Abstract: The present invention provides a device and method for installing sensor/transductor elements on the inside wall of tubular structures, comprising a step of cleaning the inside of a duct and a step of installing the sensor/transductor. The mechanical device that is the subject matter of the present invention comprises four articulated arms (2), each one being coupled at the ends thereof to through-slits (23) in prismatic components (21) and the latter coupled to control elements (1) and (31) which by means of the threaded axial through-holes (24) thereof are screwed to the power screw axes (30) and (32) and by actuating same by rotating the extension tube (5) cause radial movement of the articulated arms (2), said retractable mechanical device also comprising centralizing elements (34) composed of at least 4 spring shafts (35).