Patent ID: 7012217

Claim:
A method of making a welded large pipe from hot strip of steel, comprising the steps of: a) unwinding a hot strip; b) connecting a leading end of the strip with a trailing end of a leader strip; c) two-stage leveling of the hot strip for strip flatness in transverse direction; d) leveling the hot strip for strip flatness in longitudinal direction; e) ultrasonic inspection of an entire surface of the hot strip including inspecting strip edges of the hot strip; f) four-stage preparation of the strip edges; g) bending the strip edges; h) shaping the hot strip into a slotted tube; i) welding the strip edges along the inside and outside of the slotted tube by laser to thereby form a pipe; j) online process diagnostic of the welding step; k) online measurement of a pipe diameter; l) online determination of a profile of the welded seam; m) computer tomographic determination and evaluation of flaws inside the pipe; and n) ultrasonic inspection of the welded seam.