M16 Grade 6.8 Torque Specification

Torque Values by Surface Condition

Stress area: 156.67 mm² · Proof load: 68,935 N · Clamp load (75%): 51,701 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	165.4	122.0	1463.9	1686.6
Oiled	0.15	124.1	91.5	1098.4	1265.5
Zinc Plated	0.18	148.9	109.8	1317.9	1518.4
Waxed	0.1	82.7	61.0	732.0	843.3
MoS₂	0.12	99.3	73.2	878.9	1012.6
Galvanized	0.25	206.8	152.5	1830.3	2108.8

Stress area: 167.25 mm² · Proof load: 73,590 N · Clamp load (75%): 55,192 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	176.6	130.3	1563.0	1800.8
Oiled	0.15	132.5	97.7	1172.7	1351.1
Zinc Plated	0.18	159.0	117.3	1407.3	1621.4
Waxed	0.1	88.3	65.1	781.5	900.4
MoS₂	0.12	106.0	78.2	938.2	1080.9
Galvanized	0.25	220.8	162.9	1954.2	2251.5

Formula: T = K × D × F

Step 1 — Clamp load: F = 0.75 × 440 MPa × 156.67 mm² = 51,701 N

Step 2 — Torque (dry): T = 0.20 × 0.0160 m × 51,701 N = 165.4 N·m

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

Industrial machinery, agricultural equipment, elevated load requirements

• 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.

SizeM16

Class6.8

Diameter16 mm

Pitch (coarse)2.0 mm

Tensile600 MPa

Yield480 MPa

Proof440 MPa