M27 Grade 12.9 Torque Specification

Torque Values by Surface Condition

Stress area: 459.41 mm² · Proof load: 445,628 N · Clamp load (75%): 334,221 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	1804.8	1331.2	15973.8	18403.9
Oiled	0.15	1353.6	998.4	11980.4	13802.9
Zinc Plated	0.18	1624.3	1198.0	14376.3	16563.3
Waxed	0.1	902.4	665.6	7986.9	9202.0
MoS₂	0.12	1082.9	798.7	9584.5	11042.5
Galvanized	0.25	2256.0	1663.9	19967.3	23004.9

Stress area: 496.18 mm² · Proof load: 481,295 N · Clamp load (75%): 360,971 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	1949.2	1437.7	17251.9	19876.4
Oiled	0.15	1461.9	1078.2	12938.9	14907.3
Zinc Plated	0.18	1754.3	1293.9	15526.9	17888.9
Waxed	0.1	974.6	718.8	8625.9	9938.2
MoS₂	0.12	1169.5	862.6	10351.0	11925.6
Galvanized	0.25	2436.6	1797.1	21565.7	24846.5

Formula: T = K × D × F

Step 1 — Clamp load: F = 0.75 × 970 MPa × 459.41 mm² = 334,221 N

Step 2 — Torque (dry): T = 0.20 × 0.0270 m × 334,221 N = 1804.8 N·m

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

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.

SizeM27

Class12.9

Diameter27 mm

Pitch (coarse)3.0 mm

Tensile1220 MPa

Yield1100 MPa

Proof970 MPa