Abstract: The invention concerns a method for making identity cores for ultrasound seals. Each core comprises a chip consisting of a brazed stack of metal disks 1 bearing at least one notch 3, the resulting identity being defined by the number, the size and the random angular position of the various notches in the stack and by the unpredictability of the brazing. The invention is characterized in that the notched disks 1 provided with a central hole 2 are first stacked in large numbers in a tubular metal sheath 4 with a circular cross-section corresponding to said disks 1. The stack is then axially compressed in the sheath 4 and a brazing bead 7 is inserted in the channel constituted by the assembly of aligned central holes 2. After brazing in a vacuum oven, the two ends of the sheath are eliminated and the resulting column is segmented perpendicularly to its axis into a series of individual identity chips 8 of predetermined thickness.

Abstract: A sealing fastener includes a unique identifier device for the individual fastener that enables ultrasonic identification of the device using an ultrasonic fault measuring system, and a frangible element within the fastener integrated with the identifier device that provides an ultrasonic signature indicating an attempt to loosen or remove the fastener when subjected to an ultrasonic signal generated by an ultrasonic fault measuring system. The unique identifier device includes a stack of individual metallic washer elements brazed together, with each washer element including discontinuities or cavities that are randomly arranged with respect to the cavities of the other washers in the stack. The fastener includes relatively movable portions that cause fracture of the frangible element upon any attempt to loosen or remove a fastener after it has been tightened or secured at its sealing location.