M48 Grade 12.9 Torque Specification

Torque Values by Surface Condition

Stress area: 1473.19 mm² · Proof load: 1,428,994 N · Clamp load (75%): 1,071,746 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	10288.8	7588.6	91063.6	104917.0
Oiled	0.15	7716.6	5691.5	68297.7	78687.7
Zinc Plated	0.18	9259.9	6829.8	81957.1	94425.1
Waxed	0.1	5144.4	3794.3	45531.8	52458.5
MoS₂	0.12	6173.3	4553.2	54638.3	62950.4
Galvanized	0.25	12860.9	9485.7	113828.6	131145.2

Stress area: 1602.9 mm² · Proof load: 1,554,813 N · Clamp load (75%): 1,166,110 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	11194.7	8256.8	99081.5	114154.6
Oiled	0.15	8396.0	6192.6	74310.9	85615.7
Zinc Plated	0.18	10075.2	7431.1	89173.1	102738.8
Waxed	0.1	5597.3	4128.4	49540.3	57076.8
MoS₂	0.12	6716.8	4954.1	59448.7	68492.6
Galvanized	0.25	13993.3	10320.9	123851.2	142692.5

Formula: T = K × D × F

Step 1 — Clamp load: F = 0.75 × 970 MPa × 1473.19 mm² = 1,071,746 N

Step 2 — Torque (dry): T = 0.20 × 0.0480 m × 1,071,746 N = 10288.8 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.

SizeM48

Class12.9

Diameter48 mm

Pitch (coarse)5.0 mm

Tensile1220 MPa

Yield1100 MPa

Proof970 MPa