Pipe Threading Standards
Petersen Does Not Sell Pipe
Pipe Threading Acronyms
NPS: Nominal Pipe Size (Not the pipe ID or OD)
NPT: National Pipe Thread (tapered) is a U.S. standard for tapered threads
FPT, or FNPT, or NPT(F): Female Pipe Thread (interchangeable with NPT)
FIP: Female Iron Pipe (interchangeable with NPT)
MPT, MNPT or NPT(M): Male Pipe Thread (interchangeable with NPT)
MIP: Male Iron Pipe (interchangeable with NPT)
NPTF: National (American Dryseal)) Pipe Thread, Fuel, for leak-free seal without thread sealant
NPS: National (American) Pipe Straight (parallel thread instead of taper) uses a gasket or O-ring to seal.
NPSF: National (American) Pipe Straight (parallel thread instead of taper) Fuel
BSPT: British Standard Pipe Thread Tapered
BSPP: British Standard Pipe Thread Parallel
IPS: Iron Pipe Straight
IPT: Iron Pipe Thread
TPI: Threads Per Inch
WOG: Water Oil Gas
SCH: Schedule
UNF: Unified Fine Thread Series
NPT: Pipe Thread Sizes
Nominal pipe size |
Thread density |
Thread pitch | Hand-tight engagement | Effective thread | Overall length |
Actual outside diameter, OD |
Tap drill | |||||||
Length | Turns | Diameter | Length | Turns | Diameter | |||||||||
inch | inch −1 | inch | mm | inch | inch | inch | inch | inch | inch | mm | inch | mm | ||
1⁄16 | 27 | 0.037 | 0.940 | 0.16 | 4.32 | 0.281 | 0.261 | 7.05 | 0.288 | 0.390 | 0.313 | 7.95 | ||
1⁄8 | 27 | 0.037 | 0.940 | 0.161 | 4.36 | 0.374 | 0.264 | 7.13 | 0.380 | 0.392 | 0.405 | 10.29 | 0.339 | 8.611 |
1⁄4 | 18 | 00.056 | 1.411 | 0.227 | 4.1 | 0.492 | 0.402 | 7.23 | 0.503 | 0.595 | 0.54 | 13.72 | 7⁄16 | 11.11 |
3⁄8 | 18 | 00.056 | 1.411 | 0.24 | 4.32 | 0.627 | 0.408 | 7.34 | 0.638 | 0.601 | 0.675 | 17.15 | 37⁄64 | 14.69 |
1⁄2 | 14 | 00.071 | 1.814 | 0.32 | 4.48 | 0.778 | 0.534 | 7.47 | 0.792 | 0.782 | 0.84 | 21.34 | 23⁄32 | 18.257 |
3⁄4 | 14 | 00.071 | 1.814 | 0.339 | 4.75 | 0.989 | 0.546 | 7.64 | 1.002 | 0.794 | 1.05 | 26.67 | 59⁄64 | 23.416 |
1 | 11 1⁄2 | 0.087 | 2.208 | 0.4 | 4.6 | 1.24 | 0.683 | 7.85 | 1.256 | 0.985 | 1.315 | 33.40 | 1 5⁄32 | 29.37 |
1 1⁄4 | 11 1⁄2 | 0.087 | 2.208 | 0.42 | 4.83 | 1.58 | 0.707 | 8.13 | 1.601 | 1.009 | 1.66 | 42.16 | 1 1⁄2 | 38.1 |
1 1⁄2 | 11 1⁄2 | 00.087 | 2.208 | 0.42 | 4.83 | 1.822 | 0.724 | 8.32 | 1.841 | 1.025 | 1.9 | 48.26 | 1 47⁄64 | 44.05 |
2 | 11 1⁄2 | 0.087 | 2.208 | 0.436 | 5.01 | 2.300 | 0.757 | 8.7 | 2.316 | 1.058 | 2.375 | 60.33 | 2 7⁄32 | 56.36 |
2 1⁄2 | 8 | 0.125 | 3.175 | 0.682 | 5.46 | 2.762 | 1.138 | 9.1 | 2.791 | 1.571 | 2.875 | 73.03 | 2 5⁄8 | 66.68 |
3 | 8 | 0.125 | 3.175 | 0.766 | 6.13 | 3.39 | 1.20 | 9.6 | 3.416 | 1.634 | 3.5 | 88.9 | 3 1⁄4 | 82.55 |
3 1⁄2 | 8 | 0.125 | 3.175 | 0.821 | 6.57 | 3.89 | 1.25 | 10 | 3.916 | 1.684 | 4 | 101.6 | 3 3⁄4 | 95.25 |
4 | 8 | 0.125 | 3.175 | 0.844 | 6.75 | 4.39 | 1.3 | 10.4 | 4.416 | 1.734 | 4.5 | 114.3 | 4 1⁄4 | 107.95 |
4 1⁄2 | 8 | 0.125 | 3.175 | 5 | 127 | 4 3⁄4 | 120.65 | |||||||
5 | 8 | 0.125 | 3.175 | 0.937 | 7.5 | 5.449 | 1.406 | 11.25 | 5.479 | 1.84 | 5.563 | 141.30 | 5 9⁄32 | 134.14 |
6 | 8 | 0.125 | 3.175 | 0.958 | 7.66 | 6.506 | 1.513 | 12.1 | 6.541 | 1.946 | 6.625 | 168.28 | 6 11⁄32 | 161.13 |
8 | 8 | 0.125 | 3.175 | 1.063 | 8.5 | 8.500 | 1.713 | 13.7 | 8.541 | 2.146 | 8.625 | 219.06 | ||
10 | 8 | 0.125 | 3.175 | 1.21 | 9.68 | 10.62 | 1.93 | 15.4 | 10.666 | 2.359 | 10.75 | 273.05 | ||
12 | 8 | 0.125 | 3.175 | 1.36 | 10.88 | 12.62 | 2.13 | 17 | 12.666 | 2.559 | 12.75 | 323.85 | ||
14 | 8 | 0.125 | 3.175 | 1.562 | 12.5 | 13.87 | 2.25 | 18 | 13.916 | 2.684 | 14 | 355.6 | ||
16 | 8 | 0.125 | 3.175 | 1.812 | 14.5 | 15.88 | 2.45 | 19.6 | 15.916 | 2.884 | 16 | 406.4 | ||
18 | 8 | 0.125 | 3.175 | 2 | 16 | 17.88 | 2.65 | 21.2 | 17.916 | 3.084 | 18 | 457.2 | ||
20 | 8 | 0.125 | 3.175 | 2.125 | 17 | 19.87 | 2.85 | 22.8 | 19.916 | 3.284 | 20 | 508 | ||
24 | 8 | 0.125 | 3.175 | 2.375 | 19 | 23.86 | 3.25 | 26 | 23.916 | 3.684 | 24 | 609.6 |
Information is based on Wikipedia article, National pipe thread and is for reference only and should be verified by related pipe thread standards. Number of decimals expressed not necessarily indicative of manufacturing tolerances.
The information may be used but with no warranty or liability. These pipe thread standard definitions are believed to be correct but should always be double-checked with alternative sources. Strictly adhere to and follow all applicable national and local regulations and practices.
Pipe Plugs for Testing, Blocking, Bypassing, Line Stopping, and More
- Pipe Plug, High Pressure Block & Bleed, 127BB Series
- Pipe Plug, Low Pressure Gas, 154 Series
- Pipe Plug, MF High Expansion, 113 Series
- Pipe Plug, MF, High Pressure, 127 Series
- Pipe Plug, MF, Oil Res. w or wo bypass, Heavy Duty, 124-125 Series
- Pipe Plug, MF, Oil Resist. with or without bypass 114-115 Series
- Pipe Plug, Rigid Core, Bore Hole Plugs with Bypass 126 Series
- Pipe Plug, Aramid Reinforced 136 Series Bypass
- Pipe Plug, Bypass 130-2 Series
- Pipe Plug, Large Bypass, 130-6 Series, Multi Size
- Pipe Plug, Leak Detector, 130-4 Series
- Pipe Plug, Pillow, Heavy Duty, 130-9 Series
- Pipe Plug, Plumber Test Style Rubber Plugs 137 Series
- Pipe Plug, Remote Placement, 130-7 Series
- Pipe Plug, Rubber Plumber, 130-0 Series
- Pipe Plug, Rubber Stack Test, 130-1 Series
- Pipe Plug, Rubber, Long Test 130-3 Series
- Custom Mechanical Plugs, 145-2
- Pipe Plug Flange Weld Test, 151 Series
- Pipe Plug, EZ-Swet, Stopper, 148-0 Series
- Pipe Plug, Hand Tight 2 Seals, 149-2 Series
- Pipe Plug, Hand Tight, Bypass 149-1 Series
- Pipe Plug, High PSI, Block & Bleed 145-1 Series
- Pipe Plug, Mech High Pressure Test 145-9 Series
- Pipe Plug, Med PSI Test, Bypass 146-9 Series
- Pipe Plug, Remote Placement, 148-3 Series
- Pipe Plug, Very High PSI, Bypass, 147-1 Series
- Pipeline Joint Testers, Sizes 24 to 120in, 145-8 Series
- Safety Gags for Mechanical Pipe Plug
- Through the Valve Line Stop
- Hand Tightening Nylon Test & Cleanout Plugs, Sizes 1.5" to 4", 143-0 Series
- Lever Type Expandable Rubber Plugs, Sizes 0.375" to 4", 143-1 Series
- Pipe Plug, ABS & SS Threaded 143-8 Series
- Pipe Plug, ABS Low Psi, Pipe End, 144-1 Series
- Pipe Plug, ABS Pipe End, 143-9 Series
- Pipe Plug, Flush Mounted, 140-4, 5 Series
- Pipe Plug, Low Pressure Bypass, 141-0 Series
- Pipe Plug, Mechanical Hand Tightening, 144-0 Series
- Pipe Plug, Nylon, Hand Tite, 142-0 Series
- Pipe Plug, Pipe Protector, Bell or Spigot, 140-0 Series
- Pipe Plug, Polypropylene End Of Pipe, 143-4
- Pipe Plug, Steel Wing Nut, 143-3 Series
- Pipe Plug, T-Handle Aluminum, 143-7 Series
- Pipe Plug, Tapered Redwood, 140-1 Series
- Pipe Plug, Water Line Stub, 143-5
- Pipe Plug, Well Monitoring, 142-8 Series
- Pipe Plug, Wing Nut 2 Seals, 141-2 Series
- Pipe Plug, Wing Nut Hand Tight, 141-1 Series
- Rubber Seal Pipe Plug, 143-2 Series
- Test Caps, Sizes 1.5" to 6", 142-9 Series
- Deflection Gauges For Pipeline Diameter Integrity
- Leak Detector Pressure Testing, 924-1304 Series
- Manhole Vacuum Test Equipment
- Parachutes, Stringers, Ventilators
- Pipeline Joint Testers, 24in to 120in
- Pump, Hydrostatic Test, Diaphragm & Gas Engine
- Pump, Hydrostatic Test, High Pressure, 938-9 Series
- Smoke Testers, 938-95 Series