LGE Engineering — Industrial Measurement Systems
3DShaper · post-weld inspection · tube & pipe

Automated post-weld inspection
for tube & pipe production lines

Inline weld-seam evaluation, defect detection, full 360° coverage, straightness and ovality measurement — integrated directly into your tube or pipe mill for real-time quality control.

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Weld seam & defect detection

External weld geometry, undercut, overlap, bead irregularities — reliable detection at production speed.

How does the system detect external weld defects such as undercut, overlap and bead irregularities?

The system uses a dedicated 5th sensor head optimised for the weld-seam region. It acquires high-resolution 3D profiles of the weld bead and surrounding area, allowing real-time evaluation of:

  • Bead height and width
  • Undercut (excessively deep groove at the weld toe)
  • Overlap (excess weld metal extending over the base material)
  • Lack-of-fusion or incomplete-penetration indicators
  • Surface porosity and irregularities

All measurements are compared against user-defined tolerances, and defective sections are flagged immediately.

The 5th head ensures a clear, unobstructed view of the weld seam even at high line speeds, enabling reliable detection of critical weld defects.

What is the minimum detectable defect size at 50 m/min line speed?

Detection capability depends on both the spatial resolution and the acquisition rate. At 50 m/min (833 mm/s) with a 16 kHz profile rate, the longitudinal sampling step is approximately 52 µm. Reliable detection requires averaging at least three profiles, so the minimum detectable defect length is about 150 µm.

For width, the sensor provides 3200 points per profile; lateral resolution is between 56 µm and 75 µm, depending on the standoff distance.

Min. defect length: ~150 µm Lateral resolution: 56–75 µm Profile rate: 16,000 profiles/s

These figures represent worst-case conditions (maximum speed, extreme product size). At lower speeds or more favourable geometry, even smaller defects can be detected.

Full 360° coverage & geometry

Round and rectangular profiles, ovality, straightness and corner radius — all in one pass.

Can the system inspect both round and rectangular tubes or pipes with the same configuration?

Yes. The 3DShaper platform with static heads covers round pipes from OD 168.3 mm to 339 mm and square or rectangular profiles from 140×140 mm up to 200×300 mm. The multi-head arrangement provides full 360° coverage for both geometries.

For rectangular profiles, corner radii and flatness are automatically evaluated; for round pipes, ovality and diameter are measured at multiple cross-sections along the length.

How is straightness measured, and what accuracy can be expected?

Straightness is derived by computing the centroid of each measured cross-section along the tube or pipe axis. Deviations from a perfectly straight line are then calculated. The system can average multiple sections to improve accuracy.

Typical straightness accuracy is within ±0.15 mm over 1 metre, depending on the number of averaged sections and the total measured length.

Straightness measurement is fully integrated with dimensional and weld inspection, providing a complete quality picture in a single pass.

Accuracy, repeatability & operating conditions

Guaranteed sensor specifications and environmental robustness for harsh production environments.

What are the guaranteed accuracy and repeatability specifications?

Each sensor provides the following baseline specifications:

Repeatability: 10 µm Linearity: ±0.035% of full scale Profile interval: 75 µm default, down to 50 µm Points per profile: 3200

Overall system accuracy, taking into account real-world factors (temperature drift, mounting, etc.), is typically ±0.100 mm for the 380 series in the worst-case range. For weld inspection, the dedicated head achieves similar performance, ensuring reliable defect detection.

Is the system suitable for product temperatures up to 80 °C?

Yes, with active cooling. The sensor frame is equipped with Peltier-based thermoelectric air conditioning to maintain a stable internal temperature. This is essential not only for hot products but also for cold ones, as it minimises temperature drift and thermal expansion of the frame.

The Peltier system has no moving parts and no direct air exchange, keeping dust and dirt out. For applications with sudden temperature changes greater than 10 °C, carbon-fibre plates can be used to further reduce thermal expansion effects.

For product temperatures up to 80 °C, the standard Peltier cooling is sufficient. For higher temperatures, additional measures may be required — please consult our engineers.

The product surface may contain process oil. What surface condition is required for reliable measurement?

The surface should be free from oil drops and excessive contamination. Oil droplets are interpreted by the system as part of the pipe or profile, leading to measurement errors.

An air-wiping or air-spray system installed upstream of the measurement station is strongly recommended. Some users prefer alternative methods (e.g. mechanical wiping), but air spray is the most effective and maintenance-friendly solution.

All vision- and laser-based systems are subject to this limitation. X-ray, UT and eddy-current methods are immune but offer far lower resolution and are not suitable for full-profile inspection.

Ready to inspect your welds inline?

Send us your tube sizes, weld types, line speeds and quality standards — our engineers will recommend the optimal 3DShaper configuration.

Request a live demo or feasibility study