M30 Grade 5.8 Torque Specification

Torque Values by Surface Condition

Stress area: 560.59 mm² · Proof load: 213,024 N · Clamp load (75%): 159,768 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	958.6	707.0	8484.3	9775.0
Oiled	0.15	719.0	530.3	6363.7	7331.8
Zinc Plated	0.18	862.7	636.3	7635.5	8797.1
Waxed	0.1	479.3	353.5	4242.2	4887.5
MoS₂	0.12	575.2	424.2	5091.0	5865.4
Galvanized	0.25	1198.3	883.8	10605.9	12219.3

Stress area: 621.2 mm² · Proof load: 236,056 N · Clamp load (75%): 177,042 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	1062.3	783.5	9402.2	10832.5
Oiled	0.15	796.7	587.6	7051.4	8124.1
Zinc Plated	0.18	956.0	705.1	8461.3	9748.5
Waxed	0.1	531.1	391.7	4700.6	5415.7
MoS₂	0.12	637.4	470.1	5641.5	6499.7
Galvanized	0.25	1327.8	979.3	11752.0	13539.8

Formula: T = K × D × F

Step 1 — Clamp load: F = 0.75 × 380 MPa × 560.59 mm² = 159,768 N

Step 2 — Torque (dry): T = 0.20 × 0.0300 m × 159,768 N = 958.6 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.

SizeM30

Class5.8

Diameter30 mm

Pitch (coarse)3.5 mm

Tensile520 MPa

Yield420 MPa

Proof380 MPa