The gas manifold (1) adapted for installation on a cooking range includes a conduit (2) for distribution of a flow (Q) at a pressure “P”, with a number of regulating taps (5) fixed to the conduit (2). The conduit is made from a metal pipe (3) with a thin cylindrical wall To and the pipe end (6) is sealed without cracks by means of friction welding with no addition of material, with a sealing wall (7) formed by means of a thickening in the form of a tip (7a) in the axial direction of an enlargement or height “H” greater than the original thickness To of the pipe. For making the gastight closure a rotary tool (8) is used that includes at least two rotary rollers (9) for the compaction of the metallic mass between two counterposed centripetal forces (Fr), in combination with an axial stretching force (Fa).