In preparing this guide to torque values the following basic assumptions have been made:
Bolts and nuts are new, standard finish, uncoated and not lubricated*
The load will be 90% of the bolt yield strength
The coefficient of friction (µ) is 0,14
The final tightening sequence is achieved smoothly and slowly until the torque indicates
full torque has been obtained.
The information supplied here is an acceptable guide for normal conditions and includes information on:
* If lubrication has been applied to the bolt and/or the nut (other than the normal protective oil film), multiply the recommended torque by the appropriate factor shown in the Lubrication Factor table. n.b. Antiseize lubricants can reduce torque required by approximately 20%.
|
Surface condition of bolt |
|||||
|
Self |
Electroplated |
||||
|
Zinc |
Cadmium |
Phosphate |
|||
|
Surface |
Self |
1,00 |
1,00 |
0,80 |
0,90 |
| Zinc |
1,15 |
1,20 |
1,35 |
1,15 |
|
| Cadmium |
0,85 |
0,90 |
1,20 |
1,00 |
|
| Phosphate and oil |
0,70 |
0,65 |
0,70 |
0,75 |
|
| Zinc and Wax |
0,60 |
0,55 |
0,65 |
0,55 |
|
| Torque lbf.ft x 1.36 = N•m N•m x 0.737 = lbf.ft Force Pressure |
Flow l/s x 2.119 = cu.ft/min cu.ft/min x 0.472 = l/s Power
|
|
Imperial M = torque lbf.ft
|
Metric M = torque N•m
|
|
M2 = M1x |
L2 |
| L1 |
where L1 in the normal length and L2 is the extended length, M1 is the set torque and M2
the actual torque applied to the nut.
eg. L1=500 L2=650 so
| M2=100x | 650 | =130N•m |
| 500 |
Click here to download a larger, more readable scale image
Click here to download a larger, printable, more readable scale image [PDF format]
