M22 Grade 5.8 Torque Specification

Torque Values by Surface Condition

Stress area: 303.4 mm² · Proof load: 115,292 N · Clamp load (75%): 86,469 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	380.5	280.6	3367.7	3880.0
Oiled	0.15	285.3	210.4	2525.1	2909.3
Zinc Plated	0.18	342.4	252.5	3030.5	3491.5
Waxed	0.1	190.2	140.3	1683.4	1939.5
MoS₂	0.12	228.3	168.4	2020.6	2328.0
Galvanized	0.25	475.6	350.8	4209.4	4849.8

Stress area: 333.01 mm² · Proof load: 126,544 N · Clamp load (75%): 94,908 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	417.6	308.0	3696.1	4258.4
Oiled	0.15	313.2	231.0	2772.1	3193.8
Zinc Plated	0.18	375.8	277.2	3326.1	3832.1
Waxed	0.1	208.8	154.0	1848.0	2129.2
MoS₂	0.12	250.6	184.8	2218.0	2555.4
Galvanized	0.25	522.0	385.0	4620.1	5322.9

Formula: T = K × D × F

Step 1 — Clamp load: F = 0.75 × 380 MPa × 303.4 mm² = 86,469 N

Step 2 — Torque (dry): T = 0.20 × 0.0220 m × 86,469 N = 380.5 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.

SizeM22

Class5.8

Diameter22 mm

Pitch (coarse)2.5 mm

Tensile520 MPa

Yield420 MPa

Proof380 MPa