Very well put Mickey and I agree with your 90% comment as well.
Page 51 of the Research Council on Structural Connections (RCSC)
Specification for Structural Joints Using High-Strength Bolts gives us a
technical definition for snug tight:
http://www.boltcouncil.org/files/2009RCSCSpecification.pdf
KM5VI
-----Original Message-----
From: TowerTalk [mailto:towertalk-bounces@contesting.com] On Behalf Of
Mickey Baker
Sent: Tuesday, June 25, 2013 2:38 PM
To: KM5VI
Cc: towertalk@contesting.com
Subject: Re: [TowerTalk] FW: UST bolt Torque question
There are actually technical definitions for this. As you might imagine,
engineering structures like towers, buildings and bridges, engineers need to
effectively communicate to laborers how they'd like things tightened.
Here's an interesting technical treatise from a fastener manufacturer's
point of view that defines "snug tight" as:
*Snug Tight = The tightness that is required to bring the plies into firm
contact (Typically obtained with a few impacts of an impact wrench or the
full effort of an Iron-worker using an ordinary spud wrench).
*
The original doc can be found at:
http://www.selfdrillers.com/brochures/TDS012-Turn-of-Nut%20Installations.pdf
Dollars to donuts that the average iron worker will normally tighten a nut
tighter than 90% of hams. Ironworkers put the world together - and sometimes
take it apart!
73,
Mickey N4MB
On Tue, Jun 25, 2013 at 3:27 PM, KM5VI <km5vi@flukey.cc> wrote:
> 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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>
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--
Mickey Baker, N4MB
Fort Lauderdale, FL
*"Tell me, and I will listen. Show me, and I will understand. Involve me,
and I will learn." *Teton Lakota, American Indian Saying.
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