M27 Grade 10.9 Torque Specification

Torque Values by Surface Condition

Stress area: 459.41 mm² · Proof load: 381,310 N · Clamp load (75%): 285,983 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	1544.3	1139.0	13668.2	15747.5
Oiled	0.15	1158.2	854.2	10250.9	11810.4
Zinc Plated	0.18	1389.9	1025.1	12301.7	14173.1
Waxed	0.1	772.2	569.5	6834.5	7874.3
MoS₂	0.12	926.6	683.4	8201.1	9448.7
Galvanized	0.25	1930.4	1423.8	17085.5	19684.7

Stress area: 496.18 mm² · Proof load: 411,829 N · Clamp load (75%): 308,872 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	1667.9	1230.2	14762.2	17007.9
Oiled	0.15	1250.9	922.6	11071.4	12755.7
Zinc Plated	0.18	1501.1	1107.2	13285.9	15307.0
Waxed	0.1	834.0	615.1	7381.5	8504.5
MoS₂	0.12	1000.7	738.1	8856.9	10204.3
Galvanized	0.25	2084.9	1537.7	18452.9	21260.1

Formula: T = K × D × F

Step 1 — Clamp load: F = 0.75 × 830 MPa × 459.41 mm² = 285,983 N

Step 2 — Torque (dry): T = 0.20 × 0.0270 m × 285,983 N = 1544.3 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.

SizeM27

Class10.9

Diameter27 mm

Pitch (coarse)3.0 mm

Tensile1040 MPa

Yield940 MPa

Proof830 MPa