Bolt Pre-tension

[harrai]

Hi All:

I am torqueing the nut so that assembly does'nt come out, I knoow the pre torque but I do not know how much this torque will create pre tension on nut and bolt.

So could anyone tell me the basic relation between torque and tension in a bolt.

Well I used T=FKD where F is the tensile force
T=torque, D is the nominal dia of bolt/nut, K is torque coefcient.

Thanks

 

[MintJulep]

faq725-536

faq725-600

 

[desertfox]

Hi harrai

Depends on how accurate you want the pre-load.
If your using a wrench then the pre-load will be subject to
+/- 20% or thereabouts.
The formula you have used is very approximate.
have a look at this site also:-

http://www.roymech.co.uk/Useful_Tables/Screws/Preloading.html

Regards

desertfox

 

[dvd]

If you want to accurately correlate bolt tension and torque a Skidmore-Wilhelm bolt tension calibrator is the way to go.

http://www.skidmore-wilhelm.com/bolt_testing.htm

 

[rb1957]

i think we're going off on a tangent. the OP has asked only to hold the pieces together, not to design them to withstand a specific tension load (which they may well do, but like most things here, this'll unfold with further posts !)


try goggling or yahooing "bolt intsallation torque design guideline" ... i got this reference for you ...

http://www.shurjoint.com/pdf/B-17 Bolt torque.pdf