How do I calculate tightening torque???
How do I calculate tightening torque???
(OP)
This is probably a simple question to some who does it everyday, but I'm struggling....
How do I work out the torque that should be applied to nut to give a specified 'clamping' force on a gasket.
I have a connection comprising of a single nut(female thread!) screwing on to a male threaded connection.
These when mated together compress a ring gasket.
The threads are 2.5" right hand Whitworth with 5 (five) teeth per inch. I have 30mm of thread. The threads are cut from Hastelloy C276.
I assume the torque is a function of thread contact area and friction between the threads.
Any guidance will be greatly appreciated!
Biggy
How do I work out the torque that should be applied to nut to give a specified 'clamping' force on a gasket.
I have a connection comprising of a single nut(female thread!) screwing on to a male threaded connection.
These when mated together compress a ring gasket.
The threads are 2.5" right hand Whitworth with 5 (five) teeth per inch. I have 30mm of thread. The threads are cut from Hastelloy C276.
I assume the torque is a function of thread contact area and friction between the threads.
Any guidance will be greatly appreciated!
Biggy





RE: How do I calculate tightening torque???
This formula will calculate what torque will generate what preload. It requires SI units, so you will need to convert.
If you do change to M/MJ threads, the 0.56 factor will need to be changed to 0.58.
M = F/1000 * [(0.16*P) + (0.56*d*mu) + (mu*D/2)]
where
M = input torque in N m
F = preload in N
P = pitch in mm (this is the inverse of threads per inch)
d = pitch diameter in mm
mu = friction coefficient
D = (dout+din)/2
dout = outer nut contact diameter in mm
din = inner nut contact diameter in mm
Cory
cpadfield@omninmetalslab.com
RE: How do I calculate tightening torque???
Hasalloy may have a different friction coefficient. Check whether galling is a problem. If it is then apply an anti-galling compound, or simply grease the threads before installation.
Russell Keays
RE: How do I calculate tightening torque???
Thanks for that it is just what I need, just two things....
Can you please explain to me what the 'dout' and 'din' are.
Regards,
Biggy
RE: How do I calculate tightening torque???
As an example, let's assume you are using a hex flange nut with an outer diameter of 5 inches. This is your dout. Let's say the piece under your nut has a hole in it of 2.75 inches (to allow a 2.5 inch fastener to easily pass through) - this is your din.
You may contact me directly if you have additional questions.
Cory
cpadfield@omnimetalslab.com
RE: How do I calculate tightening torque???
www.futek.com
Keep the wheels on the ground
Bob
showshine@aol.com
RE: How do I calculate tightening torque???
Rod
RE: How do I calculate tightening torque???
RE: How do I calculate tightening torque???