ansi asme b1.20.1-1983
DESCRIPTION
ASMETRANSCRIPT
)AN AMERICAN NATIONAL STANDARD
PIPE THREADS, GENERAL PURPOSE (INCH)
ANS|/ASME 81.20.1-1g€Xl
12.3 Coated or Plated Threads. The threadedproduct specifications covered in this Standard donot include an allowance for coatings or plating.
1.3 Sealing
1.3.1 Where pressure-tight joints are required, it isintended that taper pipe threads conforming to thisStandard be made up wrench-tight with a sealant"
To prevent galling on certain piping materials such as
stainless steels, the sealant usually contains a lubricant"
1.3.2 Pipe threads designed for pressure-tightjoints that may be used without sealing compounds(Dryseal Threads) are covered in ANSI B1.20.3 (Inch)and ANSI Bl.2O.4 (Metric Transtation)"
1.4 lnspection
A gaging method and tolerances are prescribed inthis Standard to effect a functional inqpection ofthehandtight .L1 engagement threads. However, con-formance to this Standard requires that all basic
design dimensions be met (within applicable toler-ances) including extension of the thread elements toprovide for wrench-tight makeup. Therefore, addi-tional methods of gaglng may be employed toevaluate conformance to the basic design dimensions.When additional melhods of gaging are employed,they shall be agreed upon by the supplier and thepurchaser.
1.5 Appendix
Useful and supplementary information which isnot a part of this Standard is presented in the Appen-dix. Specifically, the Appendix gives Suggested TwistDrill Dameters for Drilled Hole Sizes for PipeThreads"
1.6 Related Standard
Definitions of terms and symbols for thread dimensions are given in ANSI 81.7, Nomenclature,Definitions and Letter Symbols for Screw Threads"
1 INTRODUCTION
1"1 Scope
This American National Standard covers dimen-sions and gaging of pipe threads for general purposeapplications.
'1.2 Thread Designations
1.2.1 The types of pipe threads included in thisStandard are designhtetl by specifying frt sequence
the nominal pipe size,l number of threads per inchand the tluead series symbol as follows:
3/8 - 18 NPTl/8 - 27 NPSC
tl2 -t4 NPTR" rl8 - 27 NPSM
l/8 - 27 NPSL1 - 1I.5 NPSH
For left hand threads add LH to the designation,otherwise right hand threads will be understood" Forexample:
3/8 - 18 NPT - LH
1.2.2 Each of these letters in the rymbols has adefinite significance as follows:
N = National (American) StandardP = PipeT = TaperC = CouplingS = StraightM = Mechanical
L = LocknutH = Hose CouplingR = Railing Fittings
rWhere it is necessary to use decimal notation for the sizedesignation (as when inserting such in a @mputer or elec-
tronic accounting machine) the decimal equivalent of nom-inal pipe size may be substituted for fractional pipe sizer
AN AMERICAN NATIONALPIPE THREADS, GENERAL
STANDARDPURPOSE IINCHI ANSUASME 81.20.'[-19&t
External Thread lnternal Thread
NOTATIONH= o-866025p=heishtof60deg.sharpvthread F = tdeg.47min.=threadtaperangreforr/16taper
q
n-\^/l c
'.( L
t - O.8OOOOQ = heightof threadonproductp G 17, = pitch {measured parallel to axis}n = number of threads per inchC"= 3Odeg. = threadflankangle
f" = depth of truncation at crestf. = depth of truncation at rootF" = width of flat at crestFr = width of flat at root
GENERAL NorE: For a symmetrical straight screw thread, H=cotgJ2n.Forarymmetrical tape-rscrewthread,H= {cotc-tan2 ptanall2n,sothattheexactvalueforanAmericanNationat s."no"rj'r"p"r;;;;;;;"=o.ruuroro".against ll = 0'86602$p, the value given above. For an Spitch thread, which is the coarsest standard taper pipe thread pitch,the corresponding values of H are o-1 o82l 8 and 0.1 08253 respectively, the difference being 0.00oo35 inch. Th is d ifferencebeing too small to be significant. the value of H = 0.866025p conrinues in use for threads of 0.750 in., or less. taper/ft onthe diameter.
FIG" 1 BASIC FORM OF AMERTCAN NATIONAL STANDARD TAPER PIPE THREB.[]
2 e
Tl,-i
9O des.
ttt
AN AMERICAN NATIONAL STANDARDPIPE THREADS, GENERAL PURPOSE (INCHI
Pitch line
ANSUASME 81.20.1-1983
{
E3
I
Taper of thread1 in 16 measuredon diameter
', I
Fo
I
TABLE 2 BASIC DIMENSIONS OF AMERICAN NATIONAL STANDARD TAPER PIPE THREAD, NPTT
NominalPipeSize
1
O.D. ofPipe(Dl
Threads/in.lnl
Pitch ofThrsad
lPl
Pitch Diam.at Beginningof ExternalThread (Fol
Handtight Engagement Effective Thr€ad, ExternalLength2 (Lr I
Diam.3(Erl
Lengrttra (tzlDiam"lEzlinch Threads inch Threads
2 3 4 5 6 7 8 9 10 11th,
kv,7"
v,- ,/o
1
1Y41Y22
14 0.D.l6 0.D"'I 8 0.D.20 0.D"24 0.D.
2th3
,tZ
5
68
10
l2
0.31 250"405
0.s400.67 5
, o.8401.050
1.3151.6601.9002.37s
2.87 S3.5004.0004.500
5.5 636-6258.625
10.750't2.7 50
14.00016.000'18.000
20.00024.000
11.5r 1.51 1.5I t-5
2727
18
l81414
8888
888
88
888
8
8
0.o37040.03704
0.055560.05556; l,'fJ .
o.071430.o7143
0.086960.086860.086960.08696
0. I 25000.1 25000.1 25000. t 2500
0.1 25000. I 25000. I 25000.1 25000.i 2500
0.1 25000.1 25000.'r 25000. I 25000.1 2500
o.27"t180.36351
0.477390.61201
0.758430.96768
1.213631.5571 3
1.796092.26902
2.719533.340623.837s04.33438
5.390736.446098.43359
10.5453112.s3281
1 3.7750015.7 62501 7.750001 9.7375023.712sO
0.1600.1 61 5
o.22780.240'o.320
0.339
0.400o.420o.4200.436
0.6820.7 660.821o.844
0.9370.9581.0631.2101.360
1.s621.8122.0002.1252.37 5
4.484.75
4.604.834.835.01
5.466.136.s76.7 5
7.507.668.509.68
10.88
12.5014.5016.0017.0019.00
4.324.36
4.104.32
0.281180.37360
o-491630.62701r r YY' -|. +. s' \0.77843 '
0.98887
1.238631.s83381.822342,29627
2.762163.388503.888814.38712 l
I
s.44s2s I
6.sose7 I
8.s0003 I
10.620s4 I
12.61781 I
13.87262 I
rs.8757s I
17.87s00 I
t e.87031 I
23.860e4 I
0.2611o.2639
0.40180.4078
0.53370.5457
0.68280.70680.72350.7 565
1.137 5
1.20001.2500,1.3000
1.40531.512st -71251.92502.1250
2.25002.45002.65002.85003.2s00
7.057.12
7.237.34
7.477.64
7.858.138.328.70
9.109.60
10.00t 0.40
11.2s12.1013.7015.40t 7.00
18.0019.6021.2022.8026.00
0.287 s00.38000
0.502500.63750
o.79't791.00179
1.2s6301.601301.841302.3"t630
2.790623.415623.915624.41562
s.478626.540628.54062
r 0.6656212.66562
13.9r56215"915 6217.9156219.9156223.91s62
€
NOTES:(1) The basic dimensions of the American National standard raper Pipe Thread are given in inches to four or five decimal prac€s. whire thisimplies a greater degree of preci5ion than is ordinarily attained. these dimensions are the basis of gage dimensions and are so expressed for thepurpose of eliminating errors in computations.(2) Also length of thin ring gage and rength.from gaging notch ro smat end of prug gage.(3) Also pitch diameter at gaging notch (handtigtrt planel.{4) Also lengrh of plug gage.
e
AN AMERICAN NATIONAL STANDARDPIPE THREADS, GENERAL PURPOSE (INCHI ANSUASME 81.2O.1.1983
TABLE 2 BASIC DTMENSIONS OF AMERICAN NATIONAL STANDARD TAPER PIPE THREAD, NPTI (CONT'D)
{5} The length t5 from the end of the pipe determines the plane beyond which the thread form is incomplete at the crest- The next two ihreadsare complete at the root. At this plane the cone formed by the crests of the thread intersects the cylinder forming the external surface o{ thepipe. L5 = Lz -2p.
(6) Given as information for use in selecting tap drills. (See Appendix).(7) Military Specification MIL-P-7105 gives the wrench makeup as three threads for sizes 3 and smaller. The €t dimensions are as follows:
Nominal pipe size 2rl = 2.696019 and size 3 = 3.31719; sizes 2 ard srnaller same as above, col. 16"
{8} Reference dimension.
Length, L1 Planeto L2 Plans
External ThreadLz - Lrl
Wrenci lt/hkeup Length.fortnternal Thread?
Vanish Threadtn
OvErall8Length
ExternalThread
lLq)
Nominhl CompleteExtornal Threads5
Heightof
Thread(n)
I ncreasein Diam./
Thread(0.062s/n)
Basic6Minor Diam"
.t SmallEnd of
Pipa (Ko)PipeSize
Lengtl lLrl Diam.(Frl
Length(Ls )
Diam.{€s Itn. Thread ln. Thread tn- Thread
1 12 13 14 t5 16 17 18 19 20 21 22 23 24
lo7"
t,ln
I
rltl/z2
2th
,y2
5
6
8
1012
It/t6Y"
14 0.D.16 0.D.i 8 0.D.20 0.D.24 0.D.
0.10.1 1
0"1 024
0.1 7400.r 678
o.21370.2067
0.28280.28680.30350.3205
0.4s550.43400.42900.4s60
0.46930.55450.64950.71500.7650
0.68800.6 3800.65000.72500.8750
2.732.76
3.t 33.02
2.992.89
3.643-473.433.65
3.253.303.493.69
3.7 S
4.44s.205.726-12
5-505.105.205.807.00
0.1 111
0.1 It10"r 6670.1 667:1,--i6.21430-2143
o.26090.26090.26090.2609
0.25000.25000.25000.2s00
0.25000.25000.25000.25000.2500
0.25000.25000-25000.25000.2500
3
3
3
3
3
3
3
3
3
3
2
2
2
2
'2
2
2
2
?
2
2
2
2
2
o.264240.35656
o.466970.601 60
o-7 45040.95429
1.r 97331.540831.779782.25272
2.703913.325003.82r 884.3 I 875
5.3751 1
6.430478.4179't
10-5296912.51719
r 3.759381 5.74688't7.73438
19.7218823.69688
0.12850.1 285
0.1 9280.1 928
0.24780.2478
0.30 r 7
0.30r 7
0.30170.301 7
0.43370.43370.43310.4337
0.43370.43310.43370.43370.4331
0.4337o.43370.43370.43370.4337
3.473.47
3.473.47
3.473-47
3.413.473.413.47
3.473.473.473.47
3.473.473-473.473.47
3.473-473.473.473.47
0.3896o.3924
0.59460.6006
0.78r s0.7935
0.98451.00851.02521.0582
1.sl121.6337r.68371.1337
1.84001.94622.146?2.3s812.5587
2-68372.88313.08373-28373.6837
0.1 8700.1 898
0.39090.4029
0.5089o.53290:54960.5826
0.88750-95001.00001.0500'l<l 5631.26251.46251.67501.8750
2.00002.20002.40002.60003.0000
o.2907o.2967
0.282810.37 537
0.495560.63056
0.78286
.0.99286
1.245431.590431.830432-30543
2.775003.400003.900004.40000
5.463006.525008.5 2500
r 0-550001 2.65000
13.900001 5.90000I 7.9000019.9000023.90000
0.029630,02963
o.o4444o.04444
0.057140.057't 4
0.069570.069570.0695 7
0.06957
0.1 000000.1 000000.r 000000.1 00000
0.1 000000.1 000000.1 000000.r 000000.1 00000
0.1 000000.1 000000.r 000000.1 000000.1 00000
0.002310.00231
0.0034;0.0034;
0.0044(0.0044(
0.0054:0.0054:0.0054:0.0054:
0.0078'0.0078'0.0078'0.o078'
0.00780.0078'0.00780.00780.0078
0.00780.00780.00780_0078
0.0078
0.24'.t60.3339
o.43290.s676
0.70130.91 05
't.14411.487 61.72652.1995
2.61953.24063.737 5
4"2344
5"29076.34618.33 36
10.445312.4128
13.675015.66251 7.650019.637 5
23-6125
AN AMER ICAN NATIONAL STANDARDPIPE THREADS, GENERAL PURPOSE (INCHI
The illustrbtion shows standard designfor sizes 2'inch and smaller. Largersizes are of slightly diflerent designs.
ANS|/ASME 81.20.r-1983
Basic Size Max. Size Min. Size
Pluggage
Taper of I
thread 1 in 16measured ondiametet
L1eo-__!
FIG" 4 NPT STANDARD TAPER PIPE THREADPLUG AND RING GAGES
Basic Size Max. Size
FIG.7 GAGING INTERNAL TAPER
FIG.6 GAGING EXTERNAL TAPER THREADSWITH RING GAGE
(0,
0.1 16p
Roots sharpor undercut(form optional)
Roors must clear O.O3glp flat i
FIG" 5 SUGGESTED FORM OF GAGE THREADMin. Size
THREADS
One turn large
Flush
Crests rruncateO pdr Z.t.t
l4
tI