What is bolt tensioning?
The efficient way to tighten bolts
Product design engineers specify bolting as being able to develop a specific compressive load that holds joints together. This load is divided across a number of fasteners which must be stretched elastically to provide the correct spring return force collectively.
Torque tightening by screwing the nut onto a bolt thread is the most common method, but has limitations of accuracy as there are massive reactive forces generated by surface friction in threads and between the nut and the joint face.
Hydraulic bolt tensioning is a quicker, easier, and safer way to tighten large bolts to their optimal specified tension. It eliminates the need for torque and for forceful, manual tightening. As the operator can preload the exact required tension of the bolt via the amount of hydraulic pressure exerted, it offers consistent accuracy.
How does it work?
There are a number of different tooling designs using the basic hydraulic “direct tensioning” principle. Depending upon the application needs, these can take the form of:
- The hydraulic nut — where the item remains in place.
- A bolt tensioner — which applies the tensioning force but is subsequently removed from the job.
- Any number of tailored solutions including Technofast’s high temperature products, such as EziTite TR Hydraulic Nuts or CamNut Systems.
In all of the products, the hydraulic pressure is produced externally by standard pumping equipment and directed to create the ideal force specified to load the subject bolt to its ideal tension.
By using the Direct Tension method, operators can avoid over-tensioning bolts, avoid galling of threaded fasteners, and avoid the need for rework whilst improving the efficiency of the operation and offering much improved safety for operators.
For EziJac Bolt Tensioners, the operation is similar. The Bolt Tensioner is built as a tool of modular components and is removed from the job after the tensioning operation is complete.
Install the tool onto the bolt
First, install the EziJac bolt tensioner or EziTite nut onto the bolt and connect the hose.
Activate the Pump
Activate the pump so that hydraulic oil flows into the load cell.Load Generated
The load is generated within the sealed internal surface area of the tool or hydraulic nut and the force is transferred directly to the subject bolt. Lock The Nut
The nut rotator/lockring can then be engaged to mechanically lock the load onto the bolt.Release The Pressure
What are the benefits of using a Direct Tension hydraulic method?
It’s Safer
Eliminate physical exertion and keep your operators safe — they no longer need to use hammer tightening methods or hold torque tools in place during operation.
It’s Efficient
Eliminate physical exertion and keep your operators safe — they no longer need to use hammer tightening methods or hold torque tools in place during operation.
Less Physical Exertion
Technofast products use hydraulic pumps to generate bolt force, eliminating the need for physical labour and manual tightening. This thereby requires less physical exertion from your team and creates greater safety for your workers on-site. These products can prevent exertion-related injuries.
Better Accuracy
These products remove the need for repeated ‘star pattern’ tightening cycles needed for torque tensioning tools. Ideally, all bolts are tightened simultaneously from one pressure source. This allows a perfect balance of force across all bolts in the joint so that no bolt carries more or less load than others in the pattern.
Innovation solutions for your industry.
Technofast Industries is an worldwide leader and specialist in Bolt Tensioning, providing innovative and effective technical solutions along with uncomprising customer service.
