Radiator

A radiator comprising mutually parallel flat tubes connected to header pipes for the feed and return flow of the heating medium, said flat tubes having connection bores formed at a distance from each end of each said flat tube and on opposite sides at a distance from the longitudinal axis of the tube, and said flat tubes having inside support parts resting against the mutually opposite inner tube walls in the region of the connection bores, the improvement wherein each said support part is angled into a U-shape of approximately the same width as the internal width of the tube, said support part having two bent ends each of which being formed for coaxially surrounding a portion of the circumference of one of the connection bores, said support part also forming the end closure wall of the flat tube and being welded thereto along the end edge of the tube, the header pipes having connection bores in alignment with the flat tube connection bores, connecting rings provided for connecting the flat tubes and header pipes together, the connecting rings having tapered end faces for applying pressure welding and being disposed in alignment with the aligned connection bores coaxially with each bent end of the U-shaped support part for connecting by pressure welding the flat tubes to the header pipes.