1 1/2-11.5 NPSH NPSH (pipe-size hose) External Thread Specifications

1 1/2-11.5NPSH EXT

ASMESTD: ASME B1.20.7SOURCE: Table 2 · p. 5TYPE: External (bolt/screw)CLASS: StdSERIES: NPSH (pipe-size hose)
Major diameter
1.8788 – 1.8618
max – min
Pitch diameter
1.8223 – 1.8138
max – min
Minor diameter
1.7658 – 1.7448
max – min
Pitch
0.08696
11.5 threads per inch

Thread profile

1 1/2-11.5NPSH EXT: external M profile with its tolerance zone, drawn to scaled = 1.889d2 = 1.832d1 = 1.776P = 0.0869660°30°crest 0.010870root 0.010870Major dia zone (crest)1.879 – 1.862 Td 0.017Pitch dia zone (flanks)1.822 – 1.814 Td2 0.009Root zone (minor dia)1.766 – 1.745Fundamental deviationes = −0.010 (allowance)H/80.0094143H/80.028241H/40.018827h = 5H/80.056480H0.075307thread axis, 0.944 in below the major radius (diameters shortened)MALE · external thread · 1 1/2-11.5NPSH EXT

1 1/2-11.5NPSH 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 tolerance1.88881.87881.86180.0170
Pitch diameter d21.83231.82231.81380.0085
Minor diameter d1Max printed; min is a reference value1.77581.76581.7448ref.0.0211ref.
Allowance es0.0100

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 −0.010ei −0.018male pitch dia Stdes −0.010des −0.010ei −0.027male major dia (crest)es −0.010

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_1/2
Mating member of the same designation
1 1/2-11.5NPSH INT
Other designations in the mating group
none (mates only with its own designation)
Minimum PD clearance (coupling min − nipple max)
0.0100 in
Maximum PD clearance (coupling max − nipple min)
0.0270 in
Minimum major dia clearance
0.0100 in
Minimum minor dia clearance
0.0100 in
Fit at the limits (PD)
clearance (always)

Lead, flank and profile

Lead variation ± (Table 5) ±δP
0.0025 in
Half-angle variation ± (Table 5) ±δα
1° 52′
Lead angle at the basic PD λ
0° 52′
Crest flat (basic P/8)
0.010870 in
Root flat (basic P/8)
0.010870 in
Extreme flat P/24 at minimum PD
0.003623 in
Root radius for the model (worn tool) r
0.009413 in

Table 4 dimensions (nipple and coupling)

As printed
C 1 17/32; OD 1 7/8; L 5/8; l 5/32
Inside diameter of the nipple C
1.53125 in
Approximate OD of the external thread OD
1.87500 in
Length of the nipple L
0.62500 in
Pilot length l
0.15625 in

Ring gages (Table 6)

GO pitch max / min
1.8223 / 1.8219 in
GO minor max / min
1.7758 / 1.7752 in
NOT GO pitch max / min
1.8142 / 1.8138 in
NOT GO minor max / min
1.7956 / 1.7950 in
Z GO major max / min
1.87880 / 1.87864 in
Z NOT GO major max / min
1.86196 / 1.86180 in

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

GO truncated major max / min
1.8655 / 1.8649 in
GO full major max / min
1.8794 / 1.8788 in
GO pitch max / min
1.8223 / 1.8219 in
NOT GO truncated major max / min
1.8515 / 1.8509 in
NOT GO pitch max / min
1.8142 / 1.8138 in

Notes

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

Mates

1 1/2-11.5NPSH 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

→ 1 1/4-11.5 NPSH→ 2-11.5 NPSH→ 1 1/2-11.5 NPSH internal
All values for 1 1/2-11.5NPSH EXTevery column of the workbook row
All values of the workbook row 1 1/2-11.5NPSH EXT
Designation1 1/2-11.5NPSH EXT
Decimal / alternate designation1.5000-11.5NPSH EXT
Threads per inch11.5
Thread formNPSH
SeriesNPSH
Series nameHose to pipe thread (NPSH)
External / internalExternal
ClassStd
Nominal size of hose1 1/2
Pitch P (in.)0.08696
Basic major dia D (in.)1.8888
Size categoryStandard sizes (Tables 1-8)
Source tableTable 2
Printed page5
Major dia max (in.)1.8788
Major dia min (in.)1.8618
Major dia tolerance (in.)0.0170
Allowance es (in.)0.0100
Basic pitch dia D2 (in.)1.8323
Pitch dia max (in.)1.8223
Pitch dia min (in.)1.8138
PD tolerance (in.)0.0085
Basic minor dia D1 (in.)1.7758
Minor dia max (in.)1.7658
Minor dia min (in.)1.7448
Minor dia tolerance (in.)0.0211
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)0.0025
Half-angle variation ± (Table 5)1° 52′
Lead variation from PD tol (calc) (in.)0.0025
Half-angle variation from PD tol (calc)1° 52′
Lead angle at basic PD (deg)0.8655
Lead angle (deg min)0° 52′
Tensile stress area As (sq in.)not given in the standard
Thread angle (deg)60
Flank angle (deg)30
Sharp V height H (in.)0.075307
Thread height h (in.)0.056480
Crest flat, basic P/8 (in.)0.010870
Root flat, basic P/8 (in.)0.010870
Extreme flat P/24 at minimum PD (in.)0.003623
Truncation of the P/8 flat from the sharp V, f = h/6 (in.)0.009413
Root radius for model (worn tool) (in.)0.009413
Sweep cut: start diameter (in.)1.878800
Sweep cut: tip diameter (in.)1.765800
Sweep cut: depth (in.)0.056500
Sweep cut: profile width at start diameter (in.)0.076110
Crest flat as modelled (in.)0.010847
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_1/2
Mating member of the same designation1 1/2-11.5NPSH INT
Other designations in the mating groupnone (mates only with its own designation)
Min PD clearance: coupling min PD - nipple max PD (in.)0.0100
Max PD clearance: coupling max PD - nipple min PD (in.)0.0270
Min major dia clearance: coupling min - nipple max (in.)0.0100
Min minor dia clearance: coupling min - nipple max (in.)0.0100
Fit at the limits (PD)clearance (always)
Table 4 lengths as printedC 1 17/32; OD 1 7/8; L 5/8; l 5/32
Table 4: C inside dia of nipple (in.)1.53125
Table 4: approx OD of external thread (in.)1.87500
Table 4: L length of nipple (in.)0.62500
Table 4: l pilot length (in.)0.15625
Table 6 ring gage: GO pitch max (in.)1.8223
Table 6 ring gage: GO pitch min (in.)1.8219
Table 6 ring gage: GO minor max (in.)1.7758
Table 6 ring gage: GO minor min (in.)1.7752
Table 6 ring gage: NOT GO pitch max (in.)1.8142
Table 6 ring gage: NOT GO pitch min (in.)1.8138
Table 6 ring gage: NOT GO minor max (in.)1.7956
Table 6 ring gage: NOT GO minor min (in.)1.7950
Table 6 ring gage: Z GO major max (in.)1.87880
Table 6 ring gage: Z GO major min (in.)1.87864
Table 6 ring gage: Z NOT GO major max (in.)1.86196
Table 6 ring gage: Z NOT GO major min (in.)1.86180
Table 8 setting plug: GO truncated major max (in.)1.8655
Table 8 setting plug: GO truncated major min (in.)1.8649
Table 8 setting plug: GO full major max (in.)1.8794
Table 8 setting plug: GO full major min (in.)1.8788
Table 8 setting plug: GO pitch max (in.)1.8223
Table 8 setting plug: GO pitch min (in.)1.8219
Table 8 setting plug: NOT GO truncated major max (in.)1.8515
Table 8 setting plug: NOT GO truncated major min (in.)1.8509
Table 8 setting plug: NOT GO full major max (in.)1.8794
Table 8 setting plug: NOT GO full major min (in.)1.8788
Table 8 setting plug: NOT GO pitch max (in.)1.8142
Table 8 setting plug: NOT GO pitch min (in.)1.8138
Table 8 setting plug: Full-form GO major max (in.)1.8794
Table 8 setting plug: Full-form GO major min (in.)1.8788
Table 8 setting plug: Full-form NOT GO major max (in.)1.8794
Table 8 setting plug: Full-form NOT GO major min (in.)1.8788
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.