1/2-14 NPSH NPSH (pipe-size hose) External Thread Specifications

1/2-14NPSH EXT

ASMESTD: ASME B1.20.7SOURCE: Table 2 · p. 5TYPE: External (bolt/screw)CLASS: StdSERIES: NPSH (pipe-size hose)
Major diameter
0.8248 – 0.8108
max – min
Pitch diameter
0.7784 – 0.7714
max – min
Minor diameter
0.7320 – 0.7147
max – min
Pitch
0.07143
14 threads per inch

Thread profile

1/2-14NPSH EXT: external M profile with its tolerance zone, drawn to scaled = 0.832d2 = 0.786d1 = 0.740P = 0.0714360°30°crest 0.008929root 0.008929Major dia zone (crest)0.825 – 0.811 Td 0.014Pitch dia zone (flanks)0.778 – 0.771 Td2 0.007Root zone (minor dia)0.732 – 0.715Fundamental deviationes = −0.008 (allowance)H/80.0077333H/80.023198H/40.015465h = 5H/80.046394H0.061859thread axis, 0.416 in below the major radius (diameters shortened)MALE · external thread · 1/2-14NPSH EXT

1/2-14NPSH EXT: solid line = maximum material profile, dashed = minimum material, hatched = tolerance zone, grey dashed = basic profile. Drawn to scale; values in inches, diameters shortened.

Limits of size, class Std

DimensionBasicMaxMinTolerance
Major diameter dPara. 3.1: tolerance = 2 × PD tolerance0.83230.82480.81080.0140
Pitch diameter d20.78590.77840.77140.0070
Minor diameter d1Max printed; min is a reference value0.73950.73200.7147ref.0.0173ref.
Allowance es0.0075

Dimensions in inches. Values are those of the standard (ASME B1.20.7); calculated cells follow the standard’s formulas. Where the standard prints a value that differs from its formula, the printed value is shown with a note.

Tolerance zones relative to the basic size, inches

Tolerance zones relative to the basic sizezero line = basic size+ above · − belowd2es −0.008ei −0.015male pitch dia Stdes −0.008des −0.008ei −0.022male major dia (crest)es −0.008

Mating, gaging and dimensions

Mating member and fit at the limits

Service
Steam, air, water, and all other hose connections to be made up with standard pipe threads
Mating group (compatible designations)
NPSH-1/2
Mating member of the same designation
1/2-14NPSH INT
Other designations in the mating group
none (mates only with its own designation)
Minimum PD clearance (coupling min − nipple max)
0.0075 in
Maximum PD clearance (coupling max − nipple min)
0.0215 in
Minimum major dia clearance
0.0075 in
Minimum minor dia clearance
0.0075 in
Fit at the limits (PD)
clearance (always)

Lead, flank and profile

Lead variation ± (Table 5) ±δP
0.0020 in
Half-angle variation ± (Table 5) ±δα
1° 52′
Lead angle at the basic PD λ
1° 39′
Crest flat (basic P/8)
0.008929 in
Root flat (basic P/8)
0.008929 in
Extreme flat P/24 at minimum PD
0.002976 in
Root radius for the model (worn tool) r
0.007732 in

Table 4 dimensions (nipple and coupling)

As printed
C 17/32; OD 13/16; L 1/2; l 1/8
Inside diameter of the nipple C
0.53125 in
Approximate OD of the external thread OD
0.81250 in
Length of the nipple L
0.50000 in
Pilot length l
0.12500 in

Ring gages (Table 6)

GO pitch max / min
0.7784 / 0.7781 in
GO minor max / min
0.7395 / 0.7389 in
NOT GO pitch max / min
0.7717 / 0.7714 in
NOT GO minor max / min
0.7565 / 0.7559 in
Z GO major max / min
0.82480 / 0.82470 in
Z NOT GO major max / min
0.81090 / 0.81080 in

Setting plugs (Table 8) and plug gages (Table 7)

GO truncated major max / min
0.8133 / 0.8127 in
GO full major max / min
0.8254 / 0.8248 in
GO pitch max / min
0.7784 / 0.7781 in
NOT GO truncated major max / min
0.8023 / 0.8017 in
NOT GO pitch max / min
0.7717 / 0.7714 in

Notes

  • Root radius and tensile stress area are not given in the standard.

Mates

1/2-14NPSH EXT screws into a thread of the same standard at the same size and pitch. The standard mating internal thread is class Std. Check the fit with the standard pair →

Working out the mating options…

Different pitch or a different thread family never mate; the fit check runs over both tolerance zones.

Related thread sizes

Same diameter other pitch, and neighbouring sizes

→ 3/4-14 NPSH→ 1/2-14 NPSH internal
All values for 1/2-14NPSH EXTevery column of the workbook row
All values of the workbook row 1/2-14NPSH EXT
Designation1/2-14NPSH EXT
Decimal / alternate designation0.5000-14NPSH EXT
Threads per inch14
Thread formNPSH
SeriesNPSH
Series nameHose to pipe thread (NPSH)
External / internalExternal
ClassStd
Nominal size of hose1/2
Pitch P (in.)0.07143
Basic major dia D (in.)0.8323
Size categoryStandard sizes (Tables 1-8)
Source tableTable 2
Printed page5
Major dia max (in.)0.8248
Major dia min (in.)0.8108
Major dia tolerance (in.)0.0140
Allowance es (in.)0.0075
Basic pitch dia D2 (in.)0.7859
Pitch dia max (in.)0.7784
Pitch dia min (in.)0.7714
PD tolerance (in.)0.0070
Basic minor dia D1 (in.)0.7395
Minor dia max (in.)0.7320
Minor dia min (in.)0.7147
Minor dia tolerance (in.)0.0173
Major dia statusToleranced (para. 3.1: tolerance = 2 x PD tolerance)
Minor dia statusMaximum printed; minimum is a reference value (para. 3.1: P/24 flat at min PD)
Root radius max (in.)not given in the standard
Root radius min (in.)not given in the standard
Lead variation ± (in.) (Table 5)0.0020
Half-angle variation ± (Table 5)1° 52′
Lead variation from PD tol (calc) (in.)0.0020
Half-angle variation from PD tol (calc)1° 52′
Lead angle at basic PD (deg)1.6571
Lead angle (deg min)1° 39′
Tensile stress area As (sq in.)not given in the standard
Thread angle (deg)60
Flank angle (deg)30
Sharp V height H (in.)0.061859
Thread height h (in.)0.046394
Crest flat, basic P/8 (in.)0.008929
Root flat, basic P/8 (in.)0.008929
Extreme flat P/24 at minimum PD (in.)0.002976
Truncation of the P/8 flat from the sharp V, f = h/6 (in.)0.007732
Root radius for model (worn tool) (in.)0.007732
Sweep cut: start diameter (in.)0.824800
Sweep cut: tip diameter (in.)0.732000
Sweep cut: depth (in.)0.046400
Sweep cut: profile width at start diameter (in.)0.062507
Crest flat as modelled (in.)0.008922
Tapernone (straight thread)
ServiceSteam, air, water, and all other hose connections to be made up with standard pipe threads
Mating group (compatible designations)NPSH-1/2
Mating member of the same designation1/2-14NPSH INT
Other designations in the mating groupnone (mates only with its own designation)
Min PD clearance: coupling min PD - nipple max PD (in.)0.0075
Max PD clearance: coupling max PD - nipple min PD (in.)0.0215
Min major dia clearance: coupling min - nipple max (in.)0.0075
Min minor dia clearance: coupling min - nipple max (in.)0.0075
Fit at the limits (PD)clearance (always)
Table 4 lengths as printedC 17/32; OD 13/16; L 1/2; l 1/8
Table 4: C inside dia of nipple (in.)0.53125
Table 4: approx OD of external thread (in.)0.81250
Table 4: L length of nipple (in.)0.50000
Table 4: l pilot length (in.)0.12500
Table 6 ring gage: GO pitch max (in.)0.7784
Table 6 ring gage: GO pitch min (in.)0.7781
Table 6 ring gage: GO minor max (in.)0.7395
Table 6 ring gage: GO minor min (in.)0.7389
Table 6 ring gage: NOT GO pitch max (in.)0.7717
Table 6 ring gage: NOT GO pitch min (in.)0.7714
Table 6 ring gage: NOT GO minor max (in.)0.7565
Table 6 ring gage: NOT GO minor min (in.)0.7559
Table 6 ring gage: Z GO major max (in.)0.82480
Table 6 ring gage: Z GO major min (in.)0.82470
Table 6 ring gage: Z NOT GO major max (in.)0.81090
Table 6 ring gage: Z NOT GO major min (in.)0.81080
Table 8 setting plug: GO truncated major max (in.)0.8133
Table 8 setting plug: GO truncated major min (in.)0.8127
Table 8 setting plug: GO full major max (in.)0.8254
Table 8 setting plug: GO full major min (in.)0.8248
Table 8 setting plug: GO pitch max (in.)0.7784
Table 8 setting plug: GO pitch min (in.)0.7781
Table 8 setting plug: NOT GO truncated major max (in.)0.8023
Table 8 setting plug: NOT GO truncated major min (in.)0.8017
Table 8 setting plug: NOT GO full major max (in.)0.8254
Table 8 setting plug: NOT GO full major min (in.)0.8248
Table 8 setting plug: NOT GO pitch max (in.)0.7717
Table 8 setting plug: NOT GO pitch min (in.)0.7714
Table 8 setting plug: Full-form GO major max (in.)0.8254
Table 8 setting plug: Full-form GO major min (in.)0.8248
Table 8 setting plug: Full-form NOT GO major max (in.)0.8254
Table 8 setting plug: Full-form NOT GO major min (in.)0.8248
Check against formulasOK
NotesRoot radius and tensile stress area are not given in the standard.

Related tools

ASME B1.20.7: Hose Coupling Screw Threads, Inch. Source: workbook data (2026-10-10). Confirm against your licensed copy of the standard before use.