M12 Grade 10.9 Torque Specification

Torque Values by Surface Condition

Stress area: 84.27 mm² · Proof load: 69,944 N · Clamp load (75%): 52,458 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	125.9	92.9	1114.3	1283.8
Oiled	0.15	94.4	69.6	835.5	962.6
Zinc Plated	0.18	113.3	83.6	1002.8	1155.3
Waxed	0.1	62.9	46.4	556.7	641.4
MoS₂	0.12	75.5	55.7	668.2	769.9
Galvanized	0.25	157.4	116.1	1393.1	1605.0

Stress area: 92.07 mm² · Proof load: 76,418 N · Clamp load (75%): 57,314 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	137.6	101.5	1217.9	1403.1
Oiled	0.15	103.2	76.1	913.4	1052.4
Zinc Plated	0.18	123.8	91.3	1095.7	1262.4
Waxed	0.1	68.8	50.7	608.9	701.6
MoS₂	0.12	82.5	60.8	730.2	841.3
Galvanized	0.25	171.9	126.8	1521.4	1752.9

Formula: T = K × D × F

Step 1 — Clamp load: F = 0.75 × 830 MPa × 84.27 mm² = 52,458 N

Step 2 — Torque (dry): T = 0.20 × 0.0120 m × 52,458 N = 125.9 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.

SizeM12

Class10.9

Diameter12 mm

Pitch (coarse)1.75 mm

Tensile1040 MPa

Yield940 MPa

Proof830 MPa