Bolt Torque

First of all, do you wish to:

• calculate how much theoretical resistance there may be when trying to turning a nut or bolt head (ie "torque"?

or...

• determine how tight a fastener has to be so that your equipment doesn't leak or come apart or otherwise fail (ie bolt load / bolt stress)?

Although most people want the latter, they often mistakenly ask for the former. The two are vastly different! In the real world "Torque" has limited or dubious relationship to a fastener's "tightness" (or lack thereof). This misunderstanding often results in significant frustration and cost when a joint with "properly torqued" bolts, fails

Rather than getting into another long technical discourse, here's a link that will explain: Torque Danger

And, here's a link to where you can download some simple spreadsheets that might provide you with a basic starting point : Bolting Technical Downloads

Hi ref your query calculate bolt torque.

the formula is T = ( k x d x P )/12

where T is in ft/lbs,

"k" is coeffecient of friction usually 0.12 - 0.15 could be aslow as 0.05 if oiled oras high as 0.5 if rusted.

d is nominal diameter in inches

P is Stress in lbs.

example. k= 0.05, d= 0.75in P= 30,000lbs

T = ( 0.05 X 0.75 X 30,000 )/ 12 = 93.73 ft/lbs

THIS SHOULD ONLY BE USED AS GUIDE, CHECK WITH MANUFACTURER TO BE PRECISE.

Unfortunately, neither the manufacturer nor anybody else can tell you what the K Factor will be

Therefore, the "specified" torque may result in a bolt that is too loose or too tight for actual conditions!