Bolt torque values

[tristan861]

Hello guys

Simple Question:
How can I get the torque values required to achieve slip resistance using this table?

Is it by: [Bolt Dia x Bolt Pretension x μ]?

μ:mean slip coefficient for Class A or B surfaces

 

[canwesteng]

Calibrated testing of the connection assembly. Turn of the nut or TC bolts are more economical.

 

[bootlegend]

Direct Tension Indicating washers have become my go to method of ensuring pretension. Specifically the squirting style.

 

[desertfox]

Hi Tristan861

Yes the formulae you have posted is correct for obtaining the torque value, however torque is not the most accurate way of bolt tightening and so it depends how accurate you want the bolt preload to be.

“Do not worry about your problems with mathematics, I assure you mine are far greater.” Albert Einstein

 

[JedClampett]

In the AISC manual, there's the "Specification for Structural Joints Using High Strength Bolts." It has extensive information on bolt tightening, including a commentary. Torque is used only with regard to Calibrated Wrench Pretensioning, section 8.2.2. The least painful way, at least to me, is the direct tensioning washers or squirters. With the calibrated wrench, if you're not looking over the installer's shoulder, you have to repeat the operation to verify. With the washers, you can verify with a feeler or just look for the squirted dye.
But the washers come at a cost.