7/8-9 UNC Thread Specifications
Complete dimensions for 7/8-9 UNC (Unified National Coarse) thread per ASME B1.1. TPI: 9, Pitch: 0.11111" (2.822 mm).
Thread Dimensions
| Designation | 7/8-9 UNC |
| Threads Per Inch (TPI) | 9 |
| Pitch | 0.11111" (2.822 mm) |
| Major Diameter | 0.875" (22.225 mm) |
| Pitch Diameter | 0.8028" (20.392 mm) |
| Minor Diameter (External) | 0.7387" (18.762 mm) |
| Minor Diameter (Internal) | 0.7547" (19.17 mm) |
| Thread Depth | 0.06014" (1.528 mm) |
| Tensile Stress Area | 0.46173 in² (297.9 mm²) |
Tap Drill Size
Recommended tap drill: 3/4" (0.75" / 19.05 mm)
Calculated minor diameter (internal): 0.7547" (19.17 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 | 25,395 | 34,168 |
| Grade 5 | 85,000 | 120,000 | 39,247 | 55,408 |
| Grade 8 | 120,000 | 150,000 | 55,408 | 69,260 |
Same Size, Different Series
Common Applications
- Heavy structural, industrial equipment, anchor bolts
- Coarse thread applications