torque tensioning

[300909]

does anyone know how to convert a torque to a axial tension force.
I am looking for tables where you can specify the amount of torque require to tension a rod.
Does anyone have any tips

 

[ishvaaag]

Look for sheet

t29u.pdf

in MARYLAND METRICS site

http://www.mdmetric.com

Torque issues maybe are actually dealt with in items 275 and following in the following site

http://www.mdmetric.com/home3.htm#tech

 

[desertfox]

Hi 300909

This formula is a good approximation :-

F= T/(0.2*d)

F= axial force

T= torque

d= nominal diameter of bolt

0.2 is the coefficient of friction.

regards
desertfox

 

[BryanStein]

You're about to make a HUGE mistake. TORQUE CANNOT be converted to TENSION. AISC allows erectors to callibrate torque to tension on an individual site basis and forces consistency with thread lubrication, etc. As soon as a change is made, the correlations are invalid.

I suggest you use the turn of the nut method suggested in the AISC code. Another option is to use load indicator washers.

DO NOT correlate torque to tension unless you have gone through a calibration process first.

 

[barryadamson]

I agree with BryanStein.

We had a roll out section for a tunnel (about 3.2 m diameter) that had 3 rows (50 each) of 50 mm dia bolts. The specification was for the bolts to be clean & lightly oiled & then tightened up to (in those days) 3,800 lb ft torque. Tensioned to 50 %, 80 %, 100 % & then 100 % again to a pattern (of course). The problem was that the bolts were tightened up after they were lubricated with petrolatum paste (it appears that they did not have any oil handy). Most bolts 'necked' & had to be replaced.

As BryanStein said 'DO NOT correlate torque to tension unless you have gone through a calibration process first.'

Regards

Barrya