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Multi-Unit Tensioners

Multi-Unit 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.

With a single tensioner for an application with many studs (or bolts), you still have to apply each bolt-load individually in a pattern that attempts to uniformly load the entire structure; like individually tightening lug nuts on an automotive wheel. 

For the ideal uniform loading of a system with many studs, there is nothing better than a system that applies the load to all studs at the same time. HTI makes a wide variety of multi-unit tensioning systems. 

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How Does a Multi-unit Tensioning System work?

The simplest multi-unit tensioning system is a large number of tensioners with dual hydraulic ports chained together with hydraulic hoses. Using hydraulic chaining, each tensioner will apply the load at the same time, at the same rate, and end up with the same applied load. This method is typically employed for large fastening jobs that are not done in high volume. 

All of the HTI standard fixed tensioners come with dual hydraulic ports and can be used in this fashion. Any of our custom-designed tensioners can also be used with chaining. 

Example of changing of individual tensioners

Example of chaning of individual tensioners

Multi-Unit Stud Tensioning systems

For uniform loading of tensioning jobs that are performed frequently, HTI designs tensioning systems with multiple tensioners attached to a fixture, for easy installation onto the studs. Here are a few examples of HTI tensioning systems. Keep in mind that HTI multi-unit tensioning solutions cover considerably more applications than shown here.

Flange tensioner

Flange tensioner

Flange tensioner

Flange Tensioners can be designed with single or multiple segments. A two-piece tensioner is easily installed around a pipe, while a tensioner for larger studs and flanges can be designed with multiple segments to reduce weight. Each segment has one or two ports depending on the hose connection configuration.

Cylinder head tensioners 

HTI makes multi-stud, cylinder head tensioning systems for large diesel engines, most notably for Wabtec (formerly GE) locomotives and for Cummins.  These units simultaneously tension all of the cylinder head studs and have gear-driven sockets to tighten the nuts once the studs are tensioned.


Locomotive head tensioning system

Locomotive head tensioning system

Steam generator handhold cover tensioning system

Steam generator handhold cover tensioning system

Steam generator handhole cover

This steam generator handhold cover is designed as a single unit as there are no obstructions on top of the cover to impede installation. Because all the load cells are in a single housing, the hydraulic coupling between load cells is internal to the housing, so the unit requires only a single hydraulic hose connection for operation.

Segmented chained tensioners

In some applications, a tensioning system can’t be put on as a single unit. HTI also makes custom tensioning systems that come in parts but work as a system.

Segmented ring tensioner for steam generator manway application

Segmented ring tensioner for steam generator manway application

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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.