SAW pipes have to be calibrated after forming and welding, so that the required ovality and straightness tolerances are achieved. For certain areas of application, the conventional calibration procedure is, however, not sufficient. Therefore, EEW introduced two important technical innovations.
The use of specially designed plate edge crimping presses guarantees the perfect pipe shape along the logitudinal weld seam. The danger of peaking or flattening next to the weld seam is thereby eliminated. Additionally, this method lowers the risk of squeezing or pinched edges and induces much lower residual stresses.
The modified calibration method makes the production of pipes with very close tolerances possible and simultaneously leads to a significant reduction of residual stresses. This takes place by compressing the pipes many times using a uniaxial 35 MN calibration press with specially designed tools.