WELDED STEEL LARGE-DIAMETER PIPE PRODUCED BY UOE PROCESS AND ITS STRUCTURE Russian patent published in 2016 - IPC B21C37/08 

FIELD: metallurgy.

SUBSTANCE: steel pipe is shaped at U- and O-like bending presses for pipe expansion with the help of dies in UOE process. The pipe outer surface is wavy in lengthwise direction. The pipe weld rupture at bending is prevented by making the pipe has no local minimum of wavy diameter in the length range of 2.26λ to 3.86λ from both end sections in lengthwise direction. Or the pipe has flat sections whereat variation in the pipe diameter is smaller than or equals 0.02 percent of the steel UOE pipe OD. Said flat sections are located in at least the range of 2λ from both end sections in lengthwise direction where λ is defined by the mathematical relationship.

EFFECT: perfected process.

5 cl, 9 dwg