M33 Grade 5.6 Torque Specification

Torque Values by Surface Condition

Stress area: 693.55 mm² · Proof load: 194,194 N · Clamp load (75%): 145,646 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	961.3	709.0	8508.2	9802.6
Oiled	0.15	720.9	531.7	6380.5	7351.2
Zinc Plated	0.18	865.1	638.1	7656.8	8821.6
Waxed	0.1	480.6	354.5	4253.7	4900.8
MoS₂	0.12	576.8	425.4	5105.1	5881.7
Galvanized	0.25	1201.6	886.3	10635.1	12253.0

Stress area: 760.85 mm² · Proof load: 213,038 N · Clamp load (75%): 159,778 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	1054.5	777.8	9333.1	10752.9
Oiled	0.15	790.9	583.3	7000.1	8065.0
Zinc Plated	0.18	949.1	700.0	8400.2	9678.2
Waxed	0.1	527.3	388.9	4667.0	5377.0
MoS₂	0.12	632.7	466.7	5599.9	6451.8
Galvanized	0.25	1318.2	972.3	11667.1	13441.9

Formula: T = K × D × F

Step 1 — Clamp load: F = 0.75 × 280 MPa × 693.55 mm² = 145,646 N

Step 2 — Torque (dry): T = 0.20 × 0.0330 m × 145,646 N = 961.3 N·m

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

Moderate-duty industrial applications, machinery guards, medium-strength connections

• 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.

SizeM33

Class5.6

Diameter33 mm

Pitch (coarse)3.5 mm

Tensile500 MPa

Yield300 MPa

Proof280 MPa