M48 Grade 10.9 Torque Specification

Torque Values by Surface Condition

Stress area: 1473.19 mm² · Proof load: 1,222,748 N · Clamp load (75%): 917,061 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	8803.8	6493.3	77920.2	89774.1
Oiled	0.15	6602.8	4870.0	58439.7	67330.1
Zinc Plated	0.18	7923.4	5844.0	70128.0	80796.5
Waxed	0.1	4401.9	3246.7	38960.1	44887.1
MoS₂	0.12	5282.3	3896.0	46752.3	53864.7
Galvanized	0.25	11004.7	8116.6	97399.8	112217.1

Stress area: 1602.9 mm² · Proof load: 1,330,407 N · Clamp load (75%): 997,805 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	9578.9	7065.0	84780.4	97678.0
Oiled	0.15	7184.2	5298.8	63585.6	73258.7
Zinc Plated	0.18	8621.0	6358.5	76302.3	87910.1
Waxed	0.1	4789.5	3532.6	42390.7	48839.5
MoS₂	0.12	5747.4	4239.1	50868.8	58607.4
Galvanized	0.25	11973.7	8831.3	105976.2	122098.2

Formula: T = K × D × F

Step 1 — Clamp load: F = 0.75 × 830 MPa × 1473.19 mm² = 917,061 N

Step 2 — Torque (dry): T = 0.20 × 0.0480 m × 917,061 N = 8803.8 N·m

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

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.

SizeM48

Class10.9

Diameter48 mm

Pitch (coarse)5.0 mm

Tensile1040 MPa

Yield940 MPa

Proof830 MPa