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Rotabolt 1 – the original

The reliability of a bolted joint depends on three factors: the joint construction, the quality of the bolts and the load tension at assembly. Rotabolt ensures the quality of the bolt and the required load tension at installation because each bolt is individually load tested at conversion.

Rotabolt uses normal bolts that are converted through the mounting of a load tension indicator consisting of a metal pin, a rotor and a protective capsule filled with lubricant. The metal pin (measuring pin) is made from a material with the same thermal expansion coefficient as the bolt. A RotaBolt installation works just as well at low as at high temperatures. During the conversion a hole is drilled in on end of the bolt. At the bottom of this hole the metal pin with the rotor is fitted.

Before the bolt is mounted (and loaded) the rotor turns freely. When the screw is mounted the load tension increases in pace with the screw “extending”. The distance (gap) between the rotor and the screw, reduces until the gap disappears and it is no longer possible to turn the rotor. The required load tension has then been reached.

If the load tension reduces during operation a new gap is formed and the rotor can be turned, which indicates that the required load tension has disappeared.