The objective of any tightening operation is to achieve the correct and uniform clamping force in the joint.
When using hydraulic bolt tensioners, the bolt tension (or preload) is known through the hydraulic pressure applied, the residual bolt load at the end of the tightening cycle is subject to the amount of relaxation which occurs on the load transfer. The residual bolt load then depends on several factors, some are joint related, some are tool related and some are operator related. For example:

  • Tolerances in bolt, nut and flange gasket material
  • Tolerances in bolt, nut and flange gasket material dimensions
  • Operator skill and control of the operation
  • Load loss during the process
  • Calibration of pressure gauges
  • Correctly maintained equipment

If you have any questions about the operation of Hydraulic Bolt Tensioners or you would like to discuss any of the topics in this entry please contact David Shaw at david@winshawllc.com or 832-540-3831
(Guidelines for the Management of Bolted Joints for Pressurized Systems, 2007)