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Re: Galvanized TC Bolts

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David,
Thanks for sharing your knowledge of twist-off bolts.  I wonder if you could
elaborate on your last sentence : "Unfortunately, contractor
misunderstanding and misuse of twist-off bolts is rampant"?  If there is
generally poor practice using these in the field, I would like to know what
to look for so I could perhaps discuss these items with the erector before a
job begins.  I also did not know that the DTI washers could be used with the
TC bolts.  Is the TC washer replaced with the DTI washer?  Is there still a
benefit to using the TC bolt in a slip critical connection if you need to
check the DTI anyhow?
Thanks for your help.
Ken

Kenneth S. Peoples, P. E.
Lehigh Valley Technical Associates
1584 Weaversville Road
Northampton, PA 18067-9039
Phone: (610) 262-6345
Fax: (610) 262-8188
e-mail: kpeoples(--nospam--at)lvta.net

----- Original Message -----
From: "David Sharp" <Ausgang(--nospam--at)e46fanatics.com>
To: <seaint(--nospam--at)seaint.org>
Sent: Wednesday, October 31, 2001 6:05 PM
Subject: Re: Galvanized TC Bolts


> Ken,
>
> Mr. Hunt's observations on twist-off bolts are noteworthy, and I have a
few
> additional ones.
>
> The tips of ANY twist-off bolt can stick in the end of the wrench if they
> get dirty or slightly rusty.  Some 'tip' designs are more susceptible than
> others.  This applies to plain finish ones as well.  I see this about once
a
> week this time of year, and have had it happen to me numerous times while
> I'm teaching bolting crews how to use these devices.
>
> Most manufacturers of torque-control twist-off bolts do not galvanize
them,
> as this makes the torque-tension relationship under which these devices
> operate much more difficult to control.  The twist-off bolt is of course a
> torque-control based system in which the fastener engineer designs the
> system so the break-neck shear element snaps off at precisely the same
> torque every time.  (How that level of torque correlates to tension
depends
> upon many factors ----- but the predominate factors which effect the
tension
> actually generated are storage and field conditions moreso than
manufacturer
> production or quality issues.)
>
> In Japan, where these devices are used extensively, use of galvanized
> torque-control bolts is not permitted.  You should know also that the ASTM
> specification for twist-offs, (ASTM F1852), strictly forbids lubrication
or
> plating of twist-off bolts by any party other than the original
> manufacturer.  Any party that does so would in effect 'become the
> manufacturer' and thereafter be responsible for retesting and recertifying
> the fasteners as though they were newly manufactured.  (Failure to do so
> would also be a violation of the Fastener Quality Act.)
>
> There are a number of sources for twist-offs here in North America.
LeJeune
> is among the better known names, although they are not a manufacturer in
the
> traditional sense of the word.  They have their parts produced in the
> facilities of other companies which are willing to apply LeJeune's
'private
> label' headmark to the fasteners.  For many years LeJeune's twist-offs
were
> exclusively produced by Lake Erie Screw Corp in Cleveland, Ohio.  More
> recently I gather they have also had their fasteners produced by Infasco
and
> perhaps by others.  Regardless of the source of supply, ASTM F1852
requires
> that all twist-offs be supplied as complete bolt/nut/washer assemblies.
> (i.e. not in separate cans)
>
> To resolve any wrench clearance issues, there are special wrenches
available
> which enable shearing of the break-neck element in rather close quarters.
> Some of these are actually hand (rather than electric) operated, and the
> greatest variety of these wrenches are available from GWY, Inc. (603)
> 547-3800.
>
> In my opinion, twist-off bolts are the best system currently available for
> efficient tightening of shear/bearing connections.  However, due to common
> construction practices, the same can not be said for use of these devices
in
> slip-critical or full tension connections.  For such connections, use of
> either turn-of-nut style 'match-marking' or use of a Direct Tension
> Indicator (in addition to the t/o bolt) provides a means to inspect that
the
> (fixed) torque value used to shear the break-neck was indeed sufficient to
> generate specified tension/clamp force.  Unfortunately, contractor
> misunderstanding and misuse of twist-off bolts is rampant.
>
>
> David Sharp
> TurnaSure LLC
> 57 E. 11th St. 8th Fl.
> New York, NY 10003
>
>
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