1/2-28 UNEF Thread Specifications
Complete dimensions for 1/2-28 UNEF (Unified National Extra Fine) thread per ASME B1.1. TPI: 28, Pitch: 0.03571" (0.907 mm).
Thread Dimensions
| Designation | 1/2-28 UNEF |
| Threads Per Inch (TPI) | 28 |
| Pitch | 0.03571" (0.907 mm) |
| Major Diameter | 0.5" (12.7 mm) |
| Pitch Diameter | 0.4768" (12.111 mm) |
| Minor Diameter (External) | 0.4562" (11.587 mm) |
| Minor Diameter (Internal) | 0.4613" (11.718 mm) |
| Thread Depth | 0.01933" (0.491 mm) |
| Tensile Stress Area | 0.16997 in² (109.7 mm²) |
Tap Drill Size
Recommended tap drill: 15/32" (0.4688" / 11.91 mm)
Calculated minor diameter (internal): 0.4613" (11.72 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 | 9,348 | 12,578 |
| Grade 5 | 85,000 | 120,000 | 14,447 | 20,396 |
| Grade 8 | 120,000 | 150,000 | 20,396 | 25,496 |
Same Size, Different Series
Common Applications
- Precision assemblies
- Thin-wall tubing
- Aerospace fittings