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Nuts for Anchor Rod

Nuts for Anchor Rod

Nuts for Anchor Rod

(OP)
We have some high strength stainless steel anchor rods and the contractor is having difficulty sourcing high strength nuts to go with them.

Is it reasonable to use a double nut of a lower strength material, using the thread shear capacity of both nuts?  It may be that the steel from one nut or the other starts to yield before it engages the strength of the second nut.

Any thoughts?

Dik

RE: Nuts for Anchor Rod

(OP)
Thanks Mike... I was thinking of the second nut being snugged against the first, or a portion of the face ground off to provide a nut that would be almost twice as long that would provide equivalent resistance of the higher strength anchor rod.

The problem is that it is possible to have nuts machined from a higher strength material, but I was hoping to use two nuts of a more common material.

Dik

RE: Nuts for Anchor Rod

Per your OP, get a copy of the machinery handbook for the answer.  My 26 th edition,  under the Fastner section, page 1490, paragraph "stripping of internal thread",there is a requirement to calculate the "J" factor being a relative strength of the external to internal threads.  

RE: Nuts for Anchor Rod

I was thinking the bolt spec would tell you what nuts you should use.

RE: Nuts for Anchor Rod

Your first concern would be mine also.

 "It may be that the steel from one nut or the other starts to yield before it engages the strength of the second nut."

I'd have the contractor keep searching, unless those nuts are guaranteed to be tight against each other, which I guess you can spec, and then peen the threads to keep them in place or a tack weld (but this may not be a good idea), I'd be wary all of the threads would engage at the same time.

Is there a lower strength coupler or similar device that gives you more threads so you get the same capacity?

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