12 inch pipe dimensions: OD and wall thickness by schedule
Deskely Completions team Singapore
A 12 inch pipe, NPS 12 or DN 300, has an outside diameter of 323.8 mm (12.750 inches) in every schedule. The nominal size is a name, not a measurement: the outside diameter is larger than 12 inch. The schedule sets the wall thickness, and with it the inside diameter and the weight.
The table gives every schedule listed for NPS 12 in ASME B36.10M and B36.19M, in mm and inches.
- Outside diameter: 323.8 mm (12.750 in), the same for every schedule.
- Schedule 40: 10.31 mm wall, 303.2 mm inside diameter.
- Schedule 80: 17.48 mm wall, 288.8 mm inside diameter.
- Metric equivalent: DN 300.
12 inch pipe dimensions by schedule
| Schedule | Wall mm (in) | ID mm (in) | kg/m (lb/ft) |
|---|---|---|---|
| Schedule 5S | 3.96 (0.156) | 315.88 (12.436) | 31.24 (20.99) |
| Schedule 10S | 4.57 (0.180) | 314.66 (12.388) | 35.98 (24.18) |
| Schedule 20 | 6.35 (0.250) | 311.10 (12.248) | 49.71 (33.41) |
| Schedule 30 | 8.38 (0.330) | 307.04 (12.088) | 65.19 (43.80) |
| STD (standard) | 9.53 (0.375) | 304.74 (11.998) | 73.86 (49.63) |
| Schedule 40 | 10.31 (0.406) | 303.18 (11.936) | 79.71 (53.56) |
| Schedule 60 | 14.27 (0.562) | 295.26 (11.624) | 108.93 (73.20) |
| XS (extra strong) | 12.70 (0.500) | 298.40 (11.748) | 97.44 (65.47) |
| Schedule 80 | 17.48 (0.688) | 288.84 (11.372) | 132.05 (88.73) |
| Schedule 100 | 21.44 (0.844) | 280.92 (11.060) | 159.87 (107.43) |
| Schedule 120 | 25.40 (1.000) | 273.00 (10.748) | 186.92 (125.60) |
| Schedule 140 | 28.58 (1.125) | 266.64 (10.498) | 208.08 (139.82) |
| Schedule 160 | 33.32 (1.312) | 257.16 (10.124) | 238.69 (160.39) |
| XXS (double extra strong) | 25.40 (1.000) | 273.00 (10.748) | 186.92 (125.60) |
Nominal dimensions. Weights are for plain-end carbon steel; stainless steel is about 2 percent heavier. Mill tolerances apply, and your project pipe specification takes precedence.
12 inch pipe outside diameter
The outside diameter of NPS 12 pipe is 323.8 mm, or 12.750 inches, whatever the schedule, so 12 inch fittings and flanges fit every wall thickness. In metric drawings and specifications the same size is called DN 300.
It is larger than 12 inch because, below NPS 14, the nominal size is a traditional name that once roughly matched the bore, not the outside.
Nearby sizes
- 10 inch pipe dimensions: OD 273.1 mm
- 14 inch pipe dimensions: OD 355.6 mm
Every size and schedule in one table: the pipe schedule chart.
The Deskely products for this
Frequently asked questions
What is the OD of 12 inch pipe?
323.8 mm (12.750 inches), the same for every schedule.
What is the wall thickness of 12 inch schedule 40 pipe?
10.31 mm (0.406 in), giving an inside diameter of 303.2 mm (11.936 in).
What is the wall thickness of 12 inch schedule 80 pipe?
17.48 mm (0.688 in), giving an inside diameter of 288.8 mm (11.372 in).
What is 12 inch pipe in DN?
DN 300.
How much does 12 inch schedule 40 pipe weigh?
79.71 kg/m (53.56 lb/ft) for plain-end carbon steel.
- In production since 2014
- Thousands of daily users
- On MODEC FPSO projects since 2016