- This page provided the thread dimensions of 1 1/4 - 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 1/4 - 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 1/4 | |
| Pipe Outside Diameter (D) | 1.66 | 42.16 |
| Fitting Outside Diameter (D2) | 1.672 | 42.47 |
| 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) | 1.55713 | 39.551 |
| Hand-Tight Engagement Length (L1) | 0.42000 | 10.668 |
| Pitch Diameter at L1 plane (E1) | 1.58338 | 40.218 |
| Length of Last usefull Thread (L2) | 0.70680 | 17.953 |
| Pitch Diameter at L2 plane (E2) | 1.60130 | 40.673 |
| Overall Thread Length (L2 + 3P) | 0.96880 | 24.608 |
| Length of Vanish threads (V) | 0.26200 | 6.655 |
1 1/4 - 11 1/2 NPTF - External Thread Drawing
Overview Drawing
Profile Drawing
1 1/4 - 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 1/4 | |
| 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) | 1.6720 | 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) | 1.58338 | 40.218 |
| Hand-Tight Engagement Length (L1) | 0.42000 | 10.668 |
| Length of Wrenching Allowance (L3) | 0.26090 | 6.627 |
| Pitch Diameter at L3 plane (E3) | 1.54080 | 39.136 |
| Ideal Tap Drill Size | 1.48050 | 37.605 |
| Nearest standard Inch drill | 1 31/64 (1.484) |
1 1/4 - 11 1/2 NPTF - Internal Thread Drawing
Overview Drawing
Profile Drawing
1 1/4 - 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.
