converting bar/ MPa/ Psi to N.m

[king92]

Hello friends, i am facing a little problem for the conversion of pressure value to N.m for performing bolt torquing. from the supplier we received the torque value is as 23Mpa/ 230bar but the bolt we were going to do torque is 3/4". As per our company standard only after 1 1/4" bolts only tensioning others are only by using torque wrench. as you well know torque wrench is having the measurement value of Nm not in bar (pressure value). So if anyone know how to calculate Nm value from Bar. please let me know, it will be very helpful.

Share the knowledge and improve our knowledge even further, higher than sun. Thanks

 

[rb1957]

you can't convert torque to pressure (or stress) ... in that N.m are different to N/m2.

torque produces endload (T = Pd/5 is typically used), P/A is stress.

another day in paradise, or is paradise one day closer ?

 

[1503-44]

It's a calculation, not a conversion.

https://www.engineeringtoolbox.com/bolt-torque-load-calculator-d_2065.html

 

[king92]

we have a tensioning tool and with that we received a sheet you can see in the attachment. it's showing bar and torque value corresponds to the bar value. but this value is different from model to model. if the vendor can provide such document. then maybe the have some calculation. that's what i need dears.

 

[dhengr]

Kingsly A:
You’ve got things a little confused. The relationship of those two sets of numbers is not some universally accepted equivalence or conversion factor between the two. Rather, they are a function of the particular machine/tool you are using. More than likely, they design and manufacture the tool and then test it (maybe each tool, separately) against a standard/certified torque measuring device. They record the gage pressure readings at various whole number torque settings, and then tabulate or graph this relationship for your use in the field.

 

[king92]

ok dears thank you. because i couldn't find the solution and after seeing that table maybe have some calculations that i may not know. now i understand clearly thanks for your quick responses.

 

[rb1957]

can you please explain the situation better. professionals probably wouldn't use "pressure" or "bar" for "stress" (like P/A as I suggested in the first response).

I'm thinking the situation is like a machine press, powered by a hand wheel, Apply a torque to the hand wheel, and the press exerts a pressure on some plates.

but I'm guessing and we don't like to guess ...

another day in paradise, or is paradise one day closer ?

 

[LittleInch]

Kingsly,

What you have received is a stress value - 23 MPa. I realise it is the same figure used for pressure, but it is in fact stress.

The sheet you attach is equally confused.

As mr 44 says in the attached link, you can obtain a calculation of torque vs stress in your bolt. However you will note that there are two figures you need to input - type of nut and also lubrication factor. To get a better value you also need pitch angle.

Torque values for bolts can vary by 50% for the same stress value depending on how well or not the nut and bolt is lubricated.

The issue of bolting torque vs bolt stress has been debated many times on this site - please search for it.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[rb1957]

I'm not sure they mean stress when they say "pressure". Sure the units are the same, but not all red things are tomatoes.

another day in paradise, or is paradise one day closer ?

 

[1503-44]

Pressure and stress in this context are simply the difference between the applied load, pressure, and the reaction stress inside whatever element the pressure is being applied to. If the element has an equal area to the pressure, numerically everything is equal. The link I provided has a short description of the calculation procedure. Torque on the bolt acting on an inclined surface of the threads produces pressure on the thread that is resisted by axial force in the bolt, which divided by the bolt's area equals the stress introduced into the bolt.

 

[rb1957]

I think we need the OP to explain his situation better ...

another day in paradise, or is paradise one day closer ?

 

[1503-44]

Not holding my breath.