Abstract: Two thin-walled jackets a joined by preparing end faces of the jackets by plastically deforming and upsetting microprojections thereon and thereby forming the metal of the upset microprojections into annular beads on inner surfaces of the respective jackets. Then the end faces are abutted while centering the jackets on each other relative to their external diameters. The end faces are then spot welded together in a plane where the end faces abut and then joined with a continuous main weld having a width equal to between four and six times the thickness of the wall of the jackets. Heat is then extracted from the welded jackets starting at a distance not exceeding times the wall thickness from a joint center line where the end faces abut.