M14 Grade 6.8 Torque Specification

Torque Values by Surface Condition

Stress area: 115.44 mm² · Proof load: 50,794 N · Clamp load (75%): 38,095 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	106.7	78.7	944.4	1088.0
Oiled	0.15	80.0	59.0	708.1	815.8
Zinc Plated	0.18	96.0	70.8	849.7	978.9
Waxed	0.1	53.3	39.3	471.7	543.5
MoS₂	0.12	64.0	47.2	566.4	652.6
Galvanized	0.25	133.3	98.3	1179.8	1359.3

Stress area: 124.55 mm² · Proof load: 54,802 N · Clamp load (75%): 41,102 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	115.1	84.9	1018.7	1173.7
Oiled	0.15	86.3	63.7	763.8	880.0
Zinc Plated	0.18	103.6	76.4	916.9	1056.4
Waxed	0.1	57.5	42.4	508.9	586.3
MoS₂	0.12	69.1	51.0	611.6	704.6
Galvanized	0.25	143.9	106.1	1273.6	1467.4

Formula: T = K × D × F

Step 1 — Clamp load: F = 0.75 × 440 MPa × 115.44 mm² = 38,095 N

Step 2 — Torque (dry): T = 0.20 × 0.0140 m × 38,095 N = 106.7 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.

SizeM14

Class6.8

Diameter14 mm

Pitch (coarse)2.0 mm

Tensile600 MPa

Yield480 MPa

Proof440 MPa