Traditional manufacturing processes for large diameter pipe can result in reduced collapse pressure compared to seamless alternatives. However this can be avoided by finishing longitudinally welded pipe by compression rather than expansion, which can improve the performance over seamless pipe.
A unique cold sizing press called Impander® has been developed by Eisenbau Krämer to produce pipe with reduced ovality, reduced residual stresses and increased compressive yield strength to significantly increases collapse pressure.
Pipes larger than 16 inches in diameter are mainly produced by cold forming using the UOE or JCO processes. After the seam is welded, the pipe is finished by expansion or outside calibration, but its collapse pressure can be up to 30 percent lower than that of seamless pipe with the same diameter, thickness and steel grade.
Pipe with diameters ranging from 14 to 60 inches can be compressed to a pre-chosen value that can exceed 1.0%. This calibration and compression process produces pipes with internal diameter tolerances of less than 0.5 mm and ovalities smaller than 0.5% over the whole length of the pipe.