In a bolted joint, the nut or screw must be secured after pre-tightening so that the joint cannot loosen as the parts move relative to each other.
When installing a bolted joint, ensure that the screw head, washer, and nut are seated firmly against their washer. After pre-tightening, perform the final tightening of the bolted joint to the tightening torque permitted for the fastener and nut. Tightening can be done manually with a torque wrench or mechanically to the specified tightening torque. In mechanical tightening, the coefficient of friction must be taken into account. Recommended tightening torques have been provided for fasteners and can be found in the table below.
| Thread | N/m 4.6 | N/m 5.8 | N/m 8.8 | N/m 10.9 | N/m 12.9 |
| M3 | 0,5 | ||||
| M4 | 1,2 | ||||
| M5 | 2,4 | 4,1 | 6,5 | ||
| M6 | 4,2 | 6,9 | 11 | ||
| M7 | 4,2 | 6,9 | 11 | ||
| M8 | 10 | 17 | 27 | ||
| M10 | 20 | 33 | 53 | 74 | 89 |
| M12 | 34 | 57 | 91 | 128 | 154 |
| M14 |
The values require the use of a torque wrench. When using a powered nutrunner, the tightening torque is approximately 0.93 x the table value. By using the correction factor, the tightening torque corresponding to the friction conditions can be calculated from the table values.
| Coating | Nut / Threaded hole | Lubrication | Factor |
| Electrogalvanized (ZN) | Electrogalvanized (ZN) | Dry | 0.89 |
| Electrogalvanized (ZN) | Electrogalvanized (ZN) | Oiled | 0.74 |
| Uncoated (ST) | Uncoated | Dry | 0.89 |
| Uncoated (ST) | Uncoated | Oiled | 0.93 |
| Hot-dip galvanized (HDG) | Uncoated | Dry | 1.13 |
| Hot-dip galvanized (HDG) | Uncoated | Oiled | 0.89 |