The invention relates to an installation and a method for producing infusion bags having a means of access and an injection stopper. The invention also relates to such a bag and various injection stoppers. In the system according to the prior art, a piece of flexible tube is welded into a bag, the port being plugged onto said piece of flexible tube. The port is not additionally fixed but is held in the flexible tube purely by way of tension. As a result, sealing problems can theoretically occur. By contrast, in the novel system proposed here, the port is welded directly into the bag. The flexible tube is thus dispensed with as an intermediate piece. This results in particular in the advantage that, for each bag, over 30 mm of flexible tube are saved, this not only making the installation construction more favourable but also doing away with the flexible tubes with their relatively high costs. Furthermore, the flexible tube and the port can optionally be welded in using the same welding tool. The operator of the installation can decide whether to weld in one flexible tube and one port or two flexible tubes. It is not necessary to change tools for this purpose. If the operator of the installation welds in two flexible tubes, the standard ports according to the prior art can still be placed on the flexible tubes.La presente invención se relaciona con una instalación y con un método para la producción de bolsas de infusión teniendo un acceso y un tapón de inyección. La invención se relaciona además con semejante bolsa y con diferentes tapones de inyección. En el sistema de conformidad con el estado de la técnica se suelda en una bolsa una pieza de manguera sobre la cual se inserta una puerta. La puerta no se fija adicionalmente, sino se retiene meramente por la presión de la manguera. Esto puede producir en teoría problemas de estanqueidad. En el nuevo sistema presentemente propuesto en cambio se suelda la puerta directamente en la bolsa. Así se omite la manguera como p
