M18 Grade 12.9 Torque Specification

Torque Values by Surface Condition

Stress area: 192.47 mm² · Proof load: 186,696 N · Clamp load (75%): 140,022 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	504.1	371.8	4461.7	5140.4
Oiled	0.15	378.1	278.9	3346.5	3855.6
Zinc Plated	0.18	453.7	334.6	4015.6	4626.5
Waxed	0.1	252.0	185.9	2230.4	2569.7
MoS₂	0.12	302.4	223.0	2676.5	3083.6
Galvanized	0.25	630.1	464.7	5576.9	6425.3

Stress area: 216.23 mm² · Proof load: 209,743 N · Clamp load (75%): 157,307 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	566.3	417.7	5012.2	5774.7
Oiled	0.15	424.7	313.2	3758.9	4330.8
Zinc Plated	0.18	509.7	375.9	4511.2	5197.5
Waxed	0.1	283.2	208.9	2506.5	2887.8
MoS₂	0.12	339.8	250.6	3007.5	3465.0
Galvanized	0.25	707.9	522.1	6265.4	7218.6

Formula: T = K × D × F

Step 1 — Clamp load: F = 0.75 × 970 MPa × 192.47 mm² = 140,022 N

Step 2 — Torque (dry): T = 0.20 × 0.0180 m × 140,022 N = 504.1 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.

SizeM18

Class12.9

Diameter18 mm

Pitch (coarse)2.5 mm

Tensile1220 MPa

Yield1100 MPa

Proof970 MPa