M30 Grade 4.8 Torque Specification

Torque Values by Surface Condition

Stress area: 560.59 mm² · Proof load: 173,783 N · Clamp load (75%): 130,337 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	782.0	576.8	6921.3	7974.2
Oiled	0.15	586.5	432.6	5191.0	5980.7
Zinc Plated	0.18	703.8	519.1	6229.2	7176.8
Waxed	0.1	391.0	288.4	3460.6	3987.1
MoS₂	0.12	469.2	346.1	4152.8	4784.5
Galvanized	0.25	977.5	721.0	8651.6	9967.8

Stress area: 621.2 mm² · Proof load: 192,572 N · Clamp load (75%): 144,429 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	866.6	639.2	7670.1	8836.9
Oiled	0.15	649.9	479.3	5752.1	6627.2
Zinc Plated	0.18	779.9	575.2	6902.7	7952.8
Waxed	0.1	433.3	319.6	3835.0	4418.4
MoS₂	0.12	519.9	383.5	4601.5	5301.5
Galvanized	0.25	1083.2	798.9	9587.1	11045.6

Formula: T = K × D × F

Step 1 — Clamp load: F = 0.75 × 310 MPa × 560.59 mm² = 130,337 N

Step 2 — Torque (dry): T = 0.20 × 0.0300 m × 130,337 N = 782.0 N·m

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

Light structural connections, furniture assembly, non-load-bearing joints

• 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

Class4.8

Diameter30 mm

Pitch (coarse)3.5 mm

Tensile420 MPa

Yield340 MPa

Proof310 MPa