CIRCUMFERENTIAL WELDING JOINT OF MAIN PIPE, METHOD FOR FABRICATION OF CIRCUMFERENTIAL WELDING JOINT OF MAIN PIPE AND MAIN PIPE Russian patent published in 2017 - IPC B23K9/28 B23K9/18 B23K9/23 

FIELD: technological processes.

SUBSTANCE: group of inventions relates to a circumferential welding, a process for its fabrication and to a main pipe. End parts of steel pipes with the yield strength according to API 5L specification not lower than 555 N / mm² are joined together. The joined parts are welded together in circumferential direction. This welding is performed using the welded materials and under welding conditions selected from the provision of ensuring the critical equivalent plastic strain ε_p-cri (%) of formation of viscous crack in the heat-affected zone of the base material, conforming to the formula σ_match>4,85ε_p-cri^-0,31, where σ_match - welding strength ratio which is determined according to the expression: σ_match=(TS-w/TS-b)⋅(YS-w/YS-b), where TS-w - tensile strength of the weld metal , TS-b - tensile strength of the base material, YS-w - yield strength of the weld metal, YS-b - yield strength of the base material, while the relation YS-w/YS-b≥1,0 is fair.

EFFECT: document describes the process of circular welded joints, as well as the use of this method of connection to the main pipe.

5 cl, 1 dwg, 1 tbl, 7 ex