M30 Grade 10.9 Torque Specification

Torque Values by Surface Condition

Stress area: 560.59 mm² · Proof load: 465,290 N · Clamp load (75%): 348,967 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	2093.8	1544.3	18531.7	21350.9
Oiled	0.15	1570.4	1158.3	13899.2	16013.7
Zinc Plated	0.18	1884.4	1389.9	16678.4	19215.6
Waxed	0.1	1046.9	772.2	9265.9	10675.4
MoS₂	0.12	1256.3	926.6	11119.2	12810.7
Galvanized	0.25	2617.3	1930.4	23165.1	26689.1

Stress area: 621.2 mm² · Proof load: 515,596 N · Clamp load (75%): 386,697 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	2320.2	1711.3	20535.5	23659.5
Oiled	0.15	1740.1	1283.4	15401.2	17744.1
Zinc Plated	0.18	2088.2	1540.2	18482.1	21293.8
Waxed	0.1	1160.1	855.6	10267.8	11829.8
MoS₂	0.12	1392.1	1026.8	12321.1	14195.5
Galvanized	0.25	2900.2	2139.1	25668.9	29573.9

Formula: T = K × D × F

Step 1 — Clamp load: F = 0.75 × 830 MPa × 560.59 mm² = 348,967 N

Step 2 — Torque (dry): T = 0.20 × 0.0300 m × 348,967 N = 2093.8 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.

SizeM30

Class10.9

Diameter30 mm

Pitch (coarse)3.5 mm

Tensile1040 MPa

Yield940 MPa

Proof830 MPa