Question on Pull out Force for a Threaded Joint

Depends on many factors such as material, thread engagement, size, thread type etc. You'll need to provide more details if you want an answer but I would suggest you look at Machinerys Handbook, that will give you all the info you need.

Thread pull out load charts - Practical Machinist

Google gives plenty of help.

The only way to know for sure is destructive testing....

http://www.pullouttesting.co.uk/pull-out-testing-equipment.html

Do you mean a threaded insert like a Helicoil, or just a tapped hole in metal?

If it's the latter, for a reasonable thread depth, say 2x bolt diameter, and assuming the tapped block is same strength grade as the bolt, my guess is pullout load won't differ much from the bolt breaking load. This is based on the observation that if you overtighten a bolt it's about as easy to break the bolt off as to strip the threads. Though this might be somewhat harder on the bolt than a straight pullout load, as torsion is also involved.

Depends on the bolt.

All bolt manufacturers publish pull out and shear forces for their bolts.

Ultimate Yield Strength

Take the minimum yield in psi of the ASTM grade (see our Strength Requirements by Grade Chart for this value), multiplied by the stress area of the specific diameter (see our Thread Pitch Chart). This formula will give you the ultimate yield strength of that size and grade of bolt.

Ultimate Tensile Strength

Take the minimum tensile strength in psi of the ASTM grade, multiplied by the stress area of the diameter. This formula will give you the ultimate tensile strength of that size and grade of bolt.

Shear Strength

First, find the ultimate tensile strength using the formula above. Take that value and multiply it by 60% (0.60). It is important to understand that this value is only an estimate. Unlike tensile and yield strengths, there are no published shear strength values or requirements for ASTM specifications. The Industrial Fastener Institute (Inch Fastener Standards, 7th ed. 2003. B-8) states that shear strength is approximately 60% of the minimum tensile strength. For more information, please see our FAQ on bolt shear strength considerations.

http://www.portlandbolt.com/technical/faqs/calculating-strength/

Also depends on what the bolt's bolted into.

Unfortunately the OP isn't aware that that matters either. Not sure what's he is aware of.

Agree Much depends on the carbon content of the steel, or whether it is an alloy etc..eg the difference in material grade between B7 and B14 studbolts. Both are in common use. Temperature also plays a factor, as the bolt will deform more readily under high temperature. The manufactures test these parameters before certifying their bolts suitable to a partictular application.

I once saw a figure of 500kg published as the shear stress for a 12mm bolt, but have actually witnessed a 700kg lift on a 12mm i-bolt (supplied with electric motor).

Shear and tensile strengths aren't the same.

That low shear stress rating takes into account mal-rigging of the eye and the subsequent prying that accompanies dodgy rigging and hoisting.

FOS is high.

If you load the 12mm eye straight up its axis you can lift a lot more than 700kg.

!2mmØ is a nice size. I has a look to it.....

No you don't. You need the safe working load instead. You need the yield stress of the bolt, and need to keep below 2/3 of that for the actual load. You also need to establish the yield stress of the material you are bolting into, and keep below 2/3 of that too.

Why can't you bolt through, and put a nut on the bolt instead?

...and weld the nut in place so it's captive if so desired.

I was going to suggest not much force at all if it was set into a bowl of custard... we can't be sure.

Not including stripping threads from over tightening, I've always found that the bolt shank fails long before the threads start shearing when these things are in tension...that's if the bolt and threaded hole are the same material.