the material, and how far must the beam travel?
For welds and plate up to a few hundred millimetres, the 6000 mm range of the Leeb500, Leeb510, Leeb520 and Uee952 is ample. For long shafts, rolls, large forgings and long-path angle-beam work, choose a 10 000 mm model (Leeb521, Leeb522, Uee953) or the Uee981E at 15 000 mm.
What material and grain structure are you testing?
Fine-grained carbon steel inspects well at 2 to 5 MHz with any model. Thin sections, small flaws and high-resolution work need higher probe frequencies, so pick a 20 MHz instrument or the Uee981E (up to 35 MHz). Plastics, composites and other low-velocity materials need a low velocity limit: 100 m/s on the Leeb520, 521, 522, Uee953 and Uee981E.
How will you evaluate flaws: DAC, TCG or AVG?
Every model forms DAC and AVG automatically. If your procedure calls for TCG, or you want faster evaluation over a long range, you need a Leeb521, Leeb522, Uee953 or Uee981E.
Do you need to rate welds to AWS D1.1 or D1.5?
Structural steel and bridge work to AWS codes is quicker with built-in AWS tools, available on the Uee953 and Uee981E.
What evidence must your report contain?
If a client or inspection authority wants more than A-scan screenshots, B-scan cross-sections and inspection video are on the Leeb522, Uee953 and Uee981E. The Uee981E also exports straight to USB and to a phone over Bluetooth. For harsh sites, the IP65 Uee952/953 metal shell and the IP65 Uee981E give the most protection.
DAC vs TCG vs AVG/DGS: what's the difference?
Sound weakens with distance, so an identical flaw gives a smaller echo the deeper it lies. These three methods compensate for that in different ways.
← Scroll to see full table →
| Method | How it works | Best for | Leeb models |
|---|---|---|---|
| DAC (distance amplitude correction) | A reference curve is recorded from equal-size reflectors at several depths in a calibration block. Flaw echoes are judged against the curve on screen. | Most weld procedures; straightforward to audit | All models |
| TCG (time corrected gain) | Gain rises automatically with depth so equal reflectors show equal screen height, giving a flat reference line. | Fast scanning over long ranges; easier operator judgement | Leeb521, Leeb522, Uee953, Uee981E |
| AVG / DGS (distance gain size) | Probe-specific theoretical curves express a flaw as an equivalent flat-bottom-hole diameter (the φ value). | Forgings and castings; sizing without a matching reference block | All models |
What Leeb flaw detectors do in each industry
Structural steel and fabrication
An angle probe scans butt and fillet welds in beams, columns and plate girders to find cracks, lack of fusion and slag before steel leaves the shop. AWS-equipped models (Uee953, Uee981E) speed up code-based acceptance.
Boilers and pressure vessels
Shell seams, nozzle welds and repair welds are checked at fabrication and during shutdowns. DAC or TCG gives a documented acceptance level, and the stored A-scans form the inspection record.
Power generation and petrochemical
Piping welds, headers and rotating-equipment components are inspected in service for fatigue and thermal cracking, often in hot, dusty plant where IP65 protection matters.
Rail and transport
Axles, wheels and welded rail joints are tested for fatigue cracks. Long scan ranges (10 000 mm and above) suit full-length axle and shaft inspection.
Forgings, castings and machinery
Straight probes and AVG sizing find internal porosity, shrinkage and inclusions in shafts, gears and cast housings before costly machining.
Mining and heavy equipment
Booms, buckets, chassis welds and crusher components are checked for cracks during planned maintenance, extending component life and reducing unplanned stoppages.
Using ultrasonic flaw detectors in South Africa
Operator certification
Inspections that form part of a statutory or quality record, such as pressure equipment, structural steel and pipeline welds, are normally carried out by operators certified to ISO 9712 in ultrasonic testing. In South Africa, this certification is administered through SAQCC NDT.
Pressure equipment
Pressure vessels and boilers in South Africa fall under the Pressure Equipment Regulations of the Occupational Health and Safety Act. Ultrasonic testing of welds is a common part of fabrication and in-service inspection plans under these regulations.
Heat and site conditions
Steel in direct Northern Cape or Lowveld sun can exceed the instrument's operating range. The Leeb500 is rated −20 to 70 °C and the Uee981E −10 to 50 °C. Shade the instrument, use a couplant suited to hot surfaces, and re-check calibration as the part cools.
Calibration blocks and couplant
Verify every instrument and probe on a reference block before each job, and record the DAC or TCG settings. Ecotao can supply calibration blocks, spare probes, cables and couplant with your instrument.
Need wall thickness rather than flaw detection? See our Leeb ultrasonic thickness gauges.
Standard probes and optional accessories
← Scroll to see full table →
| Item | Specification | Use |
|---|---|---|
| Straight probe (standard) | 2.5 MHz, Φ20 mm, Q9-Q9 cable | Laminations, forgings, castings, thickness checks |
| Angle probe (standard) | 4 MHz, 60°, 8×9 mm crystal, Q9-C5 cable | Butt and fillet weld inspection |
| Optional probes | Other frequencies, angles and dual-crystal probes | Thin sections, near-surface flaws, coarse-grained materials |
| Calibration blocks | Ask Ecotao for the block your procedure specifies | Instrument and probe verification, DAC/TCG set-up |
| Cables and couplant | Spare probe cables and coupling agent | Replacement and consumables |
The standard probe set above is supplied with the Leeb500, Leeb510 series and Uee952/953.
Frequently asked questions about ultrasonic flaw detectors
What is an ultrasonic flaw detector and how does it work?
An ultrasonic flaw detector is a portable non-destructive testing (NDT) instrument that sends short pulses of high-frequency sound (typically 0.5 to 20 MHz) into a solid part through a probe. Sound reflects from the back wall and from any internal discontinuity such as a crack, void, slag inclusion or lack of fusion. The instrument times each echo and shows it on an A-scan display, so the operator can locate the flaw (depth, surface distance and sound-path distance) and estimate its size from the echo amplitude, without cutting or damaging the part.
What is the difference between the Leeb510, Leeb520, Leeb521 and Leeb522?
All four share the same 240 × 160 × 40 mm, 1.2 kg housing and the same standard probes. The Leeb510 and Leeb520 cover 0.5 to 15 MHz and 0 to 6000 mm; the Leeb521 and Leeb522 extend this to 0.5 to 20 MHz and 0 to 10 000 mm with better linearity and at least 65 dB sensitivity. The Leeb510 has 50 channels and 500 stored A-scans; the other three have 100 channels and 980 stored A-scans. TCG is on the Leeb521 and Leeb522 only, and B-scan and video recording are on the Leeb522 only.
What is the difference between DAC, TCG and AVG/DGS on a flaw detector?
All three compensate for the fact that the same size reflector gives a smaller echo the deeper it is. DAC (distance amplitude correction) draws a reference curve on screen from echoes of known reflectors at different depths, and the operator compares flaw echoes to that curve. TCG (time corrected gain) instead raises the gain with depth so that equal reflectors show equal screen height, which makes evaluation faster. AVG (also called DGS, distance gain size) uses probe-specific theoretical curves to express a flaw as an equivalent flat-bottom-hole diameter, which is common in forging inspection.
Which Leeb flaw detector should I choose for weld inspection?
For general structural and pipe weld inspection with an angle probe, any model with automatic DAC will do the job. If welds must be rated to AWS D1.1 or D1.5, choose the Uee981E or the Uee953, which have built-in AWS functions. For high-volume or audited work where you need TCG, B-scan imaging and video evidence, the Uee981E, Leeb522 and Uee953 are the strongest options.
Can an ultrasonic flaw detector measure wall thickness?
Yes. With a straight (0 degree) probe and a calibrated sound velocity, a flaw detector reads the back-wall echo to give thickness, and the A-scan also shows whether the reading is coming from the true back wall or from a lamination. For routine corrosion thickness surveys a dedicated ultrasonic thickness gauge is quicker and simpler to use. Ecotao supplies both.
Which probes come with a Leeb ultrasonic flaw detector?
The Leeb500, Leeb510 series and Uee952/953 are supplied with a 2.5 MHz, 20 mm diameter straight probe on a Q9-Q9 cable and a 4 MHz 60 degree angle probe (8 x 9 mm crystal) on a Q9-C5 cable. Other frequencies, angles, dual-crystal probes, cables, calibration blocks and couplant are available as options. Ask Ecotao for the probe set that suits your material and weld geometry.
Do ultrasonic testing operators in South Africa need to be certified?
For inspections that form part of a quality or statutory record, such as pressure equipment, structural steel or pipeline welds, clients and inspection authorities normally require the operator to hold an ultrasonic testing qualification under ISO 9712. In South Africa this certification is administered through SAQCC NDT. The flaw detector itself should be checked against EN 12668 / ISO 22232 characterisation requirements and verified on a calibration block before each job.
Does Ecotao deliver Leeb flaw detectors outside Cape Town?
Yes. Ecotao supplies Leeb ultrasonic flaw detectors from its Cape Town base to customers throughout South Africa and to Namibia, Botswana, Zimbabwe, Mozambique, Lesotho and Eswatini. Contact sales@ecotao.co.za or +27 21 911 5835 for lead times.
Talk to Ecotao about a Leeb flaw detector
Tell us the material, thickness and weld type you inspect and the standard you work to, and we'll recommend the right model and probe set. Supplied across South Africa and neighbouring countries.
- Head Office
+27 21 911 5835 - Zak
086 142 8716 - Zaid
082 390 3989 - Email
sales@ecotao.co.za
aqua@ecotao.co.za