- This page provided the thread dimensions of 1/8 - 27 NPTF
- NPTF stands for National Pipe Thread Fuel, based on ASTM B1.20.3.
- It is also called Dryseal Pipe Thread.
- It is a variation of the more popular NPT thread standard based on ASTM B1.20.1.
- Learn more about NPTF and the difference between NPTF and NPT
1/8 - 27 NPTF - External Basic Thread Dimensions
For interpertations of the terms scroll down to the drawings below the table
| Property | Inch | mm |
|---|---|---|
| Nominal Pipe Size(∅) | 1/8 | |
| Pipe Outside Diameter (D) | 0.405 | 10.29 |
| Fitting Outside Diameter (D2) | 0.407 | 10.34 |
| Pitch - TPI (P) | 27 | ... |
| Pitch - Distance (P) | 0.037037 | 0.9407 |
| Thread Tapper Angle (β) | 1.7893 ° | |
| Thread V half Angle (α) | 30 ° | |
| Height of sharp V (H) | 0.032080 | 0.815 |
| Thread Height (h) | 0.02513 | 0.638 |
| Root Truncation (fr) | 0.00435 | 0.11 |
| Crest Truncation (fc) | 0.0026 | 0.066 |
| End of Thread Pitch Diameter (E0) | 0.36351 | 9.233 |
| Hand-Tight Engagement Length (L1) | 0.16150 | 4.102 |
| Pitch Diameter at L1 plane (E1) | 0.37360 | 9.489 |
| Length of Last usefull Thread (L2) | 0.26390 | 6.703 |
| Pitch Diameter at L2 plane (E2) | 0.38000 | 9.652 |
| Overall Thread Length (L2 + 3P) | 0.37500 | 9.525 |
| Length of Vanish threads (V) | 0.11120 | 2.824 |
1/8 - 27 NPTF - External Thread Drawing
Overview Drawing
Profile Drawing
1/8 - 27 NPTF - Internal Basic Thread Dimensions
For interpertations of the terms scroll down to the drawings below the table
| Property | Inch | mm |
|---|---|---|
| Nominal Pipe Size(∅) | 1/8 | |
| Pitch - TPI (P) | 27 | ... |
| Pitch - Distance (P) | 0.037037 | 0.9407 |
| Thread Tapper Angle (β) | 1.7893 ° | |
| Thread V half Angle (α) | 30 ° | |
| Height of sharp V (H) | 0.4070 | 0.941 |
| Thread Height (h) | 0.02513 | 0.638 |
| Root Truncation (fr) | 0.00435 | 0.11 |
| Crest Truncation (fc) | 0.0026 | 0.066 |
| Pitch Diameter at the end of the thread (E1) | 0.37360 | 9.489 |
| Hand-Tight Engagement Length (L1) | 0.16150 | 4.102 |
| Length of Wrenching Allowance (L3) | 0.11110 | 2.822 |
| Pitch Diameter at L3 plane (E3) | 0.35660 | 9.058 |
| Ideal Tap Drill Size | 0.33230 | 8.44 |
| Nearest standard Inch drill | Q (0.332) |
1/8 - 27 NPTF - Internal Thread Drawing
Overview Drawing
Profile Drawing
1/8 - 27 NPTF - Tolerances
| Property | Minimum | Maximum |
|---|---|---|
| Thread Height (h) | 0.023380" (0.594 mm) | 0.026880" (0.683 mm) |
| Root Truncation (fr) | 0.00350" (0.089 mm) | 0.00520" (0.132 mm) |
| Crest Truncation (fc) | 0.00170" (0.043 mm) | 0.00350" (0.089 mm) |
| Tapper Angle (β) | 1.643° | 1.934° |
| Thread Head half Angle (α) | 27.5° | 32.5° |
* All other dimensions can be controlled only with gauges.
