Friday, 14 October 2016

3 way to Tension the Load

What is Tensioning?
Tensioning is the direct axial stretching of the bolt to attain preload. Inaccuracies created through friction square measure eliminated. Massive mechanical effort to form torque is replaced with straight forward hydraulic pressure. the same load can be applied by tensioning multiple studs at the same time.

Tensioning needs longer bolts, and a seats on the assembly around the nut. Tensioning will be done victimisation clastic Bolt Tensioners or Hydraulic buggy.

There are 3 way to Tension:-

2.Hydraulic Tensioners
3.Mechanical Tensioners

1. Tensioning with Heat:-

Gas Bolt Heater:-

Correctly setup a gas bolt heater
Properly adjust oxy-acetylene flame
Correctly adjust air flow
Safely operate a gas bolt heater

Heating causes a bolt to grow in length
Relieves tension on bolt
Gas Bolt Heater is machined from solid Stainless Steel
A single bolt heater can be adapted to fit most bolt sizes by changing the heating tube diameter and length

Select a heating tube that is 1/8” smaller than the hole in the bolt and approximately 3” shorter than the depth of the hole
Install heating tube in bolt heater
Use stainless steel reducing bushing for smaller heating tubes
Use high temperature thread compound
Tighten hand tight
Connect air line to bolt heater
Air pressure should be between 50-100 PSI
Set oxygen pressure to 14 PSI
Set Acetylene pressure to 7 PSI
Use Victor #5-W gas welding tip
Always use check valves
Adjust flame to obtain a carburizing flame
Carburizing flame has an acetylene feather
Insert bolt heater into bolt
Purge bolt cavity with air
Turn air valve off
Insert welding tip into gas bolt heater
Gradually open air valve approximately 1/8 turn
Observe color of heating tube through vent holes in gas bolt heater
Maintain a cherry red color by adjusting air valve
More air is cooler
Less air is hotter
For proper operation a balance of pressure must be maintained between welding tip and heating chamber back pressure
Excess back pressure will result in welding tip back-fire 
If back-fire occurs, close acetylene valve, remove welding tip from bolt heater, purge bolt cavity with air, and restart heating process

Minimum Muscle

Hard on Studs
Must have hole
Rough on gaskets

2.  Hydraulic Tensioners 

Various type of Hydraulic Tensioners 

1.Top Connect
2.Side Connect
3.Hydraulic Nut

                     Top Connect                                  Side Connect                           Hydraulic Nut    
3.Mechanical Tensioner:-

-Multiple Work
-Takes Forever
-Tiny Load Points
-Cant check Results


Gas Bolt Heater