M27 Grade 5.8 Torque Specification

Torque Values by Surface Condition

Stress area: 459.41 mm² · Proof load: 174,576 N · Clamp load (75%): 130,932 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	707.0	521.5	6257.5	7209.4
Oiled	0.15	530.3	391.1	4693.6	5407.6
Zinc Plated	0.18	636.3	469.3	5631.7	6488.5
Waxed	0.1	353.5	260.7	3128.7	3604.7
MoS₂	0.12	424.2	312.9	3754.5	4325.7
Galvanized	0.25	883.8	651.9	7822.3	9012.3

Stress area: 496.18 mm² · Proof load: 188,548 N · Clamp load (75%): 141,411 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	763.6	563.2	6758.4	7786.6
Oiled	0.15	572.7	422.4	5068.8	5839.9
Zinc Plated	0.18	687.3	506.9	6083.1	7008.5
Waxed	0.1	381.8	281.6	3379.2	3893.3
MoS₂	0.12	458.2	338.0	4055.4	4672.4
Galvanized	0.25	954.5	704.0	8448.0	9733.2

Formula: T = K × D × F

Step 1 — Clamp load: F = 0.75 × 380 MPa × 459.41 mm² = 130,932 N

Step 2 — Torque (dry): T = 0.20 × 0.0270 m × 130,932 N = 707.0 N·m

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

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.

SizeM27

Class5.8

Diameter27 mm

Pitch (coarse)3.0 mm

Tensile520 MPa

Yield420 MPa

Proof380 MPa