Bolt Torque Specification Chart
Recommended tightening torque values for standard bolt sizes in various materials and grades.
The following table provides recommended tightening torque values for standard metric hex bolts in dry condition. Values are based on 75% of proof load and assume clean, unlubricated threads. For lubricated or plated bolts, reduce torque values by approximately 15-25%. Always verify with project-specific engineering requirements.
Metric Hex Bolt Torque Values (Dry)
| Bolt Size | Grade 4.6 (Nm) | Grade 8.8 (Nm) | Grade 10.9 (Nm) | Grade 12.9 (Nm) |
|---|---|---|---|---|
| M6 | 4.9 | 10.8 | 15.2 | 17.8 |
| M8 | 12 | 26 | 37 | 43 |
| M10 | 24 | 52 | 73 | 86 |
| M12 | 41 | 90 | 127 | 149 |
| M16 | 100 | 220 | 310 | 363 |
| M20 | 196 | 430 | 610 | 714 |
| M24 | 340 | 744 | 1050 | 1230 |
| M30 | 670 | 1470 | 2080 | 2430 |
Key Notes
- —Grade 4.6: Mild steel, general purpose applications
- —Grade 8.8: High tensile, structural and automotive applications
- —Grade 10.9: Alloy steel, high-stress applications (e.g., engine components)
- —Grade 12.9: Highest common grade, critical structural joints
- —For stainless steel bolts (A2-70, A4-80), torque values are approximately 70-80% of Grade 8.8 values
Disclaimer: Values provided in this reference are approximate and intended for general guidance only. Actual specifications may vary based on manufacturing tolerances, surface conditions, and environmental factors. Always consult relevant IS/ISO/ASTM standards and project engineering specifications for critical applications. Pankaj Fasteners Pvt. Ltd. assumes no liability for the use of these reference values in design or construction.
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