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RE: BOLT TORQUE/TENSION RELATIONSHIP

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Jim, 
A hydraulic tensioner is a device which attaches to the threads beyond the
nut.  It applies a tension load on directly on the bolt.  The nut is then
turned to lock in the tension.  The nuclear and petrochemical industries
have used these for many years to apply a specific tension load on a bolt.
Check out:
http://www.htico.com/vmspec-index.htm
http://www.biach.com/Home/home.html
http://www.tentec.net/

You can also use a calibrated load indicating washer:
http://www.turnasure.com/index.htm

You can still just use 2 wrenches to tighten a bolt.  The turn of the nut
method is what I first learned as an iron worker shortly after dirt was
invented.  The trick is to use match marking with a paint stick.  It saves a
lot of heart ache after a rain storm hits washing off all of the chalk marks
and you don't know how to inspect a bolt installation.  

Torque wrenches CAN work reasonably well inside a machine manufacturing
facility where all of the bolts have no burrs, have no corrosion, and have a
nice coating of lubricant.  But even there, if you take a sampling of bolts
with varying lubricants, burring, and surface conditions and load them into
a Skidmore, you will see that tension in bolts will not be all that
consistent.

Regards,
Harold O. Sprague

-----Original Message-----
From: jim jensen [mailto:doublejtp(--nospam--at)yahoo.com] 
Sent: Friday, July 11, 2003 12:09 AM
To: seaint(--nospam--at)seaint.org
Subject: RE: BOLT TORQUE/TENSION RELATIONSHIP


Please to tell me, just what is a "Hydraulilc
Tensioner" and how does one go about using them in the field??,interesting
info on this Board, of which, just how does one go about "tighening" a bolt,
if a person, just plain cannot use two wrenches. I'am  also curious as to
what applications this needs to be so seriously addressed. I thank you, Jim
Jensen, just a residential builder.
--- "Sprague, Harold O." <SpragueHO(--nospam--at)bv.com> wrote:
> I think that Charlie Carter's morning cup of coffee
> has kicked in now enough
> for spell check to work, but his point is correct.
> The front of the AISC
> "Specification for Structural Joints Using ASTM A325
> or A490 Bolts" states
> that it was prepared by RCSC Committee 15.  The
> recommendations by AISC are
> the same as the RCSC.  
> 
> Aside from Charlie's spell check lapse, there are 4
> methods listed in the
> RCSC that are intended to "pretension" a bolt.  None
> of them will allow you
> to just use a torque wrench and pretension bolts.
> The closest thing is the
> Calibrated Wrench in Sec. 8.2.2.  It states that
> "... Torque values
> determined from tables or from equations that claim
> to relate torque to
> pretension without verification shall not be used." 
> The commentary is also
> a good read when it comes to this topic.  Frankly
> the effort to properly
> install and inspect bolts using the Calibrated
> Wrench method are so
> difficult, I don't allow it in the specifications
> that I write, and I can't
> even recall a project in the last 20 years in which
> Calibrated Wrench was
> used.  
> 
> The torque wrench is allowed ONLY as a means of
> arbitration.  The torque
> wrench is NOT allowed as a method of  installation,
> nor is it allowed for
> inspection.
> 
> The goal is to provide a pretension in the bolt per
> RCSC Table 8.1.  Torque
> is irrelevant. Now with all of that, I must confess
> that I have used torque
> as a method to provide a pretension force on some
> anchor bolts.  But I was
> conservative, it was not all that critical of an
> application, and I required
> some serious inspection.  On critical anchor bolts,
> I require hydraulic
> tensioners.
> 
> Regards,
> Harold O. Sprague
> 
> 
> -----Original Message-----
> From: Christopher Wright
> [mailto:chrisw(--nospam--at)skypoint.com]
> Sent: Wednesday, July 09, 2003 11:37 PM
> To: ?
> Subject: RE: BOLT TORQUE/TENSION RELATIONSHIP
> 
> 
> >Torquing bolts is not an accepted method of bolt
> pretensioning by the
> >RCSC. The only "torque" method discussed in the
> RCSC is for arbitration
> >ONLY.
> Why do you suppose RCSC takes this position so much
> different than that
> taken by the AISC? Have safety issues been
> uncovered, using the AISC 
> calibrated wrench or turn-of-the-nut methods been
> founf defective?
> 
> Christopher Wright P.E.    |"They couldn't hit an
> elephant at
> chrisw(--nospam--at)skypoint.com        | this distance"   (last
> words of Gen.
> ___________________________| John Sedgwick,
> Spotsylvania 1864)
> http://www.skypoint.com/~chrisw
> 
> 
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