NPS 1 1/4 Extra Strong (XS) Pipe
1.660 in (42.2 mm) outside diameter on a 0.191 in (4.9 mm) wall, giving a 1.278 in (32.5 mm) bore and 3.00 lb/ft (4.46 kg/m) empty. ASME B36.10M.
- Nominal size
- NPS 1 1/4 (DN 32)
- Schedule
- Extra Strong (XS)
- Outside diameter
- 1.660 in (42.2 mm)
- Wall thickness
- 0.191 in (4.9 mm)
- Inside diameter
- 1.278 in (32.5 mm)
- Weight, empty
- 3.00 lb/ft (4.46 kg/m)
- Weight, water filled
- 3.55 lb/ft (5.29 kg/m)
- Flow area
- 1.283 in² (828 mm²)
In NPS 1 1/4 this wall thickness is also designated Schedule 80. That is the same pipe under another name, not a different product — but the coincidence is specific to this size and does not hold across the range.
Every schedule in NPS 1 1/4
Dimensions are given in inches, with the millimetre equivalent beneath in grey.
| Schedule | Wall thickness | Inside diameter | Weight, empty | Water (US gal/ft) |
|---|---|---|---|---|
| Sch 5 | 0.0651.65 mm | 1.53038.86 mm | 1.111.65 kg/m | 0.096 |
| Sch 10 | 0.1092.77 mm | 1.44236.63 mm | 1.812.69 kg/m | 0.085 |
| Sch 40 | 0.1403.56 mm | 1.38035.05 mm | 2.273.38 kg/m | 0.078 |
| STD | 0.1403.56 mm | 1.38035.05 mm | 2.273.38 kg/m | 0.078 |
| Sch 80 | 0.1914.85 mm | 1.27832.46 mm | 3.004.46 kg/m | 0.067 |
| XS this page | 0.1914.85 mm | 1.27832.46 mm | 3.004.46 kg/m | 0.067 |
| Sch 160 | 0.2506.35 mm | 1.16029.46 mm | 3.765.60 kg/m | 0.055 |
| XXS | 0.3829.70 mm | 0.89622.76 mm | 5.217.76 kg/m | 0.033 |
Weight is plain-end carbon steel, w = 10.6802 × t × (OD − t) lb/ft.
Flanges for NPS 1 1/4 pipe
Flange dimensions are set by NPS and pressure class, not by schedule, so every flange below fits this pipe. The exception is the weld neck: its bore is machined to the pipe it is welded to, which for Extra Strong (XS) means 1.278 in (32.5 mm). Order the flange to the schedule or the bores will not line up at the weld.
| Class | Flange OD | Thickness | Bolt circle | Bolting |
|---|---|---|---|---|
| Class 150 | 4.62117.35 mm | 0.6215.75 mm | 3.5088.90 mm | 4 × 1/2 in |
| Class 300 | 5.25133.35 mm | 0.7519.05 mm | 3.8898.55 mm | 4 × 5/8 in |
| Class 400 | 5.25133.35 mm | 0.8120.57 mm | 3.8898.55 mm | 4 × 5/8 in |
| Class 600 | 5.25133.35 mm | 0.8120.57 mm | 3.8898.55 mm | 4 × 5/8 in |
| Class 900 | 6.25158.75 mm | 1.1228.45 mm | 4.38111.25 mm | 4 × 7/8 in |
| Class 1500 | 6.25158.75 mm | 1.1228.45 mm | 4.38111.25 mm | 4 × 7/8 in |
| Class 2500 | 7.25184.15 mm | 1.5038.10 mm | 5.12130.05 mm | 4 × 1 in |
Fittings for NPS 1 1/4 pipe
ASME B16.9 dimensions come from NPS alone, so these figures hold for Extra Strong (XS) exactly as they do for every other schedule in the size. Only the wall thickness has to be ordered to match.
| Fitting | Dimension | NPS 1 1/4 |
|---|---|---|
| 90° Long Radius Elbow | Centre-to-end A | 1.8847.75 mm |
| 90° Short Radius Elbow | Centre-to-end A | 1.2531.75 mm |
| 45° Long Radius Elbow | Centre-to-end B | 1.0025.40 mm |
| Straight Tee | Centre-to-end C and M | 1.8847.75 mm |
| Reducing Tee | Run centre-to-end C | 1.8847.75 mm |
| Concentric Reducer | End-to-end H | 2.0050.80 mm |
| Eccentric Reducer | End-to-end H | 2.0050.80 mm |
| Cap | Length E | 1.5038.10 mm |
Common questions
What is the inside diameter of NPS 1 1/4 extra strong (xs) pipe?
1.278 in (32.5 mm). The outside diameter is fixed at 1.660 in (42.2 mm) by ASME B36.10M, and the 0.191 in (4.9 mm) wall takes 0.382 in off it — 0.191 in from each side — leaving that bore.
How much does NPS 1 1/4 extra strong (xs) pipe weigh?
3.00 lb/ft (4.46 kg/m) empty, as plain-end carbon steel. Full of water it comes to 3.55 lb/ft (5.29 kg/m), because the bore holds 0.067 US gallons per foot. One short ton of this pipe is about 667 ft.
Does NPS 1 1/4 extra strong (xs) pipe use special flanges or fittings?
No. Flanges and buttweld fittings are dimensioned from NPS, so NPS 1 1/4 hardware fits this pipe in any schedule. The one thing that does follow the schedule is the bore of a weld neck flange or a fitting end prep, which has to be 1.278 in (32.5 mm) to match.