Abstract: An internal centering device which is particularly suitable for the connection of tube ends wherein there are fitted onto a central supporting member of mainly axial development two hollow mandrels of which at least one is adapted for axial movement and at least one is articulated on the said central body and is provided with at least three radial actuators which are disposed sufficiently remotely from the corresponding articulation, for angular positioning of the mandrel in relation to the said central body, each mandrel having an outer elastic sleeve which is capable of being radially expanded by an internal hydraulic axial actuator having two opposing threads. Also described are particular types of axial actuators as well as alternative embodiments.