NPS 1 Schedule 40 Pipe
1.315 in (33.4 mm) outside diameter on a 0.133 in (3.4 mm) wall, giving a 1.049 in (26.6 mm) bore and 1.68 lb/ft (2.50 kg/m) empty. ASME B36.10M.
- Nominal size
- NPS 1 (DN 25)
- Schedule
- Schedule 40
- Outside diameter
- 1.315 in (33.4 mm)
- Wall thickness
- 0.133 in (3.4 mm)
- Inside diameter
- 1.049 in (26.6 mm)
- Weight, empty
- 1.68 lb/ft (2.50 kg/m)
- Weight, water filled
- 2.05 lb/ft (3.06 kg/m)
- Flow area
- 0.864 in² (558 mm²)
In NPS 1 this wall thickness is also designated Standard (STD). 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
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 | 1.18530.10 mm | 0.871.29 kg/m | 0.057 |
| Sch 10 | 0.1092.77 mm | 1.09727.86 mm | 1.402.09 kg/m | 0.049 |
| Sch 40 this page | 0.1333.38 mm | 1.04926.64 mm | 1.682.50 kg/m | 0.045 |
| STD | 0.1333.38 mm | 1.04926.64 mm | 1.682.50 kg/m | 0.045 |
| Sch 80 | 0.1794.55 mm | 0.95724.31 mm | 2.173.23 kg/m | 0.037 |
| XS | 0.1794.55 mm | 0.95724.31 mm | 2.173.23 kg/m | 0.037 |
| Sch 160 | 0.2506.35 mm | 0.81520.70 mm | 2.844.23 kg/m | 0.027 |
| XXS | 0.3589.09 mm | 0.59915.21 mm | 3.665.45 kg/m | 0.015 |
Weight is plain-end carbon steel, w = 10.6802 × t × (OD − t) lb/ft.
Flanges for NPS 1 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 Schedule 40 means 1.049 in (26.6 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 | 4.25107.95 mm | 0.5614.22 mm | 3.1279.25 mm | 4 × 1/2 in |
| Class 300 | 4.88123.95 mm | 0.6917.53 mm | 3.5088.90 mm | 4 × 5/8 in |
| Class 400 | 4.88123.95 mm | 0.6917.53 mm | 3.5088.90 mm | 4 × 5/8 in |
| Class 600 | 4.88123.95 mm | 0.6917.53 mm | 3.5088.90 mm | 4 × 5/8 in |
| Class 900 | 5.88149.35 mm | 1.1228.45 mm | 4.00101.60 mm | 4 × 7/8 in |
| Class 1500 | 5.88149.35 mm | 1.1228.45 mm | 4.00101.60 mm | 4 × 7/8 in |
| Class 2500 | 6.25158.75 mm | 1.3835.05 mm | 4.25107.95 mm | 4 × 7/8 in |
Fittings for NPS 1 pipe
ASME B16.9 dimensions come from NPS alone, so these figures hold for Schedule 40 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 |
|---|---|---|
| 90° Long Radius Elbow | Centre-to-end A | 1.5038.10 mm |
| 90° Short Radius Elbow | Centre-to-end A | 1.0025.40 mm |
| 45° Long Radius Elbow | Centre-to-end B | 0.8822.35 mm |
| Straight Tee | Centre-to-end C and M | 1.5038.10 mm |
| Reducing Tee | Run centre-to-end C | 1.5038.10 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 schedule 40 pipe?
1.049 in (26.6 mm). The outside diameter is fixed at 1.315 in (33.4 mm) by ASME B36.10M, and the 0.133 in (3.4 mm) wall takes 0.266 in off it — 0.133 in from each side — leaving that bore.
How much does NPS 1 schedule 40 pipe weigh?
1.68 lb/ft (2.50 kg/m) empty, as plain-end carbon steel. Full of water it comes to 2.05 lb/ft (3.06 kg/m), because the bore holds 0.045 US gallons per foot. One short ton of this pipe is about 1191 ft.
Does NPS 1 schedule 40 pipe use special flanges or fittings?
No. Flanges and buttweld fittings are dimensioned from NPS, so NPS 1 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 1.049 in (26.6 mm) to match.