M18 Grade 10.9 Torque Specification

Torque Values by Surface Condition

Stress area: 192.47 mm² · Proof load: 159,750 N · Clamp load (75%): 119,813 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	431.3	318.1	3817.3	4398.1
Oiled	0.15	323.5	238.6	2863.2	3298.8
Zinc Plated	0.18	388.2	286.3	3435.9	3958.6
Waxed	0.1	215.7	159.1	1909.1	2199.5
MoS₂	0.12	258.8	190.9	2290.6	2639.0
Galvanized	0.25	539.2	397.7	4772.3	5498.3

Stress area: 216.23 mm² · Proof load: 179,471 N · Clamp load (75%): 134,603 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	484.6	357.4	4289.1	4941.6
Oiled	0.15	363.4	268.0	3216.4	3705.7
Zinc Plated	0.18	436.1	321.7	3859.8	4447.0
Waxed	0.1	242.3	178.7	2144.5	2470.8
MoS₂	0.12	290.7	214.4	2572.9	2964.3
Galvanized	0.25	605.7	446.7	5360.9	6176.4

Formula: T = K × D × F

Step 1 — Clamp load: F = 0.75 × 830 MPa × 192.47 mm² = 119,813 N

Step 2 — Torque (dry): T = 0.20 × 0.0180 m × 119,813 N = 431.3 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.

SizeM18

Class10.9

Diameter18 mm

Pitch (coarse)2.5 mm

Tensile1040 MPa

Yield940 MPa

Proof830 MPa