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Calculate tension in torqued bolt 6

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patelam

Civil/Environmental
Jan 27, 2022
36
How do I calculate the tension in bolt based on the torque applied?
 
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@GBTorpenhow - Can I use it for Stainless Steel bolts connected to SS plates ?
 
Except that stainless steel may have wildly different coefficients of friction due to galling. If you need to have an accurate tension with stainless steel I suggest using torque to yield or torque to angle depending on the rigidity and variability of the joint.
 
Patelam,

You can only get a range of numbers which by the look of the link is a factor of 3. That sounds about right.

Torque to tension is dependent on a number of factors which are difficult to control or determine. If you want definitive tension then use a hydraulic bolt tensioner.



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K-factor is key to your answer; Without knowing it, you're guessing numbers, and will only find a range like LI mentioned. Practice is you'll only find it by testing, and it only applies when the variables affecting K-0factor, dont change

Huub
- You never get what you expect, you only get what you inspect.
 
XL83NL said:
and it only applies when the variables affecting K-0factor, don't change

And that's about as rare as rocking horse shit....

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
 
Attached is some info about the threshold galling stress of various SS combinations in contact and sliding.
From a mere 2ksi to over 50 ksi.

For a cranky combo of SS fasteners, material hardness and smoothness of the threads can only do so much.

I don't remember the materials, but a precision spindle company made some SS spindles for a centrifuge or something. We routinely made gorgeous precisely ground threads in many ferrous materials.
Basically as soon as there was ANY load on the locknut when beginning to tighten against the bearing preload, the nut seized HARD to the spindle threads.
The nut simply had to be cut for removal.

 
 https://files.engineering.com/getfile.aspx?folder=10869380-a847-47a7-a7e9-df79117a2e07&file=ss_galling_1.png
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