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RE: Structural Bolt Torquing Question

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Curt is right on target.  The A325 A490 RCSC spec. spells it out.  You
should avoid providing torque information because you are implying that you
know the K value accurately.  Verification with a Skidmore on the job site
is essential.  If the special inspector is not using a Skidmore, he is a no
show on the Socratic Plane of knowledge.  If the special inspector is using
a torque wrench, he does not know what he is doing.  Torque wrenches are
only acceptable in arbitration, not inspection.

Regards,
Harold O. Sprague

> -----Original Message-----
> From:	LaCount, Curt [SMTP:Curt.LaCount(--nospam--at)jacobs.com]
> Sent:	Thursday, October 10, 2002 6:42 PM
> To:	Seaint (E-mail)
> Subject:	FW: Structural Bolt Torquing Question
> 
> Eric,
> 
> I believe that the proper requirements are spelled out in the
> "Specification for Structural Joints Using ASTM A325 or A490 Bolts".  To
> summerize; all bolts that are tightened to a fully tensioned condition
> under the four methods allowed must prove the ability to achieve the
> proper bolt tension by testing in a device capable of indicating bolt
> tension.  If the method used to install the bolts also indicates the
> torque used for the installation, it has no direct bearing on whether the
> bolt was properly installed unless verified by tension testing. There are
> too many variables that affect bolt torque to make that an accurate gauge
> of installed bolt tension.
> 
> Curt La Count
> Jacobs Engineering
> Portland, OR
> 
> -----Original Message-----
> From: Eric Green [mailto:EGreen(--nospam--at)walterpmoore.com]
> Sent: Thursday, October 10, 2002 1:01 PM
> To: seaint(--nospam--at)seaint.org
> Subject: RE: Structural Bolt Torquing Question
> 
> 
> This is where the question came about. The specification gives torque
> information when using the turn of the nut method (Table 8.2), but gives
> no information for torque when using torque control.
> 
> I realize the specification does state that the minimum tension should
> be equal to 70 percent of yield and I certainly understand how to
> calculate pre-stress from torque. I guess my question more accurately
> stated would be:
> 
> Who specifies K so that the relationship between torque and tension can
> be determined? Surely one does not depend on the contractor for this
> information? Is it determined by the testing lab for each type of bolt,
> nut and thread compound (if used)?
> 
> Eric Green
> - Fighting my ignorance since 1964.
> 
> -----Original Message-----
> From: LaCount, Curt [mailto:Curt.LaCount(--nospam--at)jacobs.com] 
> Sent: Thursday, October 10, 2002 1:33 PM
> To: Seaint (E-mail)
> Subject: FW: Structural Bolt Torquing Question
> 
> Eric,
> 
> The answer is that nobody specifies torque.  The engineer should however
> specify the tension by referencing the "Specification for Structural
> Joints Using ASTM A325 or A490 Bolts".  This is commonly done from the
> structural notes or in the specifications.  The installation is also
> subject to special inspection.
> 
> Curt La Count
> Jacobs Engineering
> Portland, OR
> 
> -----Original Message-----
> From: Eric Green [mailto:EGreen(--nospam--at)walterpmoore.com]
> Sent: Thursday, October 10, 2002 8:59 AM
> To: seaint(--nospam--at)seaint.org
> Subject: Structural Bolt Torquing Question
> 
> 
> 
> Excuse me for what is probably an obvious question for those of you who
> deal with these connections on a regular basis:
> 
> Who normally specifies the required bolt torque for a slip-critical
> connection? The bolt supplier, steel fabricator or the engineer? Or is
> it some other party?
> 
> Eric Green
> - my ignorance is my own, not my employers.
> 
> 
> 
> 
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