torque

A 10 second googel search found this, hope it helps.

http://appliedbolting.com/Direct_Tension_Indicator_FAQS.php?faq=50#1

Torque = Tension x (nut factor) x (diameter)

http://www.dansmc.com/torque_chart.htm as a beginning. Bolt torque is a wild subject and you'll get answers 40% different. Lubricated . . . non lubricated . . . old . . . new . . . washers . . . no washers . . .

Google suggestions: torque table for 8.8 bolts; grade 8.8 bolt torque; bolt torque table; and various versions of these words, but get 'table' in there each search.

If this is ultra critical duty, the bolt stretch is the only way to be near perfect. Tightening a bolt is just stretching it to some point on its elastic yield curve where it 'clamps' back resisting the stretch with X force. So just begin with stretch and avoid the entire turn method which is subject to 10 variables that effect the result of stretch. Google: Bolt stretch tools; or hydraulic bolt stretchers

Helpful ?

George

This information is available in a multitude of places, on line, Machinery's Handbook, and unlimited sources of technical info.

Unfortunately even if you have the accurate information you are requesting, due to the hiring practice, of most greedy companies, for folks to install your perfectly designed structure you will "probably" have under qualified people installing the bolts in question.

Bottom Line: Accuracy will be totally dependent upon the skill of the people doing the work and thier ability to follow detailed instructions. After you find the information you need regarding your question, be sure you provide the necessary details in your installation instructions and provide an audit trail (inspection) to ensure that the instruction are followed, even if you must watch it being done ( not realistic in most cases).

I work with folks who I would not trust to torque - much less - determine bolt stretch. Not on my life!!! and these folks are experienced shade tree mechanics. The problem is not the accuracy - but the skill level that the cheap corporations are willing to pay for.

Not meaning to be totally negative - but the end item is "COMPLETELY" dependent upon the skill level of the folks you hire.

You are looking at apples and oranges here - Grade 8.8 is a metric specification which you are applying to Imperial/SAE fasteners. You are guaranteed incorrect torques on that basis.

But I suppose a M 25 or M 26 and a 1 inch are close enough when we have +/- 40% accuracy on torque as a discussion point anyway, don't you think?

Here is a good place to get your torque.

http://www.futek.com/boltcalc.aspx

http://www.engineershandbook.com/Tables/torque.htm