M7 Grade 10.9 Torque Specification

Torque Values by Surface Condition

Stress area: 28.86 mm² · Proof load: 23,954 N · Clamp load (75%): 17,965 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	25.2	18.6	223.0	257.0
Oiled	0.15	18.9	13.9	167.3	192.7
Zinc Plated	0.18	22.6	16.7	200.0	230.5
Waxed	0.1	12.6	9.3	111.5	128.5
MoS₂	0.12	15.1	11.1	133.6	154.0
Galvanized	0.25	31.4	23.2	277.9	320.2

Stress area: 31.23 mm² · Proof load: 25,921 N · Clamp load (75%): 19,441 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	27.2	20.1	240.7	277.4
Oiled	0.15	20.4	15.0	180.6	208.0
Zinc Plated	0.18	24.5	18.1	216.8	249.8
Waxed	0.1	13.6	10.0	120.4	138.7
MoS₂	0.12	16.3	12.0	144.3	166.2
Galvanized	0.25	34.0	25.1	300.9	346.7

Formula: T = K × D × F

Step 1 — Clamp load: F = 0.75 × 830 MPa × 28.86 mm² = 17,965 N

Step 2 — Torque (dry): T = 0.20 × 0.0070 m × 17,965 N = 25.2 N·m

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

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.

SizeM7

Class10.9

Diameter7 mm

Pitch (coarse)1.0 mm

Tensile1040 MPa

Yield940 MPa

Proof830 MPa