3/8 inch pipe dimensions: OD and wall thickness by schedule
Deskely Completions team Singapore
A 3/8 inch pipe, NPS 3/8 or DN 10, has an outside diameter of 17.1 mm (0.675 inches) in every schedule. The nominal size is a name, not a measurement: the outside diameter is larger than 3/8 inch. The schedule sets the wall thickness, and with it the inside diameter and the weight.
The table gives every schedule listed for NPS 3/8 in ASME B36.10M and B36.19M, in mm and inches.
- Outside diameter: 17.1 mm (0.675 in), the same for every schedule.
- Schedule 40: 2.31 mm wall, 12.5 mm inside diameter.
- Schedule 80: 3.20 mm wall, 10.7 mm inside diameter.
- Metric equivalent: DN 10.
3/8 inch pipe dimensions by schedule
| Schedule | Wall mm (in) | ID mm (in) | kg/m (lb/ft) |
|---|---|---|---|
| Schedule 10S | 1.65 (0.065) | 13.80 (0.543) | 0.63 (0.42) |
| STD (standard) | 2.31 (0.091) | 12.48 (0.491) | 0.84 (0.57) |
| Schedule 40 | 2.31 (0.091) | 12.48 (0.491) | 0.84 (0.57) |
| XS (extra strong) | 3.20 (0.126) | 10.70 (0.421) | 1.10 (0.74) |
| Schedule 80 | 3.20 (0.126) | 10.70 (0.421) | 1.10 (0.74) |
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.
3/8 inch pipe outside diameter
The outside diameter of NPS 3/8 pipe is 17.1 mm, or 0.675 inches, whatever the schedule, so 3/8 inch fittings and flanges fit every wall thickness. In metric drawings and specifications the same size is called DN 10.
It is larger than 3/8 inch because, below NPS 14, the nominal size is a traditional name that once roughly matched the bore, not the outside.
Nearby sizes
- 1/4 inch pipe dimensions: OD 13.7 mm
- 1/2 inch pipe dimensions: OD 21.3 mm
Every size and schedule in one table: the pipe schedule chart.
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Frequently asked questions
What is the OD of 3/8 inch pipe?
17.1 mm (0.675 inches), the same for every schedule.
What is the wall thickness of 3/8 inch schedule 40 pipe?
2.31 mm (0.091 in), giving an inside diameter of 12.5 mm (0.491 in).
What is the wall thickness of 3/8 inch schedule 80 pipe?
3.20 mm (0.126 in), giving an inside diameter of 10.7 mm (0.421 in).
What is 3/8 inch pipe in DN?
DN 10.
How much does 3/8 inch schedule 40 pipe weigh?
0.84 kg/m (0.57 lb/ft) for plain-end carbon steel.
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