A Device for measuring a force applied by a fitting apparatus provided with a threaded rod having an external or internal thread, includes a hydraulic chamber containing a fluid; a piston configured to slide inside the hydraulic chamber; a threaded connector fixed to the piston, the threaded connector having a thread configured in such a way that the threaded rod screws onto the threaded connector, so that the threaded rod can impose an axial force on the piston resulting in travel of the piston in the hydraulic chamber; and a pressure gauge communicating with the hydraulic chamber, configured to measure a pressure inside the hydraulic chamber created by the axial force applied on the piston by the threaded rod.