Nuts for Anchor Rod

[dik]

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

 

[msquared48]

Don't know if this oould help or not, but you might want to keep tabs on this thread from the Mechanical Other Topics forum:

To translate axial F to tensile force of screw
thread404-300214


Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask

 

[dik]

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

 

[chicopee]

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.

 

[JStephen]

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

 

[CTSeng]

These guys have a lot of good info on their site. More than once have they helped me when a contractor tells me the material is not available for a bolt or nut.

http://www.portlandbolt.com/technicalinformation/nutcompatibility_nutchart.html

 

[a2mfk]

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?

 

[a2mfk]

If you go with double nuts, this is a good thread:

thread507-237906