Abstract: A method of making a brazeable metal pipe which has elliptical tube-insertion apertures and guide lugs extending from at least one of the opposite edges defining the minor axis of each aperture, with the guide lugs extending in the direction of insertion of flat tubes. The method in an embodiment comprises the steps of: bending a part of a raw strip, which may be previously embossed to form recesses, so as to provide a bulged portion arc-shaped in cross section and connected to at least one unbulged flat portions; pressing inwardly to form inward swells; subsequently punching each inward swell to provide the tube-insertion aperture so that at least one of the opposite edges located at ends of the minor axis of said aperture remains unpunched; and finally bending the at least one unbulged portions to produce the finished pipe.

Abstract: A heat exchanger includes a core and a pair of headers, the core including flat tubes and corrugated fins sandwiched between the tubes, the headers having holes in which the end portions of the tubes are inserted, wherein each tube comprises a stop means for ensuring that an adequate length of the tubes become inserted in the headers.

Abstract: A process for producing brazeable pipes particularly for use in heat exchangers, the process comprising preparing a brazing sheet which comprises a core sheet coated with a brazing substance at least on one surface, forming a bulged portion of a semi-circular cross-section in the central section of the brazing sheet, providing apertures in the bulged portion for securing tube ends therein, and rolling the brazing sheet into a cylinder with its opposite ends being butt jointed to each other.