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RE: BOLT TORQUE/TENSION RELATIONSHIP

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Title: Message
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.  Even then, the torque is to be quantified to tension values using a Skidmore.  Calculating torque can be done, but again it can vary markedly relative to lubricants or lack thereof. 
 
Pretension is THE goal of bolt tensioning.  Torque is a method of getting the tension, but not an approved installation method for A490 bolts.
 
Regards,
Harold O. Sprague  

-----Original Message-----
From: Ivan Lippi [mailto:ilippi(--nospam--at)dialdata.com.br]
Sent: Tuesday, July 08, 2003 7:45 PM
To: Ivan Lippi; seaint(--nospam--at)seaint.org
Subject: Re: BOLT TORQUE/TENSION RELATIONSHIP

Dear coleagues
 
Tell me if I am wrong on this subject.
 
Regards
----- Original Message -----
From: Ivan Lippi
Sent: Tuesday, June 17, 2003 8:55 AM
Subject: Re: BOLT TORQUE/TENSION RELATIONSHIP

Dear coleague
 
Dont' kid yourself. The proper procedure to tighten high strength bolts is to test them using the Skidmore calibrating device.Many factors influence the torque: type of bolt, lubrication of threads, steel surface condition, length of bolt, thightening by the bolt head or nut, bolt fabricating supplier, and so on. You cannot put together all those variables in a single table like many people erroneously believe.I call those tables "Cheat me please"........
 
Sincerely
 
Ivan Lippi Rodrigues
Civil and Structural Engineer
----- Original Message -----
Sent: Sunday, June 15, 2003 5:07 PM
Subject: BOLT TORQUE/TENSION RELATIONSHIP

Hi!
1.  I need to tension an ASTM A490 bolt to a certain value (somewhat
of a hypothetical question).  I need to calculate the torque required to
achieve this tension.  Could someone tell me how to calculate the
torque?  2.  Do I need to worry about pre-tension?  If yes, will pre-tension
need to be considered in the equation in item 1 above for calculating
the torque?
Thanks for your help!


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