M48 Grade 5.8 Torque Specification

Torque Values by Surface Condition

Stress area: 1473.19 mm² · Proof load: 559,812 N · Clamp load (75%): 419,859 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	4030.6	2972.8	35673.8	41100.8
Oiled	0.15	3023.0	2229.6	26755.8	30826.1
Zinc Plated	0.18	3627.6	2675.6	32107.0	36991.4
Waxed	0.1	2015.3	1486.4	17836.9	20550.4
MoS₂	0.12	2418.4	1783.7	21404.7	24660.9
Galvanized	0.25	5038.3	3716.1	44592.7	51376.6

Stress area: 1602.9 mm² · Proof load: 609,102 N · Clamp load (75%): 456,826 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	4385.5	3234.6	38815.0	44719.8
Oiled	0.15	3289.2	2426.0	29111.9	33540.6
Zinc Plated	0.18	3947.0	2911.2	34933.9	40248.3
Waxed	0.1	2192.8	1617.3	19407.9	22360.4
MoS₂	0.12	2631.3	1940.7	23289.0	26831.9
Galvanized	0.25	5481.9	4043.2	48518.9	55900.0

Formula: T = K × D × F

Step 1 — Clamp load: F = 0.75 × 380 MPa × 1473.19 mm² = 419,859 N

Step 2 — Torque (dry): T = 0.20 × 0.0480 m × 419,859 N = 4030.6 N·m

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

General industrial fastening, equipment mounting, moderate structural loads

• 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

Class5.8

Diameter48 mm

Pitch (coarse)5.0 mm

Tensile520 MPa

Yield420 MPa

Proof380 MPa