#6" Grade 8 Torque Specification

Torque Values by Surface Condition

Stress area: 0.00909 in² · Proof load: 1,091 lbs · Clamp load (75%): 818 lbs

Surface Condition	K Factor	ft·lbs	N·m	in·lbs	kgf·cm
Plain/Dry	0.2	1.9	2.6	22.8	26.5
Oiled	0.15	1.4	1.9	16.8	19.4
Zinc Plated	0.18	1.7	2.3	20.4	23.5
Waxed	0.1	0.9	1.2	10.8	12.2
MoS₂	0.12	1.1	1.5	13.2	15.3
Galvanized	0.25	2.4	3.3	28.8	33.7

Stress area: 0.01015 in² · Proof load: 1,218 lbs · Clamp load (75%): 913 lbs

Surface Condition	K Factor	ft·lbs	N·m	in·lbs	kgf·cm
Plain/Dry	0.2	2.1	2.8	25.2	28.6
Oiled	0.15	1.6	2.2	19.2	22.4
Zinc Plated	0.18	1.9	2.6	22.8	26.5
Waxed	0.1	1.1	1.5	13.2	15.3
MoS₂	0.12	1.3	1.8	15.6	18.4
Galvanized	0.25	2.6	3.5	31.2	35.7

Formula: T = K × D × F

Step 1 — Clamp load: F = 0.75 × 120,000 psi × 0.00909 in² = 818 lbs

Step 2 — Torque (dry): T = 0.20 × 0.138 in × 818 lbs ÷ 12 = 1.9 ft·lbs

Proof stress per SAE J429 Table 3. Stress area per ASME B1.1. K-factor per VDI 2230.

High-strength applications, heavy equipment, critical joints, suspension components, trailer hitches. Equivalent to ISO 10.9.

• Torque values are for standard hex bolts with unified threads per ASME B1.1. 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.
• Re-used bolts may have altered friction characteristics. Inspect threads before reuse.

Size#6"

Grade8

Diameter0.138" (3.51 mm)

TPI (UNC)32

Tensile150,000 psi

Yield130,000 psi

Proof120,000 psi