M30 Grade 12.9 Torque Specification

Torque Values by Surface Condition

Stress area: 560.59 mm² · Proof load: 543,772 N · Clamp load (75%): 407,829 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	2447.0	1804.8	21657.8	24952.5
Oiled	0.15	1835.2	1353.6	16242.9	18713.9
Zinc Plated	0.18	2202.3	1624.3	19492.0	22457.3
Waxed	0.1	1223.5	902.4	10828.9	12476.3
MoS₂	0.12	1468.2	1082.9	12994.7	14971.5
Galvanized	0.25	3058.7	2256.0	27071.8	31190.2

Stress area: 621.2 mm² · Proof load: 602,564 N · Clamp load (75%): 451,923 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	2711.5	1999.9	23998.8	27649.7
Oiled	0.15	2033.7	1500.0	17999.8	20738.0
Zinc Plated	0.18	2440.4	1799.9	21599.4	24885.2
Waxed	0.1	1355.8	1000.0	11999.8	13825.4
MoS₂	0.12	1626.9	1199.9	14399.3	16589.8
Galvanized	0.25	3389.4	2499.9	29998.7	34562.4

Formula: T = K × D × F

Step 1 — Clamp load: F = 0.75 × 970 MPa × 560.59 mm² = 407,829 N

Step 2 — Torque (dry): T = 0.20 × 0.0300 m × 407,829 N = 2447.0 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.

SizeM30

Class12.9

Diameter30 mm

Pitch (coarse)3.5 mm

Tensile1220 MPa

Yield1100 MPa

Proof970 MPa