3/8-16,SS, Hex , 3 proj. weld nut torque

[R1H2]

Hi All,

Does anyone have a spec on the designed torque load specs for 3/8-16, Hex, 3 projection, weld nuts?

I have a client that has rejected my parts due to the weld nuts failing under torque.
We used the Nut MFGs weld specs & did an informal load test. Which seemed to be sufficient, for several orders.
Neither the customer nor the MFG had a statement of how to test or what load was spec'd.
Now we've had several failures, per the client.

So, I'm looking for some form of statement to use as a guide for my customer & I to agree on, for setting the
torque load requirement.

Any help is always appreciated.

Thanks in advance.

 

[Screwman1]

What kind of torque? Prevailing torque, K factor, torque to twist it loose, torque to strip the threads, etc?
There are limited standards for SS weld nuts, so it will be interesting to see exactly what the customer is rejecting them for. If it's not in a standard that is called out on the print or PO or it's not detailed on the print, it isn't rejectable.

 

[desertfox]

Hi

I could not find your thread size, however if you click the link below and then click on a particular nut reference it's gives pullout torque etc under performance data

http://www.ejsong.com/MDME/modules/7759g_mechanical_design/welds/welded_joints.pdf

 

[R1H2]

Hi Guys,

1st, thanks for the replys.

Screwman: Its a torque to twist loose. & I agree, Nothing on the PO or Print, then there is nothing to reject against.
(To back this up we have a physical sample that they have approved.)
Etc., Etc. I have plenty of back-up against any liability.
I am hoping to find data to assist them with their statement of requirements.
I Much appreciate your input.

Desertfox: I have only breezed thru the attached file. Lots of data there.
Thanks also for the input. Much appreciated

R1H2

 

[racookpe1978]

You've got to find out what "they" did to strip the nuts. (And "who" the "they" and what they were trying to do when it stripped, or was found stripped.)

See, a nut is threaded on to a stud or bolt (duh he adds) so a couple of things had to have happened for the nut to strip.

Either the applied load was too high (but the nut was tightened properly), and the load pulled the nut "off" of the stud, stripping the threads on the nut rather than the external threads on the stud or bolt. Very, very unlikely, but it could have happened.

Or the nut was being tightened, and the operator put to much torque on the wrench/impact hammer/torque wrench/wrench + lever arm. Much more likely. Still, when that happens, more often the external threads strip, not the internal threads.

Or the nut was properly tightened, the load was within capacity, but the nut galled on the threads when it was being taken apart. If so, you wold see failure only when the threads were tried to be taken apart, but the load could be held correctly and the part would operate correctly. Stainless-stainless and stainless-aluminum mixes are particularly bad.