In heavy construction the bolts that are used to connect steel beams are a high
strength material, significantly stronger than the bolts sold at HomeDepot.
Bolted connections in structural steel are designed to utilize the full
strength of the material, and it is hard to develop that strength if the bolts
are not lubricated before installation.
I've seen demonstrations of this using a Skidmore-Wilhelm machine. They put a
bolt in the machine, put a bag over the gauge so you couldn't see it, then
tightened the bolt to the proper torque. Then they would reveal the gauge and
you could see what tension developed in the bolt. This demonstration was done
with a variety of bolts such as straight out of the package, slightly rusted,
lubricated, etc. The lubricated bolts would develop their full tension, the
others wouldn't.
> If you check out the ARP web site you will see that they claim the use of a
> high pressure lubricant will reduce friction thereby putting more of your
> torque into bolt preload and making that preload more consistent. They
> don't recommend the use of lock tabs or lock washers on their fasteners.
|