External (pipe) Basic Thread Dimensions
For interpertations of the terms scroll down to the drawings below the table
| Property | Inch | mm |
|---|---|---|
| Nominal Pipe Size (Ø) | 3/8" | ... |
| Pipe Outside Diameter (D) | 0.675 | 17.145 |
| Pitch (TPI) (P) | 18.000 | 457.2 |
| Pitch (Distance) (P) | 0.05555556 | 1.411 |
| Thread Tapper Angle (ß) | 1.7893° | 1.7893° |
| Thread V half Angle (α) | 30° | 30° |
| Height of sharp V (H) | 0.048113 | 1.222 |
| Thread height (h) | 0.04444 | 1.129 |
| Pitch Diameter at the Pipe's end (E0) | 0.61201 | 15.545 |
| Minor Diameter at the Pipe's end (K0) | 0.5676 | 14.417 |
| Hand-Tight Engagement Length (L1) | 0.24 | 6.096 |
| Pitch Diameter at L1 plane (E1) | 0.62701 | 15.926 |
| Length of Last Complete Thread (L5) | 0.2967 | 7.536 |
| Pitch Diameter at L5 plane (E5) | 0.63056 | 16.016 |
| Length of Last usefull Thread (L2) | 0.4078 | 10.358 |
| Pitch Diameter at L2 plane (E2) | 0.6375 | 16.193 |
| Overall Thread Length (L4) | 0.6006 | 15.255 |
| Length of Vanish threads (V) | 0.1928 | 4.897 |
3/8-18 NPT - External (pipe) Drawing
Overview Drawing
Profile Drawing
3/8-18 NPT - Internal (Fitting) Basic Thread Dimensions
For interpertations of the terms scroll down to the drawings below the table
| Property | Inch | mm |
|---|---|---|
| Nominal Pipe Size (Ø) | 3/8" | ... |
| Pipe Outside Diameter (D) | 0.675 | 17.145 |
| Pitch (TPI) (P) | 18.000 | 457.2 |
| Pitch (Distance) (P) | 0.05555556 | 1.411 |
| Thread Tapper Angle (ß) | 1.7893° | 1.7893° |
| Thread V half Angle (α) | 30° | 30° |
| Height of sharp V (H) | 0.048113 | 1.222 |
| Thread height (h) | 0.04444 | 1.129 |
| Pitch Diameter at the fitting's end (E1) | 0.62701 | 15.926 |
| Length of Hand-Tight Engagemen (L1) | 0.24 | 6.096 |
Length of Wrenching Allowance (L3) |
0.1667 | 4.234 |
| Pitch Diameter at L3 plane (E3) | 0.6016 | 15.281 |
| Tap Drill Size (T) | 0.5625 | 14.288 |
3/8-18 NPT - Internal (Fitting) Drawing
Overview Drawing
Profile Drawing
3/8-18 NPT - Tolerances
| Property | Minimum | Maximum |
|---|---|---|
| Thread Height (h) | 0.03833" (0.974 mm) | 0.04444" (1.129 mm) |
| L1 gage Tolerance (+/- 1 Turn) (L1) | ... | 0.05556" (1.411 mm) |
| Thread Truncation (f) | 0.0018" (0.046 mm) | 0.0049" (0.124 mm) |
| Tapper angle Variation (ß) | 1.641" ( ) | 2.089" ( ) |
| Thead V Half Angle (+/-) (α) | ... | 1" ( ) |
| Thread Height (h) | " (0 mm) | " (0 mm) |
| L1 gage Tolerance (+/- 1 Turn) (L1) | " ( ) | " ( ) |
| Thread Truncation (f) | " (0 mm) | " (0 mm) |
| Tapper angle Variation (ß) | " ( ) | " ( ) |
| Thead V Half Angle (+/-) (α) | " ( ) | " ( ) |
