NPS 12 Schedule 120 Pipe
12.750 in (323.8 mm) outside diameter on a 1.000 in (25.4 mm) wall, giving a 10.750 in (273.1 mm) bore and 125.49 lb/ft (186.75 kg/m) empty. ASME B36.10M.
- Nominal size
- NPS 12 (DN 300)
- Schedule
- Schedule 120
- Outside diameter
- 12.750 in (323.8 mm)
- Wall thickness
- 1.000 in (25.4 mm)
- Inside diameter
- 10.750 in (273.1 mm)
- Weight, empty
- 125.49 lb/ft (186.75 kg/m)
- Weight, water filled
- 164.84 lb/ft (245.31 kg/m)
- Flow area
- 90.763 in² (58556 mm²)
In NPS 12 this wall thickness is also designated Double Extra Strong (XXS). 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 12
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 | 0.1563.96 mm | 12.438315.93 mm | 20.9831.23 kg/m | 6.312 |
| Sch 10 | 0.1804.57 mm | 12.390314.71 mm | 24.1735.96 kg/m | 6.263 |
| Sch 20 | 0.2506.35 mm | 12.250311.15 mm | 33.3849.67 kg/m | 6.123 |
| Sch 30 | 0.3308.38 mm | 12.090307.09 mm | 43.7765.14 kg/m | 5.964 |
| Sch 40 | 0.40610.31 mm | 11.938303.23 mm | 53.5379.65 kg/m | 5.815 |
| STD | 0.3759.52 mm | 12.000304.80 mm | 49.5673.76 kg/m | 5.875 |
| Sch 60 | 0.56214.27 mm | 11.626295.30 mm | 73.16108.87 kg/m | 5.515 |
| Sch 80 | 0.68817.48 mm | 11.374288.90 mm | 88.63131.90 kg/m | 5.278 |
| XS | 0.50012.70 mm | 11.750298.45 mm | 65.4297.35 kg/m | 5.633 |
| Sch 100 | 0.84421.44 mm | 11.062280.97 mm | 107.32159.71 kg/m | 4.993 |
| Sch 120 this page | 1.00025.40 mm | 10.750273.05 mm | 125.49186.75 kg/m | 4.715 |
| Sch 140 | 1.12528.57 mm | 10.500266.70 mm | 139.68207.86 kg/m | 4.498 |
| Sch 160 | 1.31233.32 mm | 10.126257.20 mm | 160.27238.51 kg/m | 4.183 |
| XXS | 1.00025.40 mm | 10.750273.05 mm | 125.49186.75 kg/m | 4.715 |
Weight is plain-end carbon steel, w = 10.6802 × t × (OD − t) lb/ft.
Flanges for NPS 12 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 120 means 10.750 in (273.1 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 | 19.00482.60 mm | 1.2531.75 mm | 17.00431.80 mm | 12 × 7/8 in |
| Class 300 | 20.50520.70 mm | 2.0050.80 mm | 17.75450.85 mm | 16 × 1 1/8 in |
| Class 400 | 20.50520.70 mm | 2.2557.15 mm | 17.75450.85 mm | 16 × 1 1/4 in |
| Class 600 | 22.00558.80 mm | 2.6266.55 mm | 19.25488.95 mm | 20 × 1 1/4 in |
| Class 900 | 24.00609.60 mm | 3.1279.25 mm | 21.00533.40 mm | 20 × 1 3/8 in |
| Class 1500 | 26.50673.10 mm | 4.88123.95 mm | 22.50571.50 mm | 16 × 2 in |
| Class 2500 | 30.00762.00 mm | 7.25184.15 mm | 24.38619.25 mm | 12 × 2 3/4 in |
Fittings for NPS 12 pipe
ASME B16.9 dimensions come from NPS alone, so these figures hold for Schedule 120 exactly as they do for every other schedule in the size. Only the wall thickness has to be ordered to match.
| Fitting | Dimension | NPS 12 |
|---|---|---|
| 90° Long Radius Elbow | Centre-to-end A | 18.00457.20 mm |
| 90° Short Radius Elbow | Centre-to-end A | 12.00304.80 mm |
| 45° Long Radius Elbow | Centre-to-end B | 7.50190.50 mm |
| Straight Tee | Centre-to-end C and M | 10.00254.00 mm |
| Reducing Tee | Run centre-to-end C | 10.00254.00 mm |
| Concentric Reducer | End-to-end H | 8.00203.20 mm |
| Eccentric Reducer | End-to-end H | 8.00203.20 mm |
| Cap | Length E | 6.00152.40 mm |
Common questions
What is the inside diameter of NPS 12 schedule 120 pipe?
10.750 in (273.1 mm). The outside diameter is fixed at 12.750 in (323.8 mm) by ASME B36.10M, and the 1.000 in (25.4 mm) wall takes 2.000 in off it — 1.000 in from each side — leaving that bore.
How much does NPS 12 schedule 120 pipe weigh?
125.49 lb/ft (186.75 kg/m) empty, as plain-end carbon steel. Full of water it comes to 164.84 lb/ft (245.31 kg/m), because the bore holds 4.715 US gallons per foot. One short ton of this pipe is about 16 ft.
Does NPS 12 schedule 120 pipe use special flanges or fittings?
No. Flanges and buttweld fittings are dimensioned from NPS, so NPS 12 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 10.750 in (273.1 mm) to match.