PRODUCTION METHOD OF LONGITUDINALLY WELDED MAIN PIPES Russian patent published in 2014 - IPC B21C37/06 

FIELD: metallurgy.

SUBSTANCE: method involves production of a pipe from a sheet workpiece with preliminary bending of longitudinal edges and further U-shaped or O-shaped deformation of the above workpiece, as well as welding of process planks in the zone of longitudinal side edges of the sheet workpiece, which are connected by welding, processing of edges of the above ends and their welding so that a longitudinal connection weld of pipes is formed. Process planks for each sheet workpiece are made of process cut-off pieces obtained at production of sheet workpieces of the same melt as the workpiece. Cut-off pieces with the thickness corresponding to thickness of that workpiece are used, and welding of planks to end faces of the sheet workpiece and processing of longitudinal edges of that workpiece is performed before its shaping, thus performing a welding process so that a gap between adjacent planks does not exceed 6 mm after connection of ends of the workpiece before welding of a longitudinal weld of the pipe. After that, welding of process as well as internal and external connection welds is performed in series. Adjustment of a welding tool and parameters of the process is performed on process planks with change-over to a stable welding mode immediately in the connection zone of ends of a pipe workpiece.

EFFECT: stable welding process throughout a longitudinal connection weld and improved quality of ready-made main pipes.

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