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RE: Bolt testing

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Mark,

The Skidmore-Wilhelm is used for pretensioned joints and slip-critical
joints to do pre-installation verification testing, as required by Section 7
of the new RCSC Spec (download free at www.boltcouncil.org). Skidmore makes
a Model MS that will do a 3/4" diam by 2" long, but that's as short as it
can handle. There are other manufacturers (Norbar, for example), but these
are imports that may be hard to get. The Japanese also make a unit, perhaps
Tone, but I'm not sure of the name.

For short bolts, such testing can be done with calibrated direct tension
indicators, installing the bolts in a proper size hole in a steel plate.
However, this really doesn't confirm turn-of-nut, so we really on 60+ years
of experience with turn-of-nut and accept the fact that it works. Calibrated
dti's can be used to confirm twist-off bolts, and to calibrate wrenches if
the calibrated wrench is used. To check the dti's themselves, if the dti
pretensioning method is used, you use a longer bolt in whatever Skidmore you
have available.

Short bolt procedures can be found in SSTC's Structural Bolting Handbook,
available for order at www.steelstructures.com.

Hope this helps,

Bob Shaw
SSTC



-----Original Message-----
From: Mark Pemberton [mailto:Markp(--nospam--at)lbdg.com]
Sent: Tuesday, October 30, 2001 4:40 PM
To: 'seaint(--nospam--at)seaint.org'
Subject: Bolt testing


The AISC prescribes four methods for installing slip-critical connections,
however each of these requires calibration using a device capable of
directly indicating the bolt tension.  The Wilhelm-Skidmore device is
the only device I am aware of that has this capability.  We are using
3/4" diameter bolts on this particular job and the testing agency for
the job tells us that the bolts are too short for the machine.  These are
standard 1-3/4" long A325 bolts.  Their machine apparently only tests
bolts that are at least 2-3/4" long (standard 1" dia. bolt length).  My
questions are: 1)  Is the Wilhelm-Skidmore device the only one available
for this type of test? 2) Do they come in different sizes to accommodate
different bolt lengths?
Thanks in advance.

Mark Pemberton, P.E.
Sacramento, CA

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