Comparison between
Bolt Tensioners (SSV) and Hydraulic Nuts (HM)

  • Bolt Tensioners can be removed from the screw joint after achieving the desired pretensioning force. Hydraulic Nuts remain on the screw joint or assembly.

  • The pretensioning force, obtained in the screw joint by a Bolt Tensioner, is maintained by a mechanical element which is a nut in most cases. With a Hydraulic Nut (HM), however, the axial pretensioning force is maintained by the residual pressure in the hydraulic chamber or pressureless if the HM is equipped with a lock nut.

  • The Bolt Tensioner is removable and can pretension several screw joints one after the other, in contrary to the Hydraulic Nut remaining in place.

  • Since the Hydraulic Nuts remain in situ, compared with Bolt Tensioners they allow quicker change-over times at clamping / releasing and shorter finding of residual pretensioning force.
Video SSV

Video HM