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Through-Hole

Through-Hole Stud Tensioners

Hydraulic tensioning is the ideal method for tightening bolted connections. Hydraulic tensioning eliminates inaccuracies and helps achieve correct bolt loading in critical connections. At HTI, we’ve been building hydraulic tensioners and nuts since 1986.

Through-hole (also called hollow-piston or hollow-plunger) tensioners are intended for use with long protruding studs, such as for wind turbine foundation bolts, or with a proprietary rolled threaded rod. Rather than the puller screwing onto the stud, as with a normal tensioner design, a through-hole tensioner uses standard stud nut threaded onto the protruding threads on top of the puller as the reaction nut, to transfer the load from the tensioner to the stud.

Like all HTI tensioners, HTI’s through-hole tensioners are simple to operate and maintain, designed and built using Total Quality Assurance, and provide extremely dependable operation.

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Through-hole tensioner showing separate reaction nut at the top

Through-hole tensioner showing separate reaction nut at the top

Wind turbine foundation through-hole tensioners

Wind turbine foundation through-hole tensioners

HTI hollow piston tensioner features:

  • Trouble-free, No–Leak, Lo–Friction Seals
  • Overstroke Indicator
  • Extra–Long Working Stroke (0.6 inch/15mm)
  • Compact and Lightweight Design
  • Single or twin hydraulic ports
  • Available in a variety of finishes
  • Standard (manual) return or spring return

How to operate a through-hole stud tensioner

The operator places the Bridge and Nut Rotating Socket over the nut and places the Load Cell Housing over the stud. They then thread the customer-provided load nut on top of the load cell. They then connect the through-hole tensioner to the Hydraulic Pump via Hydraulic Hoses with Quick-Disconnect (QD) fittings.

The Hydraulic Pump supplies high-pressure hydraulic oil to the Tensioner Load Cell, producing an accurate axial tension that stretches the stud. When the pump reaches a pre-set pressure, the operator uses a small bar to tighten the nut by hand.

The operator then removes the load nut, and then the load cell and bridge, and the process is complete.

Custom Engineered Tensioners Since 1986

HTI has been designing engineered solutions to your toughest bolt tensioning problems since 1986! You can choose from one of our standard catalog sizes above, or we can design a custom fixed tensioner for any application when a standard model won’t work. HTI tensioners can be designed for imperial or metric-sized studs, high loads, high temperatures, large stud sizes, or corrosive environments. Our multi-unit tensioning systems can make easy work of large bolted systems, and our automated tensioning systems can reduce labor and increase throughput in high-volume manufacturing applications. 

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If you have questions, comments, would like more information about our products, or want to get started designing your custom tensioning solution, please contact us and we will respond promptly.