1" Grade 8 Torque Specification

Torque Values by Surface Condition

Stress area: 0.606 in² · Proof load: 72,720 lbs · Clamp load (75%): 54,540 lbs

Surface Condition	K Factor	ft·lbs	N·m	in·lbs	kgf·cm
Plain/Dry	0.2	909.0	1232.4	10908.0	12567.0
Oiled	0.15	681.8	924.4	8181.6	9426.3
Zinc Plated	0.18	818.1	1109.2	9817.2	11310.7
Waxed	0.1	454.5	616.2	5454.0	6283.5
MoS₂	0.12	545.4	739.5	6544.8	7540.8
Galvanized	0.25	1136.2	1540.5	13634.4	15708.8

Stress area: 0.663 in² · Proof load: 79,560 lbs · Clamp load (75%): 59,670 lbs

Surface Condition	K Factor	ft·lbs	N·m	in·lbs	kgf·cm
Plain/Dry	0.2	994.5	1348.4	11934.0	13749.9
Oiled	0.15	745.9	1011.3	8950.8	10312.4
Zinc Plated	0.18	895.1	1213.6	10741.2	12375.3
Waxed	0.1	497.2	674.1	5966.4	6873.9
MoS₂	0.12	596.7	809.0	7160.4	8249.5
Galvanized	0.25	1243.1	1685.4	14917.2	17186.4

Formula: T = K × D × F

Step 1 — Clamp load: F = 0.75 × 120,000 psi × 0.606 in² = 54,540 lbs

Step 2 — Torque (dry): T = 0.20 × 1.0 in × 54,540 lbs ÷ 12 = 909.0 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.

Size1"

Grade8

Diameter1.0" (25.40 mm)

TPI (UNC)8

Tensile150,000 psi

Yield130,000 psi

Proof120,000 psi