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What is the difference between bolt torquing and bolt tensioning?
Bolt torque and bolt tensioning are both legitimate ways to seal a joint. Bolt torquing exerts a rotational force on the fastener, while bolt tensioning involves stretching a fastener with what looks like a hydraulic load cell.
What does bolt tensioning mean?
Bolt tensioning works by preloading the bolt, stretching it before the nut is tightened. The tensioner is clamped to the bolt’s threads and pushes against the flange in the surface being bolted. This provides a very consistent amount of stretch to the bolt, ensuring consistent bolt stretch and clamping force.
What is the purpose of bolt tightening?
Tightening the bolt puts the shank in tension, counteracted by compressive forces on the contact surfaces of the head and the nut, transferred from the parts.
What should bolts be torqued to?
US Recommended Bolt Torque
| Size | Recommended Torque | |
|---|---|---|
| Grade 2 | 18-8 S/S | |
| 5/8″ | 73 | 93 |
| 3/4″ | 125 | 128 |
| 7/8″ | 129 | 194 |
What is hydraulic tensioner?
A hydraulic tensioner system consists of a hydraulic actuator in combination with a tensioner pulley. High dynamic belt loads are controlled by hydraulic damping. This damping is created when engine loads force the piston rod to move inwards displacing the oil in the cylinder.
What is hydraulic tensioning?
A hydraulic bolt tensioning tool provides a quick and easy method for tightening large diameter bolts to high and accurate pre-loads. Unlike conventional methods it does not use torque and does not require any forceful turning of the nut or bolt, like impact wrenches, flogging spanners or hydraulic torque wrenches.
How does torque relate to tension?
Torque is the measurement of the force that causes something to rotate, for example, the turning force needed to spin a nut around the threads of a bolt. Tension is the stretch or elongation of a bolt that provides the clamping force of a joint.
Why is torque Tightening important?
those nuts that keep your wheel fastened to the studs on your axle and the bolts that secure and keep your engine assembled were installed at the proper torque to keep them from coming loose. When accurate torque is not applied to the bolts and nuts, they wear out quickly and can cause failure.
What happens if you don’t torque to spec?
Insufficient torque Engines that are running, tend to vibrate. In the case of insufficient torque, it’s the stud or the bolt itself that suffers all the impact, causing it to shear. Alternatively, the engine’s vibrations can cause the bolt or nut to come undone, displacing the tensioner.
How do you convert tension to torque?
The Torque/Tension Equation is a method used to estimate the torque/tension relationship in an assembly. T = (K D P)/12 can be used to developt a torque value that will achieve a certain tension or clamp load.
What is the minimum tension for a 7 8 a325 bolt?
TORQUE ASTM A325
| Bolt Size | TPI | Tension MIN |
|---|---|---|
| 7/8″ | 9 | 39,000 |
| 1″ | 8 | 51,000 |
| 1 1/8″ | 7 | 56,000 |
| 1 1/4″ | 7 | 71,000 |
When do you need tension on a bolt?
When fully tensioned bolts are required, as for slip-critical connections subjected to vibratory or fatigue loading, the installed tension and the attendant friction on the threads will prevent the nut from loosening.
What are the accepted procedures for fully tensioned installation?
Accepted procedures for fully tensioning high-strength bolts can be found in the RCSC Specification Section 8.2 (see also 6.6.3.). If torque is to be used as in the calibrated wrench method as described in the RCSC Specification Section 8.2.2, it must be calibrated on a daily basis for the lot, diameter, and condition of bolts being installed.
How is hydraulic pressure applied to a bolt tensioner?
Step 1: The bolt tensioner is fitted over the stud. Step 2: Hydraulic pressure is applied to the tensioner which then stretches the stud. Step 3: The stud’s nut is wound down against the joint face. Step 4: Pressure is released and the tool removed.
How to account for load loss when tensioning bolts?
This is to account for a load loss in those bolts already tensioned as the next sets are tightened. The load losses are accounted for in calculation and a higher load is applied to allow the first sets to relax back to the target preload. Set-up using a 50% tensioning procedure.