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Re: Torque vs. Tension in Bolts

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> I have read studies that were
>performed in a lab (ideal conditions) were actual tensions values based
>upon measured torque varies by as much as 100% of the desired tension.
This is a for-instance, not a proof; there are probably just as many 
studies around which show the opposite, namely that torquing _will_ 
produce repeatable bolt tension. The secret is taking measures to insure 
that friction--the major contributor to torque--doesn't change any more 
than necessary. Clean threads are very important, and a lubricant helps 
greatly. Both are important to a sound joint, whether you use torque or 
something more elegant to determine preload. If you use rusty bolts with 
dinged-up threads and whatever washers and nuts K-mart has on sale that 
day, maybe you'll get lucky and the joint will hold--or not.

Christopher Wright P.E.    |"They couldn't hit an elephant from
chrisw(--nospam--at)        | this distance"   (last words of Gen.
___________________________| John Sedgwick, Spotsylvania 1864)