A machine for welding a plastic spout to a plastic package, the plastic package comprising two film walls with an inner surface, an outer face, and a film welding interface having a material with a known first melting temperature, and the plastic spout having a neck portion with a pour channel having a longitudinal central axis, and at least one welding interface portion made of a material with a known second melting temperature, the welding interface being connected by means of welding between said two film walls of the plastic package, characterized in that the machine comprises: - a heating station integrating at least two hot air supply nozzles directly facing one another and separated by a given distance, said hot air supply nozzles being connected to hot air supply conduits; - a unitary dispenser device for dispensing plastic spouts, configured for collecting a plastic spout from a storage unit and positioning it in said heating station by means of a delivery element, held at least at its welding interface portion, with its pour channel with a longitudinal central axis in a vertical position and with the neck downwards, the welding interface portion being located between said two hot air supply nozzles; - a welding station comprising at least two welding jaws arranged directly opposite and separated from one another, between which there is arranged a mouth section of a plastic package of a plurality of plastic packages which are fed, in an aligned manner, by a conveyance line to said welding station, which provides pressure and a temperature close to said known first melting temperature to said mouth section; - a gripping device configured for temporarily gripping the neck portion of the plastic spout in said heating station and rapidly transferring the plastic spout to the welding station, by means of a positioning rotation, turning said plastic spout over and placing the welding interface portion of the plastic spout, once it has been heated, inside the open mouth section of a plastic package of said plurality of plastic packages; and - at least one control unit managing, in a coordinated manner, the operation of said heating station, the dispenser device for dispensing plastic spouts, the delivery element for delivering the plastic spout, the gripping device, and the welding station, such that when the gripping device grips the neck portion of the plastic spout, this spout is released from the hold of the delivery element, wherein said gripping device comprises two clamps assembled at the end of a motor-driven rotary shaft, such that a rotation of the shaft determines said quick transfer and turning over of the plastic spout, with the welding interface portion of the plastic spout going from said heating station to being located between the two film walls demarcating the open mouth section of a plastic package in the welding station. - a heating station integrating at least two hot air supply nozzles directly facing one another and separated by a given distance, said hot air supply nozzles being connected to hot air supply conduits; - a unitary dispenser device for dispensing plastic spouts, configured for collecting a plastic spout from a storage unit and positioning it in said heating station by means of a delivery element, held at least at its welding interface portion, with its pour channel with a longitudinal central axis in a vertical position and with the neck downwards, the welding interface portion being located between said two hot air supply nozzles; - a welding station comprising at least two welding jaws arranged directly opposite and separated from one another, between which there is arranged a mouth section of a plastic package of a plurality of plastic packages which are fed, in an aligned manner, by a conveyance line to said welding station, which provides pressure and a temperature close to said known first melting temperature to said mouth section; - a gripping device configured for temporarily gripping the neck portion of the plastic spout in said heating station and rapidly transferring the plastic spout to the welding station, by means of a positioning rotation, turning said plastic spout over and placing the welding interface portion of the plastic spout, once it has been heated, inside the open mouth section of a plastic package of said plurality of plastic packages; and - at least one control unit managing, in a coordinated manner, the operation of said heating station, the dispenser device for dispensing plastic spouts, the delivery element for delivering the plastic spout, the gripping device, and the welding station, such that when the gripping device grips the neck portion of the plastic spout, this spout is released from the hold of the delivery element, wherein said gripping device comprises two clamps assembled at the end of a motor-driven rotary shaft, such that a rotation of the shaft determines said quick transfer and turning over of the plastic spout, with the welding interface portion of the plastic spout going from said heating station to being located between the two film walls demarcating the open mouth section of a plastic package in the welding station.