M64 Grade 10.9 Torque Specification

Torque Values by Surface Condition

Stress area: 2676.0 mm² · Proof load: 2,221,080 N · Clamp load (75%): 1,665,810 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	21322.4	15726.6	188719.2	217428.8
Oiled	0.15	15991.8	11794.9	141539.4	163071.6
Zinc Plated	0.18	19190.1	14153.9	169846.8	195685.3
Waxed	0.1	10661.2	7863.3	94359.6	108714.4
MoS₂	0.12	12793.4	9435.9	113231.2	130456.9
Galvanized	0.25	26653.0	19658.2	235899.0	271786.0

Stress area: 2809.0 mm² · Proof load: 2,331,470 N · Clamp load (75%): 1,748,602 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	22382.1	16508.2	198098.4	228234.8
Oiled	0.15	16786.6	12381.2	148574.0	171176.3
Zinc Plated	0.18	20143.9	14857.4	178288.6	205411.4
Waxed	0.1	11191.1	8254.1	99049.6	114117.9
MoS₂	0.12	13429.3	9904.9	118859.4	136941.3
Galvanized	0.25	27977.6	20635.2	247622.7	285293.2

Formula: T = K × D × F

Step 1 — Clamp load: F = 0.75 × 830 MPa × 2676.0 mm² = 1,665,810 N

Step 2 — Torque (dry): T = 0.20 × 0.0640 m × 1,665,810 N = 21322.4 N·m

Proof stress per ISO 898-1:2013 Table 4. Stress area per ISO 898-1 Annex A. K-factor per VDI 2230.

Structural steel (equivalent to ASTM A490), heavy machinery, high-strength critical joints, pressure vessels

• Torque values are for standard hex bolts with ISO metric threads. Socket head cap screws may have different requirements.
• Lubrication reduces required torque significantly — using dry torque values on lubricated bolts risks exceeding yield strength.
• For critical or safety-related applications, always consult the manufacturer's specifications or applicable design standard (e.g., VDI 2230).
• Re-used bolts may have altered friction characteristics. Inspect threads before reuse.

SizeM64

Class10.9

Diameter64 mm

Pitch (coarse)6.0 mm

Tensile1040 MPa

Yield940 MPa

Proof830 MPa