M22 Grade 12.9 Torque Specification

Torque Values by Surface Condition

Stress area: 303.4 mm² · Proof load: 294,298 N · Clamp load (75%): 220,723 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	971.2	716.3	8595.8	9903.5
Oiled	0.15	728.4	537.2	6446.9	7427.6
Zinc Plated	0.18	874.1	644.7	7736.4	8913.4
Waxed	0.1	485.6	358.2	4297.9	4951.8
MoS₂	0.12	582.7	429.8	5157.3	5941.9
Galvanized	0.25	1214.0	895.4	10744.8	12379.4

Stress area: 333.01 mm² · Proof load: 323,020 N · Clamp load (75%): 242,265 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	1066.0	786.2	9434.9	10870.2
Oiled	0.15	799.5	589.7	7076.2	8152.7
Zinc Plated	0.18	959.4	707.6	8491.4	9783.2
Waxed	0.1	533.0	393.1	4717.4	5435.1
MoS₂	0.12	639.6	471.7	5660.9	6522.1
Galvanized	0.25	1332.5	982.8	11793.6	13587.8

Formula: T = K × D × F

Step 1 — Clamp load: F = 0.75 × 970 MPa × 303.4 mm² = 220,723 N

Step 2 — Torque (dry): T = 0.20 × 0.0220 m × 220,723 N = 971.2 N·m

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

Socket head cap screws, racing/motorsport, aerospace, maximum strength applications — highest standard grade

• 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.

SizeM22

Class12.9

Diameter22 mm

Pitch (coarse)2.5 mm

Tensile1220 MPa

Yield1100 MPa

Proof970 MPa