An apparatus for longitudinally welding and severing superposed thermoplastic films forming a packaging hose includes first and second feed rollers each having an outer periphery contacting one another for advancing the films passing therebetween; a drive for rotating at least one of the feed rollers; a circular heating disk mounted in the first feed roller coaxially therewith and having an outer diameter greater than the peripheral diameter of the first feed roller; and a circumferential groove provided in the second feed roller in alignment with the heating disk. Peripheral portions of the heating disk project into the circumferential groove of the second feed roller.