ubc international training fund
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1
UBC International Training Fund
PresentsPresents
Tensioning
The following material is intended to make you aware
of the currently acceptable and recognized methods of
performing the tasks described in this presentation.
However, every possible application of these methods
cannot be foreseen and the following material is not
designed to cover every potential application. Therefore,
you must always follow all current procedures and safety
regulations whenever you perform any of the tasks
discussed in this presentation.
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WE SAID BEFORE -
THERE ARE TWO COMMON WAYS TO PRE-LOADA BOLT OR STUD:
1. TORQUE
2. TENSIONING
NOW THAT WE KNOW SOMETHING ABOUT TORQUELET’S DISCUSS TENSIONING
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TENSIONING
TENSIONING = STRETCH THE BOLT,
LET IT SPRING BACK
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TENSIONING
1. HEAT
3 WAYS TO TENSION
2. HYDRAULIC TENSIONERS
3. MECHANICAL TENSIONERS
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TENSIONING
TENSIONING WITH HEAT
Gas Bolt HeaterGas Bolt Heater
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Objectives
• Correctly setup a gas bolt heater
• Properly adjust oxy-acetylene flame
• Correctly adjust air flow
• Safely operate a gas bolt heater
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Design
• 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
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Operation• 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
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• 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
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• 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
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• 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
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TENSIONING
TENSIONING WITH HEAT
(INDUCTION)
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TENSIONING
TENSIONING WITH HEAT
CON’S:•HOT•SLOW•INACCURATE•HARD ON STUDS•MUST HAVE HOLE•ROUGH ON GASKETS
PRO’S:•MINIMUM MUSCLE
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TENSIONING
1. HEAT
3 WAYS TO TENSION
2. HYDRAULIC TENSIONERS
3. MECHANICAL TENSIONERS
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TENSIONING
HYDRAULIC TENSIONERS
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TENSIONING
HYDRAULIC TENSIONERS
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VARIOUS TYPE OF HYDRAULIC TENSIONERS
TOP CONNECTCYLINDER
SIDE CONNECTCYLINDER
HYDRAULICNUT
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TENSIONING
1. HEAT
3 WAYS TO TENSION
2. HYDRAULIC TENSIONERS
3. MECHANICAL TENSIONERS
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JACK SCREW TYPE
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TORQUING THE JACK SCREWS
•MULTIPLIES WORK •TAKES FOREVER
•TINY LOAD POINTS •CAN’T CHECK RESULTS
The EndThe End
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