Heavy pressure vessel procuction automation requires rigid roller beds and large size welding Column and Booms or welding platforms, which carries several welding heads.
The narrow gap SAW technique is used on workpieces for which the plate wall is exceptionally thick, typically 50-350 mm. Workpieces such as this are usually needed, for example, in large pressure vessels and other components used in the energy, offshore and chemicals industries.
A deep yet narrow gap provides outstanding strength, thanks to the low heat input. A narrow, preformed welding gap also reduces the gap volume and decreases the amount of fillet material needed.
On the other hand, producing a quality seam is a process that places extraordinary demands on a production facility. PEMA’s 100-1200-ton roller beds are designed to meet the special needs of narrow gap welding. In narrow gap welding, the workpiece must be rotated with extreme precision, with no axial movement, even over the longest period of time. For this reason, PEMA’s large roller beds come equipped with an automatic hydraulic anti-creep function that adjusts the rollers to work against the movement of the workpiece to prevent axial movement. Normally, welding gaps must be heated to temperatures of several hundred degrees, but this is also taken into account in PEMA’s large roller beds.
Welding process productivity can be significantly improved by using a tandem narrow gap process, in which two wires are used simultaneously.