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RE: Stainless Steel Nuts

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I used to design temporary shoring to jack up freeway bridges and the like.  The shoring had to be jacked up and shimmed tight to take the demand off the bent cap.  In order to preclude sliding failure in the shim stack, we used high-strength Williams rods to bolt the shoring to the foundation squeezing the shim stack such that the friction between the shim plates was higher than the shear demand.  The contractors always used a calibrated torque wrench to achieve the desired tension in the threaded rods. I use the term wrench loosely as the device looked much more like an oversized air-driven impact wrench.
 
Can you use a similar approach?
 
Nick Blackburn, PE
 
 
-----Original Message-----
From: Nels Roselund, SE [mailto:njineer(--nospam--at)att.net]
Sent: Tuesday, November 12, 2002 7:49 PM
To: seaint(--nospam--at)seaint.org
Subject: Stainless Steel Nuts

I want to detail a connection that will use a calibrated jack to pull a stainless steel threaded rod to a predetermined tension, and then transfer that tension to a nut by tightening the nut until the jack load goes to zero.
 
Will galling of the threads be a problem?  Will use of Acme threads help?  Is there a lubricant that will minimize the probability of galling?  The structure will be of 316L.  Is there another stainless steel that would be better for the rods and nuts of this particular detail in order to minimize galling?
 
Nels Roselund
Structural Engineer
South San Gabriel, CA
njineer(--nospam--at)att.net