A process of manufacturing sealed packages containing a pourable food product from a web packaging material moving along a predetermined path involves providing a recurring pattern of printed register marks on the web packaging material, applying a recurring pattern of bend or fold lines on the web packaging material as a function of the detected position of the printed register marks, generating new references, distinct from the bend or fold lines, on the web packaging material in a synchronized way with the application of the recurring pattern of bend or fold lines; and performing one or more subsequent operations on the web packaging material based on a synchronization pulse created by detection of the new references.