9/16-18 UNF Thread Specifications
Complete dimensions for 9/16-18 UNF thread per ASME B1.1. TPI: 18, Pitch: 0.05556" (1.411 mm).
Thread Dimensions
| Designation | 9/16-18 UNF |
| Threads Per Inch (TPI) | 18 |
| Pitch | 0.05556" (1.411 mm) |
| Major Diameter | 0.5625" (14.287 mm) |
| Pitch Diameter | 0.5264" (13.371 mm) |
| Minor Diameter (External) | 0.4943" (12.556 mm) |
| Minor Diameter (Internal) | 0.5024" (12.76 mm) |
| Thread Depth | 0.03007" (0.764 mm) |
| Tensile Stress Area | 0.20138 in² (129.9 mm²) |
Tap Drill Size
Recommended tap drill: 1/2" (0.5" / 12.7 mm)
Calculated minor diameter (internal): 0.5024" (12.76 mm)
Proof Loads by SAE Grade
| Grade | Proof Stress (psi) | Tensile Strength (psi) | Proof Load (lbf) | Tensile Load (lbf) |
|---|---|---|---|---|
| Grade 2 | 55,000 | 74,000 | 11,076 | 14,902 |
| Grade 5 | 85,000 | 120,000 | 17,117 | 24,166 |
| Grade 8 | 120,000 | 150,000 | 24,166 | 30,207 |
Same Size, Different Series
Common Applications
- Industrial and structural applications
- Fine thread applications