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RE: Twist off bolts (was: Bolt retightening)

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Thanks, Harold for the plug on the seminars. For those who are now
interested, my seminars are in Buena Park next week (one on Steel
Connections: Seismic Applications and one on Structural Welding: Design and
Specification) and the following week, the two day-seminar on Structural
Steel Inspection. I then repeat these three seminars in South San Francisco
the last two weeks of October. Seattle gets SCSA and SSI right after
Thanksgiving, and Vegas is in December (Structural Steel Inspection only).

I spend about 3-1/2 hours on bolting in the Structural Steel Inspection
seminar. Always a fascinating discussion about what really happens and some
of the lunacy that takes place from the engineering, construction and
inspection disciplines. 

Seminar info at www.steelstructures.com

Shameless plug complete.

Bob Shaw
SSTC

-----Original Message-----
From: Harold Sprague [mailto:spraguehope(--nospam--at)hotmail.com] 
Sent: Wednesday, September 28, 2005 6:04 PM
To: seaint(--nospam--at)seaint.org
Subject: RE: Twist off bolts (was:Bolt retightening)

Tom,
That is correct.  That is why the twist off manufacturers are conservative 
in the torque it takes to twist off the bolt.  Another critical factor is 
the lubricant.  If you have a large complicated structure and the steel is 
erected and plumbed.  Then you take a couple of weeks off because of the 
rainstorms that blew through.  You need to pull a pretty good sampling of 
bolts, load them into the Skidmore and verify if you are getting the 
tension.  If not, you need to pull the bolts and relubricate them.  If the 
bolts have surface rust, you can be off on the tension by a factor of 2.

That is why special inspection by a QUALIFIED inspector is important.  You 
can make it fool proof and require the DTI washers plus the DTI bolts.  That

way you can see on each and every bolt if you have the proper tension.  When

the washer squirts, you have the tension.  And you have the ease of 
installation offered by the twist off bolts which use electric wrenches and 
are light and easy to operate.

I think it would be fun to take some engineers out on a site, and have them 
install bolts using the various techniques.  It is also entertaining to 
remove the lubricant from a few bolts and even have some with light surface 
rust.  Then put them into the Skidmore and see how much tension you are 
getting.  Or you can keep your clothes clean and attend one of Bob Shaw's 
highly educational presentations on bolt installation.

I have done both.  I am a slow learner due to too much suds sucking as an 
iron worker back in my bullet proof days of youth.

Regards,
Harold Sprague





>From: "Tom Skaggs" <tom.skaggs(--nospam--at)apawood.org>
>Reply-To: <seaint(--nospam--at)seaint.org>
>To: <seaint(--nospam--at)seaint.org>
>Subject: Twist off bolts (was:Bolt retightening)
>Date: Wed, 28 Sep 2005 14:06:16 -0700
>
>The problems with relating bolt tension with torque (i.e. calibrated
>torque wrench) were well documented in this thread.  I also understand
>DTIs are a direct measurement of bolt tension, but aren't the twist off
>bolts just another torque based method and not measuring direct tension.
>I've briefly looked at the NUCOR website, perhaps I don't understand the
>twist-off mechanism.  Please explain?
>
>Tom
>
>________________________________
>
>From: Michael Hemstad [mailto:mhemstad(--nospam--at)mbjeng.com]
>Sent: Wednesday, September 28, 2005 13:36
>To: seaint(--nospam--at)seaint.org
>Subject: Bolt retightening
>
>
>Kevin,
>
>I concur with Harold (I'm sure he's relieved to hear that).  One of the
>huge and seldom-quoted advantages of twist-off bolts is that they can be
>inspected with certainty, from the ground, with very little effort on
>your part.  If the spline is twisted off, it's done.  Therefore it is
>entirely feasible to inspect every bolt on a project.  It really adds to
>everybody's peace of mind.  And, as Harold notes, it's also probably the
>cheapest solution.
>
>I've never had to spec these bolts into a project, because they're
>universally used around here; but if I saw ironworkers using the
>old-style bolts and spud wrenches, I'd start asking a lot of questions.
>
>Mike Hemstad, P.E.
>
>Meyer Borgman Johnson
>
>Minneapolis, MN
>
>------------------------------------------------------------------------
>--
>
>From: "Harold Sprague" <spraguehope(--nospam--at)hotmail.com>
>
>To: seaint(--nospam--at)seaint.org
>
>Subject: RE: Bolt retightening
>
>Kevin,
>
>Torque wrenches are only supposed to be used in arbitration in the
>
>installation of A325 or A490 bolts according to the RCSC. Torque is a
>very
>
>poor indicator of tension in a bolt. The tension is what you are trying
>to
>
>achieve.
>
>Getting a Skidmore on the project site (hydraulic tension indicating
>device)
>
>is not a big deal for most iron workers, and is fairly routine.
>
>Because of the variability, I would NEVER allow calibrated wrench bolt
>
>tightening.
>
>When you boil it all down, the best and probably cheapest solution is to
>
>replace all of the bolts with the tension indicating bolts using the
>
>splines. The installation wrench rotates the nut while holding the bolt.
>
>The spline snaps off when the appropriate tension is achieved. You still
>
>have to install the bolts to "snug tight" with the faying surfaces in
>full
>
>contact. And you still need the Skidmore on the site to verify the
>
>appropriate tension for the tightening procedure you select. The
>
>installation is a lot easier using the twist offs as opposed to using a
>
>pneumatic wrench or a spud wrench with a cheater (for turn of the nut).
>The
>
>labor is where you will save the money over other installation methods.
>And
>
>the QC is better.
>
>If you want the ultimate in reliability, ease of installation, and 100%
>QC,
>
>use the DTI "Squirter" washers with "twist off" bolts. You get the ease
>of
>
>installation with the "twist off" wrench and you get the tension
>indication
>
>that the "squirter" washers provide.
>
>If you decide to go against my incredibly sage advice and use turn of
>the
>
>nut, use match marking with a paint stick. And never tighten bolts
>without
>
>a Skidmore.
>
>Regards,
>
>Harold Sprague
>
>
>
> >From: Kevin Below <kevinbelow(--nospam--at)videotron.ca>
>
> >Reply-To: <seaint(--nospam--at)seaint.org>
>
> >To: seaint(--nospam--at)seaint.org
>
> >Subject: Bolt retightening
>
> >Date: Mon, 26 Sep 2005 22:48:26 -0400
>
> >
>
> >I am in need of some guidance on the right technique for retightening
>
> >bolts on a 40-year-old steel structure....
>
>
>

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