Thread data
NPT thread chart and dimensions
American tapered pipe thread. The taper wedges tight and seals on the thread flanks with sealant or PTFE tape. Found on pumps, compressors, gauges, valves and general plumbing across North America.
- Standard
- ASME B1.20.1
- Seals by
- Taper, sealant or PTFE tape
- Used for
- Pipe, air, general plumbing
- Sizes
- 1/16 to 3
NPT dimensions
The dimensions we machine to. Pressure values are nominal working ratings for steel at room temperature.
| Size | Male | Female | Threads per inch | Pipe OD | Pitch dia E0 | Pitch dia E1 | Hand tight L1 | Effective L2 | Taper | Tap drill | Rated to |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 1/16 | 1/16-27 NPT | 1/16-27 NPT | 27 | 7.94 mm | 6.89 mm | 7.14 mm | 4.06 mm | 6.63 mm | 1:16 on diameter | C (6.15 mm) | 10,000 psi |
| 1/8 | 1/8-27 NPT | 1/8-27 NPT | 27 | 10.29 mm | 9.23 mm | 9.52 mm | 4.57 mm | 6.70 mm | 1:16 on diameter | R (8.61 mm) | 10,000 psi |
| 1/4 | 1/4-18 NPT | 1/4-18 NPT | 18 | 13.72 mm | 12.13 mm | 12.44 mm | 5.08 mm | 10.21 mm | 1:16 on diameter | 7/16 (11.11 mm) | 8,000 psi |
| 3/8 | 3/8-18 NPT | 3/8-18 NPT | 18 | 17.14 mm | 15.55 mm | 15.93 mm | 6.10 mm | 10.36 mm | 1:16 on diameter | 37/64 (14.68 mm) | 6,000 psi |
| 1/2 | 1/2-14 NPT | 1/2-14 NPT | 14 | 21.34 mm | 19.26 mm | 19.77 mm | 8.13 mm | 13.56 mm | 1:16 on diameter | 23/32 (18.26 mm) | 6,000 psi |
| 3/4 | 3/4-14 NPT | 3/4-14 NPT | 14 | 26.67 mm | 24.58 mm | 25.12 mm | 8.61 mm | 13.86 mm | 1:16 on diameter | 59/64 (23.42 mm) | 5,000 psi |
| 1 | 1-11.5 NPT | 1-11.5 NPT | 11.5 | 33.40 mm | 30.83 mm | 31.46 mm | 10.16 mm | 17.34 mm | 1:16 on diameter | 1 5/32 (29.36 mm) | 5,000 psi |
| 1 1/4 | 1 1/4-11.5 NPT | 1 1/4-11.5 NPT | 11.5 | 42.16 mm | 39.55 mm | 40.22 mm | 10.67 mm | 17.95 mm | 1:16 on diameter | 1 1/2 (38.10 mm) | 3,000 psi |
| 1 1/2 | 1 1/2-11.5 NPT | 1 1/2-11.5 NPT | 11.5 | 48.26 mm | 45.62 mm | 46.29 mm | 10.67 mm | 18.38 mm | 1:16 on diameter | 1 47/64 (44.04 mm) | 3,000 psi |
| 2 | 2-11.5 NPT | 2-11.5 NPT | 11.5 | 60.32 mm | 57.63 mm | 58.33 mm | 11.07 mm | 19.22 mm | 1:16 on diameter | 2 7/32 (56.36 mm) | 2,500 psi |
| 2 1/2 | 2 1/2-8 NPT | 2 1/2-8 NPT | 8 | 73.02 mm | 69.08 mm | 70.54 mm | 23.50 mm | 28.89 mm | 1:16 on diameter | 2 5/8 (66.67 mm) | 2,000 psi |
| 3 | 3-8 NPT | 3-8 NPT | 8 | 88.90 mm | 84.85 mm | 86.36 mm | 24.13 mm | 30.48 mm | 1:16 on diameter | 3 1/4 (82.55 mm) | 1,500 psi |
Adapters with NPT
NPT to JIC adaptersNPT to ORB adaptersNPT to BSPP adaptersNPT to BSPT adaptersNPT to Metric adaptersNPT to ORFS adaptersNPT to Push to connect adaptersNPT to Tri-clamp adaptersNPT to Micro thread adaptersNPT to Luer adaptersNPT to Hose barb adaptersGarden hose (GHT) to NPT adaptersSAE 45° flare to NPT adaptersNPSM to NPT adaptersNPT to Compression adaptersNPT to Slip adapters
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