A manifold, especially a supply or receiving tank in a heat exchanger, is provided as an extruded/drawn tube with an outwardly and longitudinally extending protrusion part. Fastening flanges with a size larger than the width of the protrusion part are an integral portion of the protrusion part. The shaped tube with protrusion part is extruded or drawn, and then the protrusion part is perforated to form a plurality of apertures which are transformed in one or more steps by cold deformation into the fastening flanges of desired diameter, shape and length.