Use this page as a dimensional reference for Schedule 40 pipe 1 inch (DN25) when checking piping layouts, fabrication details, material takeoffs, or CAD models. The source data below identifies the nominal designation and provides the corresponding outside diameter, inside diameter, wall thickness, and weight information.
Remember that NPS 1 and DN25 are nominal size designations; neither label should be treated as the pipe’s directly measured outside or inside diameter. For selection and detailing, use the listed dimensions together with the applicable project specifications, material requirements, connection details, and engineering checks.
Schedule 40 pipe 1 inch (DN25) is a standard steel pipe size commonly used in piping design, fabrication, drafting, and engineering estimation work. This page provides the standard dimensions and weight data for NPS 1 Schedule 40 pipe based on ANSI / ASME B36.10, including outside diameter, inside diameter, wall thickness, and weight per meter.
This size is widely used in industrial piping systems, utility services, water lines, and fabrication projects where accurate dimensional data is important for layout, support design, material takeoff, and installation planning.
1 Inch Schedule 40 Pipe Dimensions
- Nominal Pipe Size (NPS): 1 inch
- Diameter Nominal (DN): DN25
- Pipe Schedule: Schedule 40
- Outside Diameter (OD): 33.4 mm
- Wall Thickness: 3.38 mm
- Inside Diameter (ID): 26.64 mm
- Pipe Weight: 2.5 kg/m
- Pipe Weight Including Water: 3.05 kg/m
- Reference Standard: ANSI / ASME B36.10
Schedule 40 Pipe 1 Inch (DN25) Data Table
| NPS | DN | OD (mm) | Wall Thickness (mm) | ID (mm) | Weight (kg/m) |
|---|---|---|---|---|---|
| 1 inch | DN25 | 33.4 | 3.38 | 26.64 | 2.5 |
What Is 1 Inch Schedule 40 Pipe Used For?
1 inch Schedule 40 pipe is commonly used in industrial and utility piping systems where a standardized steel pipe size is required. Engineers, designers, and fabricators often use this size in water distribution systems, utility piping, compressed air lines, process piping systems, mechanical piping layouts, and fabrication work.
Because this is a practical and widely used pipe size, accurate dimensions and weight data are important for support design, installation work, material estimation, and field coordination.
Why These Dimensions Matter in Engineering
In piping and mechanical design, standard pipe dimensions are important for more than simple identification. The outside diameter is used for supports, clamps, insulation sizing, and equipment connection layouts. The inside diameter affects internal flow area and hydraulic calculations. The wall thickness is important for fabrication, welding preparation, and pipe strength, while the pipe weight per meter is essential for support load calculations and installation planning.
Using the correct DN25 Schedule 40 pipe dimensions helps reduce drafting errors, procurement mistakes, and field fit-up problems during construction and fabrication work.
1 Inch DN25 Schedule 40 Pipe for CAD and Drafting Work
For CAD, BIM, and piping drafting work, this size is commonly listed as NPS 1 or DN25. The standard OD of 33.4 mm is especially useful for routing clearance, support detailing, and nozzle or equipment connection references in both 2D drawings and 3D models.
This page can be used as a quick reference for 1 inch Schedule 40 pipe dimensions, DN25 pipe dimensions, and Schedule 40 steel pipe weight per meter during design, drafting, and estimation work.
Frequently Asked Questions
What is the outside diameter of 1 inch Schedule 40 pipe?
The outside diameter of 1 inch Schedule 40 pipe is 33.4 mm.
What is the wall thickness of DN25 Schedule 40 pipe?
The wall thickness is 3.38 mm.
What is the inside diameter of Schedule 40 pipe 1 inch?
The inside diameter is 26.64 mm.
How much does 1 inch Schedule 40 pipe weigh?
The pipe weight is 2.5 kg/m. The weight including water is 3.05 kg/m.
Which standard covers these dimensions?
These dimensions are based on ANSI / ASME B36.10.
Conclusion
Schedule 40 pipe 1 inch (DN25) is an important reference size for industrial piping, drafting, fabrication, and engineering calculations. With an OD of 33.4 mm, ID of 26.64 mm, wall thickness of 3.38 mm, and weight of 2.5 kg/m, it is a useful standard pipe size for engineers, designers, and estimators working with steel piping systems.
For more pipe schedule data, compare this size with nearby standard sizes such as 3/4 inch and 1 1/4 inch Schedule 40 pipe pages.
How to Use This Pipe Reference
Interpret the dimensional terms correctly
The outside diameter is the key envelope dimension for routing clearances, clamps, supports, insulation space, and connection coordination. The inside diameter is used when assessing the available flow passage. The wall thickness supports fabrication and modeling decisions, while the listed mass per meter helps with material estimation and support-load calculations.
Apply the data consistently in CAD and takeoffs
For drawings and three-dimensional models, keep the nominal designation, outside diameter, and wall thickness associated with the same pipe entry. This helps prevent a nominal-size label from being confused with a modeled diameter. The downloadable DWG can support drafting workflows, but users should still check units, layer conventions, connection points, and project-specific modeling requirements before issuing a drawing.
Do not treat schedule alone as a complete design specification
A schedule identifies dimensional wall information for a standardized pipe size, but it does not by itself establish material grade, allowable pressure, temperature limits, corrosion allowance, joining method, or code compliance. Confirm those requirements against the project piping specification and the applicable engineering design basis before procurement or fabrication.
Related Pipe Dimension References
For broader comparison work, pair this reference with the site’s pipe schedule dimensions, NPS-to-DN conversion, pipe weight, and flange and fitting dimension resources. Nearby Schedule 40 size pages are useful when checking line-size transitions, reducer selections, routing clearances, and material takeoffs.
Additional Practical Questions
Is DN25 the measured outside diameter of the pipe?
No. DN25 is a nominal metric designation used to identify the pipe size. The measured dimensions for this reference are the listed outside diameter, inside diameter, and wall thickness.
Can the listed weight including water be used for every support calculation?
It can serve as a reference for the stated condition, but a final support or structural check should account for the complete supported load, including the pipe, contents, fittings, valves, insulation, attachments, and applicable project load cases.
Does Schedule 40 alone determine the allowable operating pressure?
No. Pressure capability depends on factors such as material specification, temperature, manufacturing requirements, joining details, corrosion allowance, and the governing design code. Verify those items before using the pipe in a pressure design.
Why should the nominal size and actual dimensions both appear on a drawing?
The nominal designation supports identification and procurement, while the actual dimensional data supports clearance, support, fabrication, and connection coordination. Showing or referencing both reduces ambiguity during design and field installation.