Stress area: 0.226 in² · Proof load: 27,120 lbs · Clamp load (75%): 20,340 lbs
| Surface Condition | K Factor | ft·lbs | N·m | in·lbs | kgf·cm |
|---|---|---|---|---|---|
| Plain/Dry | 0.2 | 211.9 | 287.3 | 2542.5 | 2929.3 |
| Oiled | 0.15 | 158.9 | 215.4 | 1906.9 | 2197.0 |
| Zinc Plated | 0.18 | 190.7 | 258.6 | 2288.2 | 2636.3 |
| Waxed | 0.1 | 105.9 | 143.6 | 1271.2 | 1464.6 |
| MoS₂ | 0.12 | 127.1 | 172.3 | 1525.5 | 1757.6 |
| Galvanized | 0.25 | 264.8 | 359.0 | 3178.1 | 3661.6 |
Stress area: 0.256 in² · Proof load: 30,720 lbs · Clamp load (75%): 23,040 lbs
| Surface Condition | K Factor | ft·lbs | N·m | in·lbs | kgf·cm |
|---|---|---|---|---|---|
| Plain/Dry | 0.2 | 240.0 | 325.4 | 2880.0 | 3318.1 |
| Oiled | 0.15 | 180.0 | 244.0 | 2160.0 | 2488.6 |
| Zinc Plated | 0.18 | 216.0 | 292.9 | 2592.0 | 2986.3 |
| Waxed | 0.1 | 120.0 | 162.7 | 1440.0 | 1659.1 |
| MoS₂ | 0.12 | 144.0 | 195.2 | 1728.0 | 1990.9 |
| Galvanized | 0.25 | 300.0 | 406.7 | 3600.0 | 4147.6 |
UNC thread, ft·lbs. Values from the table above.
Same bolt, same target clamp load: thread friction alone moves the required torque from 105.9 ft·lbs (waxed) to 264.8 ft·lbs (hot-dip galvanized), 2.5× as much. Match the row to the fastener's actual finish and lubrication.
Formula: T = K × D × F
Step 1 — Clamp load: F = 0.75 × 120,000 psi × 0.226 in² = 20,340 lbs
Step 2 — Torque (dry): T = 0.20 × 0.625 in × 20,340 lbs ÷ 12 = 211.9 ft·lbs
Proof stress per SAE J429 Table 3. Stress area per ASME B1.1. Typical K-factor, consistent with VDI 2230 friction values.
High-strength applications, heavy equipment, critical joints, suspension components, trailer hitches. Equivalent to ISO 10.9.