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Pipe Thread Acronym Definitions

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
116 27 0.037 0.940 0.16 4.32 0.281 0.261 7.05 0.288 0.390 0.313 7.95
18 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
14 18 00.056 1.411 0.227 4.1 0.492 0.402 7.23 0.503 0.595 0.54 13.72 716 11.11
38 18 00.056 1.411 0.24 4.32 0.627 0.408 7.34 0.638 0.601 0.675 17.15 3764 14.69
12 14 00.071 1.814 0.32 4.48 0.778 0.534 7.47 0.792 0.782 0.84 21.34 2332 18.257
34 14 00.071 1.814 0.339 4.75 0.989 0.546 7.64 1.002 0.794 1.05 26.67 5964 23.416
1 11 12 0.087 2.208 0.4 4.6 1.24 0.683 7.85 1.256 0.985 1.315 33.40 1 532 29.37
1 14 11 12 0.087 2.208 0.42 4.83 1.58 0.707 8.13 1.601 1.009 1.66 42.16 1 12 38.1
1 12 11 12 00.087 2.208 0.42 4.83 1.822 0.724 8.32 1.841 1.025 1.9 48.26 1 4764 44.05
2 11 12 0.087 2.208 0.436 5.01 2.300 0.757 8.7 2.316 1.058 2.375 60.33 2 732 56.36
2 12 8 0.125 3.175 0.682 5.46 2.762 1.138 9.1 2.791 1.571 2.875 73.03 2 58 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 14 82.55
3 12 8 0.125 3.175 0.821 6.57 3.89 1.25 10 3.916 1.684 4 101.6 3 34 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 14 107.95
4 12 8 0.125 3.175 5 127 4 34 120.65
5 8 0.125 3.175 0.937 7.5 5.449 1.406 11.25 5.479 1.84 5.563 141.30 5 932 134.14
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 1132 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.