## 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???