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Re: RE: Welding on bolts

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We have also used "prevailing torque nuts". Theoretically, the tail end of
the nut deforms the threads as it is put on, thereby  creating an effect
similar to whacking it with a bull pin and hammer, although not to the same
extent. I believe Nucor manufactures these, as well as other steel/bolt


At 09:54 AM 3/30/01 -0600, you wrote:
>Damaging the threads is a standard practice.  What about Lock washers,
I've received some complaints that when iron workers torque bolts they
aren't sure if they are torquing up agianst the steel or the lock washer  -
any comments
>I would not recommend welding on bolts either, but if you weld below the
nut and damage the heat propeties of the bolt below the nut, does this
really matter for the connection.  The forces are transferred higher up the
bolt.  Or does the heat transfer extend throught the entire bolt.
>>>> "Sprague, Harold O." <SpragueHO(--nospam--at)> 03/30/01 09:26AM >>>
>Mechanical deformation of threads is very low tech.  
>1.	Tighten the bolt to whatever is required
>2.	Place a the pointed end of a bull pin (AKA drift pin depending on
>regional iron worker vernacular) at the junction between the bolt threads
>and the nut
>3.	Strike the bull pin with a 3 or 4 pound hammer as many times as
>required to crimp the thread flights.  It usually takes only one whack.
>Different iron workers have varying techniques, but the result is the same.
>The thread flights of the nut are mechanically crimped and locked to the
>thread flights of the bolt.
>Harold O. Sprague 
>former iron worker,
>inventor of bolt mechanical thread deformation,
>inventor of the back gouge access hole (as opposed to weld access hole),
>inventor of the wheel,
>inventor of "prior art",
>etc.  (send royalties... grin)
>> -----Original Message-----
>> From:	Boh Jaw Woei [SMTP:boh.jaw.woei(--nospam--at)] 
>> Sent:	Friday, March 30, 2001 8:21 AM
>> To:	'Sprague, Harold O. '; ''seaint(--nospam--at)' '
>> Subject:	RE: Welding on bolts
>>  Thanks! This advice will help a great deal. May you also advise what we
>> mean by mechanical deformation of the treads.
>> jw
>> -----Original Message-----
>> From: Sprague, Harold O.
>> To: 'seaint(--nospam--at)' 
>> Sent: 3/30/01 10:09 PM
>> Subject: RE: Welding on bolts
>> Welding bolts is a bad practice.  High strength bolts are often quenched
>> and
>> tempered and often high carbon.  Even if you account for welding high
>> carbon
>> steel you can impair the strength of the material because the material
>> is
>> quenched and tempered (heat treated).
>> Depending on the location of the weld on the bolt there is a risk of
>> reduced
>> strength, lower ductility, less resistance to fatigue, and less
>> resistance
>> to impact.
>> That said, if it is a small tack weld just to prevent nut rotation, the
>> heat
>> effected zone is very localized and on the opposite side of the highly
>> stressed thread engagement area.  High strength bolt thread engagement
>> lengths are designed to fully develop the bolt and the stress is
>> concentrated in the first few flights of the thread engagement.
>> If the bolt is a low carbon steel with no heat treatment, welding should
>> be
>> less of a problem.  
>> Again it is not a good practice.  Mechanical deformation of the threads
>> is a
>> much less risky method to prevent nut rotation.
>> Regards,
>> Harold O. Sprague
>> > -----Original Message-----
>> > From:	Boh Jaw Woei [SMTP:boh.jaw.woei(--nospam--at)] 
>> > Sent:	Thursday, March 29, 2001 10:27 PM
>> > To:	'seaint(--nospam--at)' 
>> > Subject:	Welding on bolts
>> > 
>> > Need to know the effects of welding on bolts, both high and low carbon
>> > contents. Any comments or advice will be appreciated.
>> > 
>> > sgdon
>> > 
David P. Evangelista, PE
Evan Corporation
8 Reise Road
Jamestown, RI  02835

Ph 401.423.2230
Fx 401.423.2785