M22 Grade 4.8 Torque Specification

Torque Values by Surface Condition

Stress area: 303.4 mm² · Proof load: 94,054 N · Clamp load (75%): 70,540 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	310.4	228.9	2747.3	3165.2
Oiled	0.15	232.8	171.7	2060.5	2373.9
Zinc Plated	0.18	279.3	206.0	2472.0	2848.1
Waxed	0.1	155.2	114.5	1373.6	1582.6
MoS₂	0.12	186.2	137.3	1648.0	1898.7
Galvanized	0.25	388.0	286.2	3434.1	3956.5

Stress area: 333.01 mm² · Proof load: 103,233 N · Clamp load (75%): 77,425 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	340.7	251.3	3015.5	3474.2
Oiled	0.15	255.5	188.4	2261.4	2605.4
Zinc Plated	0.18	306.6	226.1	2713.6	3126.5
Waxed	0.1	170.3	125.6	1507.3	1736.6
MoS₂	0.12	204.4	150.8	1809.1	2084.3
Galvanized	0.25	425.8	314.1	3768.6	4342.0

Formula: T = K × D × F

Step 1 — Clamp load: F = 0.75 × 310 MPa × 303.4 mm² = 70,540 N

Step 2 — Torque (dry): T = 0.20 × 0.0220 m × 70,540 N = 310.4 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.

SizeM22

Class4.8

Diameter22 mm

Pitch (coarse)2.5 mm

Tensile420 MPa

Yield340 MPa

Proof310 MPa