1-9/16-18 UNEF Thread Specifications
Complete dimensions for 1-9/16-18 UNEF (Unified National Extra Fine) thread per ASME B1.1. TPI: 18, Pitch: 0.05556" (1.411 mm).
Thread Dimensions
| Designation | 1-9/16-18 UNEF |
| Threads Per Inch (TPI) | 18 |
| Pitch | 0.05556" (1.411 mm) |
| Major Diameter | 1.5625" (39.688 mm) |
| Pitch Diameter | 1.5264" (38.771 mm) |
| Minor Diameter (External) | 1.4943" (37.956 mm) |
| Minor Diameter (Internal) | 1.5024" (38.16 mm) |
| Thread Depth | 0.03007" (0.764 mm) |
| Tensile Stress Area | 1.78693 in² (1152.9 mm²) |
Tap Drill Size
Recommended tap drill: 1-1/2" (1.5" / 38.1 mm)
Calculated minor diameter (internal): 1.5024" (38.16 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 | 98,281 | 132,233 |
| Grade 5 | 85,000 | 120,000 | 151,889 | 214,432 |
| Grade 8 | 120,000 | 150,000 | 214,432 | 268,040 |
Common Applications
- Precision assemblies
- Thin-wall tubing
- Aerospace fittings