Welding HS Nuts

[DWHA]

I have been told it is not allowable to weld HS Bolts, but what about the nuts. I have a connection that will be inaccessible in the filed and I would like to allow the fabricator to weld the nuts to the back side of a plate.

My colleague wants to do this, but I am not sure it is the best idea. So waht I am really looking for is code reference stating if it is allowed or not.

Thanks in advance.

 

[lkjh345]

My 2 cents:

If all you are doing is tack welding the nut in place, so that the bolt can be installed in the feild, and the shaft of the bolt will take the load in the connection by shear in the final installation, I do not see a problem; and in fact do this myself when circumstances dictate.

I would only use this on connections using bearing bolts. Would not use this on Slip-Critical (friction) bolts, as I am not sure this would allow the bolts to be properly tensioned.

If all your using the weld for is to hold the nut in place while the bolt is installed, I don't see a problem.

JMHO.

 

[HgTX]

If it's not okay for the bolt head, why would it be okay for the nut?

Hg

Eng-Tips policies: faq731-376

 

[kilroy73]

I don't know the answer, but did you check applicable ASTM for clues?

HgTX - One possible reason it may be ok for nuts but not bolt heads (and again I don't know that it is) is they may have different chemical composition.

 

[sdz]

Generally it is not a good idea to weld nuts because the chemical composition makes them unsuitable. (I think high sulfur leads to porosity). Check with suppliers; you might be able to get weld nuts which are suitable for welding.
My source is the Ajax Handbook.

 

[csd72]

Weld a plate either side to act like a spanner and stop it twisting then weld a keeper bar over the top so it doesnt fall out.

 

[DWHA]

Here is the response that I received from AISC.

"Nuts are typically hardened and quenched. Therefore welding the nuts will have detrimental effects on their physical properties."