NPT Thread Dimensions [PDF]

Citation preview

Basic Dimensions, American National Standard Taper Pipe Threads, NPT. ANSI/ASME B1.20.1-1983 (R1992)



For all dimensions, see corresponding reference letter in table Angle between sides of thread is 60 degrees. Taper of thread, on diameter, is 3 ⁄4 inch per foot. Angle of taper with center line is 1°47′. The basic maximum thread height, h, of the truncated thread is 0.8 × pitch of thread. The crest and root are truncated a minimum of 0.033 × pitch for all pitches. For maximum depth of truncation, see ASME B1-20-1. Nominal Pipe Size In.



Outside Threads Pitch Pitch Handtight Dia. of per of Diameter at Engagement Pipe, Inch, Thread, Beginning Length, b D n p of External L1, mm. Thread, E0



1/16 1/8 1/4 3/8 1/2 3/4 1 1 1/4 1 1/2 2 2 1/2 3 3 1/2 4 5 6 8 10 12 14 OD 16 OD 18 OD 20 OD 24 OD



7.94 10.29 13.72 17.15 21.34 26.67 33.40 42.16 48.26 60.33 73.03 88.90 101.60 114.30 141.30 168.28 219.08 273.05 323.85 355.60 406.40 457.20 508.00 609.60



27 27 18 18 14 14 11 1/2 11 1/2 11 1/2 11 1/2 8 8 8 8 8 8 8 8 8 8 8 8 8 8



0.94 0.94 1.41 1.41 1.81 1.81 2.21 2.21 2.21 2.21 3.18 3.18 3.18 3.18 3.18 3.18 3.18 3.18 3.18 3.18 3.18 3.18 3.18 3.18



6.89 9.23 12.13 15.55 19.26 24.58 30.83 39.55 45.62 57.63 69.08 84.85 97.47 110.09 136.92 163.73 214.21 267.85 318.33 349.89 400.37 450.85 501.33 602.30



a



4.06 4.10 5.79 6.10 8.13 8.61 10.16 10.67 10.67 11.07 17.32 19.46 20.85 21.44 23.80 24.33 27.00 30.73 34.54 39.67 46.02 50.80 53.98 60.33



Dia.,a E1



Effective Thread, Length, c L2, mm.



Dia., E2



7.14 9.49 12.49 15.93 19.77 25.12 31.46 40.22 46.29 58.33 70.16 86.07 98.78 111.43 138.41 165.25 215.90 269.77 320.49 352.36 403.24 454.03 504.71 606.07



6.63 6.70 10.21 10.36 13.56 13.86 17.34 17.95 18.38 19.22 28.89 30.48 31.75 33.02 35.72 38.42 43.50 48.90 53.98 57.15 62.23 67.31 72.39 82.55



7.30 9.65 12.76 16.19 20.11 25.45 31.91 40.67 46.77 58.83 70.88 86.76 99.46 112.16 139.16 166.13 216.93 270.91 321.71 353.46 404.26 455.06 505.86 607.46



Wrench Makeup Vanish Overall Length for Internal Thread Thread, Length (3.47 External Dia., Length, f thds.), Thread, E3 L3 V L4



2.82 2.82 4.23 4.23 5.44 5.44 6.63 6.63 6.63 6.63 6.35 6.35 6.35 6.35 6.35 6.35 6.35 6.35 6.35 6.35 6.35 6.35 6.35 6.35



g g



6.71 9.06 11.86 15.28 18.92 24.24 30.41 39.14 45.21 57.22 68.68 84.46 97.08 109.70 136.53 163.33 213.82 267.45 317.94 349.49 399.97 450.45 500.94 601.90



3.26 3.26 4.90 4.90 6.29 6.29 7.66 7.66 7.66 7.66 11.02 11.02 11.02 11.02 11.02 11.02 11.02 11.02 11.02 11.02 11.02 11.02 11.02 11.02



9.90 9.97 15.10 15.26 19.85 20.15 25.01 25.62 26.04 26.88 39.91 41.50 42.77 44.04 46.74 49.43 54.51 59.91 64.99 68.17 73.25 78.33 83.41 93.57



Nominal Perfect External Threads d Length, Dia., L5 E5



4.75 4.82 7.38 7.54 9.93 10.23 12.93 13.54 13.96 14.80 22.54 24.13 25.40 26.67 29.37 32.07 37.15 42.55 47.63 50.80 55.88 60.96 66.04 76.20



7.18 9.53 12.59 16.02 19.88 25.22 31.63 40.40 46.49 58.56 70.49 86.36 99.06 111.76 138.76 165.74 216.54 270.51 321.31 353.06 403.86 454.66 505.46 607.06



Height Basic Minor of Dia. at Small Thread, End of Pipe, e h K0



0.75 0.75 1.13 1.13 1.45 1.45 1.77 1.77 1.77 1.77 2.54 2.54 2.54 2.54 2.54 2.54 2.54 2.54 2.54 2.54 2.54 2.54 2.54 2.54



6.14 8.48 11.00 14.42 17.81 23.13 29.06 37.79 43.85 55.87 66.54 82.31 94.93 107.55 134.38 161.19 211.67 265.31 315.79 347.35 397.83 448.31 498.79 599.76



Also pitch diameter at gaging notch (handtight plane). Also length of thin ring gage and length from gaging notch to small end of plug gage. c Also length of plug gage. d The length L5 from the end of the pipe determines the plane beyond which the thread form is imperfect at the crest. The next two threads are perfect at the root. At this plane the cone formed by the crests of the thread intersects the cylinder forming the external surface of the pipe. L5 = L2 - 2p. e Given as information for use in selecting tap drills. f Three threads for 2-inch size and smaller; two threads for larger sizes. g Military Specification MIL—P—7105 gives the wrench makeup as three threads for 3 in. and smaller. The E 3 dimensions are then as follows: Size 2½ in., 68.48 mm and size 3 in., 84.26 mm.



b



All dimensions are in mm



by Neil Louis. Taken from ASME B1-20-1 and Machineries Handbook.