One leg of a self supporting tower falls "up" - it fails in tension.
My nuts are tight after torquing bolts to 140 ft-lbs...
Grant KZ1W
On 6/25/2013 12:59 PM, Mitchell, Dennis C wrote:
"I've never seen a Tower fall UP."
I'd only torque bolts enough to keep your nuts from falling off...
K8UR
-----Original Message-----
From: TowerTalk [mailto:towertalk-bounces@contesting.com] On Behalf Of KM5VI
Sent: Tuesday, June 25, 2013 3:28 PM
To: towertalk@contesting.com
Subject: [TowerTalk] FW: UST bolt Torque question
Snug tight is a standard term commonly used in the design of bolted connections
that are not slip-critical. Slip-critical connections rely on the friction
created by the clamping action of the threaded connection and require a minimum
fastener torque or bolt stretch specification to achieve the design friction
value. Bolted connection design based on the simple shear and/or bearing
strength of the fastener do not rely on joint friction, and thus the assembly
torque is non-critical provided that it is tight enough to eliminate slop in
the joint that might over time from load cycles (bolt loosening).
FYI - I have found a spud wrench useful for snug tight connections on my
crank-up tower base connections - it is a short wrench that is designed to be
struck with a hammer.
Hope this helps.
Matt
KM5VI
-----Original Message-----
From: TowerTalk [mailto:towertalk-bounces@contesting.com] On Behalf Of Jim
Thomson
Sent: Tuesday, June 25, 2013 7:39 AM
To: towertalk@contesting.com
Subject: [TowerTalk] UST bolt Torque question
I asked UST how much Torque should be used on both the 12 x 1.125 inch anchor
rods....and also the 18 x 1 inch leg bolts.
I also told em I used never seize on both anchor rods and legs bolts. Also
told em the anchor rods are 104 ksi yield strength..and came from portland
bolt...and are 60 inchs long each.... with 6 inch threads
on each end. Told em that the 18 x leg bolts are
A325 bolts and are 3 inchs long each. Everything has heavy duty flat
washers and slightly oversized nuts on em.
Their reply was...... snug fit ! This is for my UST HDX-689 tower. This
is the old style 689..that weighs 5000 lbs..without the ants and mast, but that
weight includes the bearings and small PP rotor. The crane operator
weighed the tower when it was unloaded.
What is ..snug fit ? Trying to get answers from UST at times can be
exasperating.
Does anybody even know ? I was thinking perhaps 125 ft lbs for the
anchor rods......and 100 ft lbs for the leg bolts. Leg bolts can always be
replaced...
anchor rods cant.
Tnx... Jim VE7RF
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