M36 Grade 12.9 Torque Specification

Torque Values by Surface Condition

Stress area: 816.72 mm² · Proof load: 792,218 N · Clamp load (75%): 594,164 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	4278.0	3155.3	37863.5	43623.6
Oiled	0.15	3208.5	2366.5	28397.6	32717.7
Zinc Plated	0.18	3850.2	2839.8	34077.2	39261.3
Waxed	0.1	2139.0	1577.6	18931.8	21811.8
MoS₂	0.12	2566.8	1893.2	22718.1	26174.2
Galvanized	0.25	5347.5	3944.1	47329.4	54529.5

Stress area: 864.95 mm² · Proof load: 839,002 N · Clamp load (75%): 629,251 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	4530.6	3341.6	40099.2	46199.4
Oiled	0.15	3398.0	2506.2	30074.8	34650.1
Zinc Plated	0.18	4077.5	3007.4	36088.9	41579.1
Waxed	0.1	2265.3	1670.8	20049.6	23099.7
MoS₂	0.12	2718.4	2005.0	24059.9	27720.1
Galvanized	0.25	5663.3	4177.0	50124.5	57749.8

Formula: T = K × D × F

Step 1 — Clamp load: F = 0.75 × 970 MPa × 816.72 mm² = 594,164 N

Step 2 — Torque (dry): T = 0.20 × 0.0360 m × 594,164 N = 4278.0 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.

SizeM36

Class12.9

Diameter36 mm

Pitch (coarse)4.0 mm

Tensile1220 MPa

Yield1100 MPa

Proof970 MPa