The lock washer may be the problem. I thought studies show that they can
actually accelerate loosening.
(in fact we can debate where structural steel bolt connections are
"allowed" to use lock washers")
here's one test result
http://www.boltscience.com/pages/helicalspringwashers.htm
if you have the correct torque, the washer is going to be flat anyhow.
Better to go to flat washers?. (hardened steel: galvanized F436 is the
washer for A325 bolts)
I notice from pictures at that other site showing a Delpha tower failure
from loose bolts, that the connections are essentially flat steel?
Should be able to get pretty high torque there, assuming a325 or grade 5
bolts. (is "large diameter" 1/2" or more?)
Maybe the real problem is not using a wrench with a long enough handle.
Since there's no tube compression issue, these should get over 100 ft
lbs? torque don't know what size bolt it is.
Even if the bolt is galvanized, you should probably use a dry lube spray
on the bolts before tightening.
(if the clamping force is enough, it's hard to believe that you need to
use loctite on a structural flat steel connection)
This is similar to the bolted joint at the bottom of a crankup right? I
use a dry lube spray on 3/4" a325 bolts there.
good point about using new bolts.
-kevin
On 5/6/2010 9:05 PM, Mike wrote:
> Mike,
>
> It almost sounds like they were not tightened down to the correct torque to
> begin with because they should not have come loose with lock washers. I
> would get new nuts, bolts and lock washers and torque them correctly and
> double nut the bolts.
>
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