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[JohnyBoy1]

I have some threaded joints of 1-1/4" x 8 TPI UN bars in 303 SS. How can i work out the safe working Tensile load i can pull on these type of threaded joints. Is there a standard formulae other than the bolt type information available which does not really cater for this problem?
Thanks

 

[Cockroach]

There are closed form solution sets for the problem you are looking for. You can easily find them by searching under "Thread Shear Strength" and noting the equations thereof. Be aware that most models discuss Unified National threads, there is a small minor adjustment to the equations governing shear for Acme and Stub Acme geometry.

In this forum, there are several discussions and solved problems from past postings. Looks for the ones that have been answered with attachments, you will find several worked examples.

Regards,
Cockroach

 

[mcclain]

After you calculate your length of thread engagement required for thread shear strength (I recommend FED-STD-H28) be sure and add in allowances for tolerances and chamfers, etc. Your design length of engagement may be as much as 150% or more of the required length of engagement.

Good luck,
Mark