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Tightening with Hydraulic Bolt Tensioners

Tightening with Hydraulic Bolt TensionersWhile many of our blog posts focus on torque wrenches, it’s important to recognize some of the other members in the bolt tightening family.

Today we’ll look at one of those tools: hydraulic bolt tensioners.

For this tool to do its job, you’ll need to begin with a bolt that has an end that protrudes above the tightening nut. An annular hydraulic cylinder is then placed around the bolt, applying cold extension. The bolt undergoes an axial traction load, while the nut is turned down with little effort, without transmitting torque to the bolt.

When the tensioner releases its fluid pressure, the majority of the hydraulic load on the tensioner is transferred to the nut and the tightening is complete.

Hydraulic bolt tensioning comes with a number of benefits:

  • They’re very accurate. With a hydraulic bolt tensioner, traction load is controlled by the hydraulic pressure in the tensioner, allowing for more accuracy. The load isn’t dependent on the friction efficiencies of the assembly.
  • There’s no damage to components when using hydraulic bolt tensioners. They control internal stresses, and generate no friction under heavy bearing pressure. This method therefore protects each component of the assembly.
  • Hydraulic bolt tensioning is easy to perform and requires no physical exertion, even with very large bolts. This means a safer workplace and happier workforce.
  • With hydraulic bolt tensioning, you are able to eliminate torsion stress in the bolt.
  • Hydraulic tensioning works with a range of materials, such as stainless steel, composite materials, titanium and others. It’s also a method that works on a wide variety of bolt diameters.
  • In addition to tightening, hydraulic bolt tensioners also make it easy to untighten bolts. The hydraulic effort required is typically around one percent greater than the effort needed for the previous tightening phase.

As we said above, hydraulic bolt tensioners are very accurate, but in the world of fasteners, it’s crucial to be certain about your tools.

That’s why Maxpro recommends its bolt tension calibrator, used to certify all bolts, tensioners, hydraulic wrenches and other multipliers.

Among its features:

  • Three-position reaction bar
  • Solid, heavy-duty gauge protector
  • Gauge reads in Lbs. or Kilonewtons
  • “Snap-In” front plate and back bushing
  • A325, A490 and B7 bolt spec label
  • Accessories include test bolts, spacers, rear hex sockets and extended reaction bar

For more information about this product or any of our other torque tools, contact Maxpro today.

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