- This page provided the thread dimensions of 1 - 11 1/2 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 - 11 1/2 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 | |
| Pipe Outside Diameter (D) | 1.315 | 33.4 |
| Fitting Outside Diameter (D2) | 1.327 | 33.71 |
| Pitch - TPI (P) | 12 | ... |
| Pitch - Distance (P) | 0.086957 | 2.2087 |
| Thread Tapper Angle (β) | 1.7893 ° | |
| Thread V half Angle (α) | 30 ° | |
| Height of sharp V (H) | 0.075310 | 1.913 |
| Thread Height (h) | 0.06446 | 1.637 |
| Root Truncation (fr) | 0.0065 | 0.165 |
| Crest Truncation (fc) | 0.00435 | 0.11 |
| End of Thread Pitch Diameter (E0) | 1.21363 | 30.826 |
| Hand-Tight Engagement Length (L1) | 0.40000 | 10.16 |
| Pitch Diameter at L1 plane (E1) | 1.23863 | 31.461 |
| Length of Last usefull Thread (L2) | 0.68280 | 17.343 |
| Pitch Diameter at L2 plane (E2) | 1.25630 | 31.91 |
| Overall Thread Length (L2 + 3P) | 0.93750 | 23.813 |
| Length of Vanish threads (V) | 0.25470 | 6.469 |
1 - 11 1/2 NPTF - External Thread Drawing
Overview Drawing
Profile Drawing
1 - 11 1/2 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 | |
| Pitch - TPI (P) | 12 | ... |
| Pitch - Distance (P) | 0.086957 | 2.2087 |
| Thread Tapper Angle (β) | 1.7893 ° | |
| Thread V half Angle (α) | 30 ° | |
| Height of sharp V (H) | 1.3270 | 2.209 |
| Thread Height (h) | 0.06446 | 1.637 |
| Root Truncation (fr) | 0.0065 | 0.165 |
| Crest Truncation (fc) | 0.00435 | 0.11 |
| Pitch Diameter at the end of the thread (E1) | 1.23863 | 31.461 |
| Hand-Tight Engagement Length (L1) | 0.40000 | 10.16 |
| Length of Wrenching Allowance (L3) | 0.26090 | 6.627 |
| Pitch Diameter at L3 plane (E3) | 1.19730 | 30.411 |
| Ideal Tap Drill Size | 1.13900 | 28.931 |
| Nearest standard Inch drill | 1 9/64 (1.141) |
1 - 11 1/2 NPTF - Internal Thread Drawing
Overview Drawing
Profile Drawing
1 - 11 1/2 NPTF - Tolerances
| Property | Minimum | Maximum |
|---|---|---|
| Thread Height (h) | 0.062310" (1.583 mm) | 0.066610" (1.692 mm) |
| Root Truncation (fr) | 0.00520" (0.132 mm) | 0.00780" (0.198 mm) |
| Crest Truncation (fc) | 0.00350" (0.089 mm) | 0.00520" (0.132 mm) |
| Tapper Angle (β) | 1.643° | 1.934° |
| Thread Head half Angle (α) | 28.5° | 31.5° |
* All other dimensions can be controlled only with gauges.
