HSAW large tubes can be produced from steel strip as spiral tubes. In this process, the coiled strip is continuously unrolled, helically shaped and welded. The helical weld seam requires a particularly accurate guidance of the probes. The automatic, laser-supported seam detection ensures that the probes are guided exactly centrically with respect of the weld seam (seam tracking).
Longitudinal and transverse flaws are detected with an angle beam insonification into the spiral seam, with the transverse flaw detection probes coupled directly to the seam by means of a water jet. Vertical probes are used to check the heat-affected zone next to the weld seam for laminations.
Usually, tube mills use two weld seam inspection systems: The first system inspects the continuous tubing directly after welding and works as a process control. The second system is used for final inspection of the finished tube.
- Inspection of helically submerged arc welded (HSAW) tubes
- Typical tube diameters are 300 mm to 3600 mm
- Usually two weld seam inspection systems: First inspection on the continuous tubing and final inspection on the finished tube
- Longitudinal and transverse flaw inspection with angle-beam insonification, lamination inspection in the heat-affected zone with straight-beam insonification
- Optional lamination test on the tube and tube body (if no pre-tested strips are used)
- Laser-based tracking of the weld seam for optimal positioning of the probes