METHOD FOR THE PRODUCTION OF LONGITUDINALLY WELDED PIPES OF LARGE DIAMETER FROM LOW ALLOY STEEL Russian patent published in 2023 - IPC B21C37/08 

FIELD: pipelines.

SUBSTANCE: method for production of large-diameter straight-seam pipes from low-alloy steel includes milling longitudinal edges, bending them, moulding strip products into a pipe billet, its welding and subsequent expansion. After milling the longitudinal edges, the ratio of the lower chamfer to the upper chamfer is no more than 1.45, the blunting angle is no more than 9°. The height of the bending of the strip edges before forming is: Y"=(1.5-3.5)×S, where Y” – bending height, mm, S – nominal pipe wall thickness, mm. After moulding, the angles of the X-shaped cutting of the edges are at least 60°. Welding of the inner seam of the pipe billet is carried out with a heat input of 30.0-50.0 kJ/cm, and welding of the outer seam is carried out with a heat input of 32-52 kJ/cm.

EFFECT: construction and safe operation of a pipeline with an outer diameter of up to 1420 mm and a working pressure of up to 14.71 MPa is ensured.

7 cl, 2 dwg, 3 tbl