
unit: mm Bored Hole reference Minor Diameter Size (reference) Tap
Size L1 L3 L1+L3 Position away from Pipe End by
| Pipe End (Basic Diameter Position) | Maximum | Basic | ||||||
| (L1+L3) | Size of | Diameter | ||||||
| Maximum | Minimum | Maximum | Minimum | Straight | Position | |||
| Tolerance | Tolerance | Bored Hole | ℓg | |||||
| Value | Value | Value | Value |
| ① | ② | ③ | ④ | ⑤ | ⑥ | ⑦ | ⑧ | ⑨ | ⑩ | ⑪ | ⑫ | |
| NPT | 1/16 - 27 | 4.064 | 2.822 | 6.886 | 6.510 | 6.388 | 0.122 | 6.080 | 5.958 | 0.122 | 6.05 | 12.00 |
| NPT | 1/8 - 27 | 4.102 | 2.822 | 6.924 | 8.857 | 8.736 | 0.122 | 8.425 | 8.303 | 0.122 | 8.39 | 12.05 |
| NPT | 1/4 - 18 | 5.786 | 4.234 | 10.020 | 11.514 | 11.357 | 0.157 | 10.888 | 10.730 | 0.157 | 10.85 | 17.45 |
| NPT | 3/8 - 18 | 6.096 | 4.234 | 10.330 | 14.953 | 14.796 | 0.157 | 14.308 | 14.150 | 0.157 | 14.27 | 17.65 |
| NPT | 1/2 - 14 | 8.128 | 5.443 | 13.571 | 18.485 | 18.323 | 0.163 | 17.637 | 17.475 | 0.163 | 17.60 | 22.85 |
| NPT | 3/4 - 14 | 8.611 | 5.443 | 14.054 | 23.831 | 23.668 | 0.163 | 22.952 | 22.790 | 0.163 | 22.91 | 22.95 |
| NPT | 1 - 11.5 | 10.160 | 6.627 | 16.787 | 29.868 | 29.696 | 0.173 | 28.819 | 28.647 | 0.173 | 28.78 | 27.40 |
| NPT | 1 1/4 - 11.5 | 10.668 | 6.627 | 17.295 | 38.625 | 38.452 | 0.173 | 37.544 | 37.372 | 0.173 | 37.50 | 28.10 |
| NPT | 1 1/2 - 11.5 | 10.668 | 6.627 | 17.295 | 44.695 | 44.522 | 0.173 | 43.614 | 43.441 | 0.173 | 43.57 | 28.40 |
| NPT | 2 - 11.5 | 11.074 | 6.627 | 17.701 | 56.732 | 56.560 | 0.173 | 55.626 | 55.454 | 0.173 | 55.58 | 28.00 |
Remarks 1. Pipe End is Basic Diameter Position (E1). NPT INTERNAL THREAD Remarks 2. Effective Thread Length is the length away from Pipe End by (L1+L3). L3 L1
on taps, taper bored hole is recommended.
NPT EXTERNAL THREAD values in shown columns ⑤, ⑥ ⑧, ⑨,
reaming by taking reamer's margin into account.
diameter.