Unified Inch (UNC / UNF / UN)
8-UN Constant Pitch Series
8 threads per inch across all diameters, used on large bolts and studs for high-pressure flanges.
- Standard
- ANSI/ASME B1.1
- Flank angle
- 60°
- Sizes listed
- 32
- Range
- 1 1/16" - 8-UN – 4" - 8-UN
| Nominal Diameter | Major Diameter Inch | Major Diameter mm | Tapping Drill Size mm | TPI | Pitch mm |
|---|---|---|---|---|---|
| 1 1/16" - 8-UN | 1.0625 | 26.987 | 24.000 | 8 | 3.175 |
| 1 1/8" - 8-UN | 1.1250 | 28.575 | 25.500 | 8 | 3.175 |
| 1 3/16" - 8-UN | 1.1875 | 30.162 | 27.200 | 8 | 3.175 |
| 1 1/4" - 8-UN | 1.2500 | 31.750 | 28.800 | 8 | 3.175 |
| 1 5/16" - 8-UN | 1.3125 | 33.337 | 30.300 | 8 | 3.175 |
| 1 3/8" - 8-UN | 1.3750 | 34.925 | 31.900 | 8 | 3.175 |
| 1 7/16" - 8-UN | 1.4375 | 36.512 | 33.500 | 8 | 3.175 |
| 1 1/2" - 8-UN | 1.5000 | 38.100 | 35.100 | 8 | 3.175 |
| 1 9/16" - 8-UN | 1.5625 | 39.688 | 36.700 | 8 | 3.175 |
| 1 5/8" - 8-UN | 1.6250 | 41.275 | 38.300 | 8 | 3.175 |
| 1 11/16" - 8-UN | 1.6875 | 42.862 | 39.900 | 8 | 3.175 |
| 1 3/4" - 8-UN | 1.7500 | 44.450 | 41.400 | 8 | 3.175 |
| 1 13/16" - 8-UN | 1.8125 | 46.037 | 43.000 | 8 | 3.175 |
| 1 7/8" - 8-UN | 1.8750 | 47.625 | 44.600 | 8 | 3.175 |
| 1 15/16" - 8-UN | 1.9375 | 49.212 | 46.200 | 8 | 3.175 |
| 2" - 8-UN | 2.0000 | 50.800 | 47.800 | 8 | 3.175 |
| 2 1/8" - 8-UN | 2.1250 | 53.975 | 51.000 | 8 | 3.175 |
| 2 1/4" - 8-UN | 2.2500 | 57.150 | 54.100 | 8 | 3.175 |
| 2 3/8" - 8-UN | 2.3750 | 60.325 | 57.300 | 8 | 3.175 |
| 2 1/2" - 8-UN | 2.5000 | 63.500 | 60.500 | 8 | 3.175 |
| 2 5/8" - 8-UN | 2.6250 | 66.675 | 64.700 | 8 | 3.175 |
| 2 3/4" - 8-UN | 2.7500 | 69.850 | 66.800 | 8 | 3.175 |
| 2 7/8" - 8-UN | 2.8750 | 73.025 | 70.000 | 8 | 3.175 |
| 3" - 8-UN | 3.0000 | 76.200 | 73.200 | 8 | 3.175 |
| 3 1/8" - 8-UN | 3.1250 | 79.375 | 76.400 | 8 | 3.175 |
| 3 1/4" - 8-UN | 3.2500 | 82.550 | 79.500 | 8 | 3.175 |
| 3 3/8" - 8-UN | 3.3750 | 85.725 | 82.700 | 8 | 3.175 |
| 3 1/2" - 8-UN | 3.5000 | 88.900 | 85.900 | 8 | 3.175 |
| 3 5/8" - 8-UN | 3.6250 | 92.075 | 89.000 | 8 | 3.175 |
| 3 3/4" - 8-UN | 3.7500 | 95.250 | 92.300 | 8 | 3.175 |
| 3 7/8" - 8-UN | 3.8750 | 98.425 | 95.400 | 8 | 3.175 |
| 4" - 8-UN | 4.0000 | 101.600 | 98.600 | 8 | 3.175 |
Reference values only. Verify against the current edition of the governing standard before use in production drawings or manufacturing. Provided by Micro Components as a free engineering resource.