13/16-20 UNEF Thread Specifications
Complete dimensions for 13/16-20 UNEF (Unified National Extra Fine) thread per ASME B1.1. TPI: 20, Pitch: 0.05" (1.27 mm).
Thread Dimensions
| Designation | 13/16-20 UNEF |
| Threads Per Inch (TPI) | 20 |
| Pitch | 0.05" (1.27 mm) |
| Major Diameter | 0.8125" (20.637 mm) |
| Pitch Diameter | 0.78" (19.813 mm) |
| Minor Diameter (External) | 0.7512" (19.079 mm) |
| Minor Diameter (Internal) | 0.7584" (19.263 mm) |
| Thread Depth | 0.02706" (0.687 mm) |
| Tensile Stress Area | 0.45818 in² (295.6 mm²) |
Tap Drill Size
Recommended tap drill: 49/64" (0.7656" / 19.45 mm)
Calculated minor diameter (internal): 0.7584" (19.26 mm)
Proof Loads by SAE Grade
| Grade | Proof Stress (psi) | Tensile Strength (psi) | Proof Load (lbf) | Tensile Load (lbf) |
|---|---|---|---|---|
| Grade 2 | 33,000 | 60,000 | 15,120 | 27,491 |
| Grade 5 | 85,000 | 120,000 | 38,945 | 54,981 |
| Grade 8 | 120,000 | 150,000 | 54,981 | 68,727 |
Common Applications
- Precision assemblies
- Thin-wall tubing
- Aerospace fittings