1 1/4-11.5 NPSH NPSH (pipe-size hose) External Thread Specifications
1 1/4-11.5NPSH EXT
ASMESTD: ASME B1.20.7SOURCE: Table 2 · p. 5TYPE: External (bolt/screw)CLASS: StdSERIES: NPSH (pipe-size hose)
Major diameter
1.6399 – 1.6229
max – min
Pitch diameter
1.5834 – 1.5749
max – min
Minor diameter
1.5269 – 1.5059
max – min
Pitch
0.08696
11.5 threads per inch
Thread profile
1 1/4-11.5NPSH 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
| Dimension | Basic | Max | Min | Tolerance |
|---|---|---|---|---|
| Major diameter dPara. 3.1: tolerance = 2 × PD tolerance | 1.6499 | 1.6399 | 1.6229 | 0.0170 |
| Pitch diameter d2 | 1.5934 | 1.5834 | 1.5749 | 0.0085 |
| Minor diameter d1Max printed; min is a reference value | 1.5369 | 1.5269 | 1.5059ref. | 0.0211ref. |
| Allowance es | 0.0100 |
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
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_1/4
- Mating member of the same designation
- 1 1/4-11.5NPSH 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
- 1° 00′
- 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 9/32; OD 1 5/8; L 5/8; l 5/32
- Inside diameter of the nipple C
- 1.28125 in
- Approximate OD of the external thread OD
- 1.62500 in
- Length of the nipple L
- 0.62500 in
- Pilot length l
- 0.15625 in
Ring gages (Table 6)
- GO pitch max / min
- 1.5834 / 1.5830 in
- GO minor max / min
- 1.5369 / 1.5363 in
- NOT GO pitch max / min
- 1.5753 / 1.5749 in
- NOT GO minor max / min
- 1.5567 / 1.5561 in
- Z GO major max / min
- 1.63990 / 1.63974 in
- Z NOT GO major max / min
- 1.62306 / 1.62290 in
Setting plugs (Table 8) and plug gages (Table 7)
- GO truncated major max / min
- 1.6266 / 1.6260 in
- GO full major max / min
- 1.6405 / 1.6399 in
- GO pitch max / min
- 1.5834 / 1.5830 in
- NOT GO truncated major max / min
- 1.6126 / 1.6210 in
- NOT GO pitch max / min
- 1.5753 / 1.5749 in
Notes
- Printed value kept. Misprint: Table 8 col 8 (p. 11), 1 1/4-11.5NPSH, printed NOT GO truncated major max 1.6126 / min 1.6210; expected min 1.6120. Root radius and tensile stress area are not given in the standard.
- Table 8 col 8 (p. 11), 1 1/4-11.5NPSH: printed NOT GO truncated major max 1.6126 / min 1.6210; expected min 1.6120
Mates
1 1/4-11.5NPSH 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
All values for 1 1/4-11.5NPSH EXTevery column of the workbook row
| Designation | 1 1/4-11.5NPSH EXT |
|---|---|
| Decimal / alternate designation | 1.2500-11.5NPSH EXT |
| Threads per inch | 11.5 |
| Thread form | NPSH |
| Series | NPSH |
| Series name | Hose to pipe thread (NPSH) |
| External / internal | External |
| Class | Std |
| Nominal size of hose | 1 1/4 |
| Pitch P (in.) | 0.08696 |
| Basic major dia D (in.) | 1.6499 |
| Size category | Standard sizes (Tables 1-8) |
| Source table | Table 2 |
| Printed page | 5 |
| Major dia max (in.) | 1.6399 |
| Major dia min (in.) | 1.6229 |
| Major dia tolerance (in.) | 0.0170 |
| Allowance es (in.) | 0.0100 |
| Basic pitch dia D2 (in.) | 1.5934 |
| Pitch dia max (in.) | 1.5834 |
| Pitch dia min (in.) | 1.5749 |
| PD tolerance (in.) | 0.0085 |
| Basic minor dia D1 (in.) | 1.5369 |
| Minor dia max (in.) | 1.5269 |
| Minor dia min (in.) | 1.5059 |
| Minor dia tolerance (in.) | 0.0211 |
| Major dia status | Toleranced (para. 3.1: tolerance = 2 x PD tolerance) |
| Minor dia status | Maximum 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) | 0.9952 |
| Lead angle (deg min) | 1° 00′ |
| 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.) | 1.639900 |
| Sweep cut: tip diameter (in.) | 1.526900 |
| Sweep cut: depth (in.) | 0.056500 |
| Sweep cut: profile width at start diameter (in.) | 0.076110 |
| Crest flat as modelled (in.) | 0.010847 |
| Taper | none (straight thread) |
| Service | Steam, air, water, and all other hose connections to be made up with standard pipe threads |
| Mating group (compatible designations) | NPSH-1_1/4 |
| Mating member of the same designation | 1 1/4-11.5NPSH INT |
| Other designations in the mating group | none (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 printed | C 1 9/32; OD 1 5/8; L 5/8; l 5/32 |
| Table 4: C inside dia of nipple (in.) | 1.28125 |
| Table 4: approx OD of external thread (in.) | 1.62500 |
| 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.) | 1.5834 |
| Table 6 ring gage: GO pitch min (in.) | 1.5830 |
| Table 6 ring gage: GO minor max (in.) | 1.5369 |
| Table 6 ring gage: GO minor min (in.) | 1.5363 |
| Table 6 ring gage: NOT GO pitch max (in.) | 1.5753 |
| Table 6 ring gage: NOT GO pitch min (in.) | 1.5749 |
| Table 6 ring gage: NOT GO minor max (in.) | 1.5567 |
| Table 6 ring gage: NOT GO minor min (in.) | 1.5561 |
| Table 6 ring gage: Z GO major max (in.) | 1.63990 |
| Table 6 ring gage: Z GO major min (in.) | 1.63974 |
| Table 6 ring gage: Z NOT GO major max (in.) | 1.62306 |
| Table 6 ring gage: Z NOT GO major min (in.) | 1.62290 |
| Table 8 setting plug: GO truncated major max (in.) | 1.6266 |
| Table 8 setting plug: GO truncated major min (in.) | 1.6260 |
| Table 8 setting plug: GO full major max (in.) | 1.6405 |
| Table 8 setting plug: GO full major min (in.) | 1.6399 |
| Table 8 setting plug: GO pitch max (in.) | 1.5834 |
| Table 8 setting plug: GO pitch min (in.) | 1.5830 |
| Table 8 setting plug: NOT GO truncated major max (in.) | 1.6126 |
| Table 8 setting plug: NOT GO truncated major min (in.) | 1.6210 |
| Table 8 setting plug: NOT GO full major max (in.) | 1.6405 |
| Table 8 setting plug: NOT GO full major min (in.) | 1.6399 |
| Table 8 setting plug: NOT GO pitch max (in.) | 1.5753 |
| Table 8 setting plug: NOT GO pitch min (in.) | 1.5749 |
| Table 8 setting plug: Full-form GO major max (in.) | 1.6405 |
| Table 8 setting plug: Full-form GO major min (in.) | 1.6399 |
| Table 8 setting plug: Full-form NOT GO major max (in.) | 1.6405 |
| Table 8 setting plug: Full-form NOT GO major min (in.) | 1.6399 |
| Check against formulas | Table 8 col 8 (p. 11), 1 1/4-11.5NPSH: printed NOT GO truncated major max 1.6126 / min 1.6210; expected min 1.6120 |
| Notes | Printed value kept. Misprint: Table 8 col 8 (p. 11), 1 1/4-11.5NPSH, printed NOT GO truncated major max 1.6126 / min 1.6210; expected min 1.6120. Root radius and tensile stress area are not given in the standard. |
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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.