Method for carrying out ventilation in a multi-walled container

A method for carrying out ventilation in a multi-walled container of the type comprising a rigid external housing, inside which a flexible inner pocket for containing a product is arranged and connected to a withdrawal device without ventilation, the layers having no adhesion between the same such as to be able to be separated without difficulty and with air ventilation between the same, characterized in being obtained by means of molding a projection at the upper or lower part of the pre-form which is subjected to a first operation of cutting a sprue, then a second operation of cutting the projection in a region close to the base and/or the neck of the recipient for production and a third operation of separating the layers.