Use this page as a quick reference when a piping drawing, material takeoff, or fabrication document identifies 1 inch Schedule XXS pipe. The table provides the dimensional data, while the notes below explain how nominal size, outside diameter, inside diameter, wall thickness, and weight relate to practical engineering work.
For additional drafting and design context, pair this reference with the site’s guides on pipe schedules, NPS and DN terminology, pipe fittings, flange dimensions, and piping CAD/DWG resources. Those related topics help connect a straight-pipe dimension check with the fittings, connection details, and drawing information used in a complete piping system.
Schedule XXS Pipe 1 Inch (DN25) is a heavy-wall steel pipe size used in industrial piping systems, plant construction, high-duty utility lines, and fabrication work. This page provides a practical reference for the main dimensions and weight of 1 inch XXS pipe based on ANSI/ASME B36.10.
For piping engineers, designers, estimators, fabrication teams, and site supervisors, accurate pipe size data is important for layout work, material takeoff, support design, transport planning, and installation checks. This guide presents the essential dimensions in a cleaner format that adds more value than a simple size table.
1 Inch Schedule XXS Pipe Dimensions
- Pipe Size: 1 Inch
- Nominal Diameter: DN25
- Pipe Schedule: XXS (Double Extra Strong)
- Outside Diameter (OD): 33.4 mm
- Inside Diameter (ID): 15.22 mm
- Wall Thickness: 9.09 mm
- Pipe Weight: 5.45 kg/m
- Pipe Weight Including Water: 5.63 kg/m
- Reference Standard: ANSI/ASME B36.10
Schedule XXS Pipe 1 Inch Table
| NPS | DN | OD (mm) | ID (mm) | Wall Thickness (mm) | Weight (kg/m) |
|---|---|---|---|---|---|
| 1″ | 25 | 33.4 | 15.22 | 9.09 | 5.45 |
What Does Schedule XXS Mean?
Schedule XXS means Double Extra Strong. It is a heavy-wall pipe designation used for applications that need thicker pipe walls than standard or lighter schedules. A thicker wall affects the inside diameter, pipe weight, fabrication requirements, support loading, and handling during installation.
For a size such as 1 inch DN25 pipe, the jump to XXS creates a much heavier pipe than lighter schedules, so correct dimension and weight data are important for design, lifting, and field work.
Why 1 Inch DN25 XXS Pipe Dimensions Matter
Knowing the exact dimensions of 1 inch Schedule XXS pipe is useful for several engineering and construction tasks:
- Fabrication: OD and wall thickness are needed for cutting, beveling, welding, and fit-up work.
- Support Design: Pipe weight per meter helps engineers check support spacing and structural loads.
- Flow Review: ID is useful for estimating internal flow area and hydraulic performance.
- Transport and Lifting: Heavy-wall pipes require accurate weight data for safer handling and planning.
- Schedule Comparison: Engineers often compare XXS with XS, STD, Sch 80, Sch 160, or other heavy-wall options during design review.
Typical Applications of 1 Inch Schedule XXS Pipe
This pipe size may be used in:
- Heavy-duty industrial piping
- High-pressure process systems
- Power and utility projects
- Plant piping works
- Oil and gas facilities
- Custom steel fabrication and spool projects
Engineering Notes
NPS means Nominal Pipe Size, while DN means Diameter Nominal. Although this pipe is called 1 inch, the actual outside diameter is 33.4 mm according to the standard. The inside diameter changes with the pipe schedule because wall thickness changes from one schedule to another.
That means if you compare the same 1 inch pipe in a different schedule, the OD usually stays the same, while the ID, wall thickness, and pipe weight will change.
Reference
The dimension data on this page is based on ANSI/ASME B36.10, which is widely used for steel pipe dimensions in industrial applications.
How to Use This Pipe Reference
Start with the nominal designation shown on the drawing or specification, then confirm the schedule before selecting dimensions for fabrication or procurement. The nominal designation identifies the standardized pipe size; it is not necessarily the measured outside or inside diameter.
For this XXS entry, the outside diameter is the primary external fit-up dimension. The wall thickness defines how much material lies between the outside and inside surfaces, and the resulting inside diameter is the dimension most relevant to the internal passage. These dimensions should be checked together rather than treated as interchangeable descriptions of pipe size.
Why the Schedule Should Be Confirmed
Schedule designations affect more than the wall alone. A heavier wall can reduce the internal passage, increase the pipe’s mass, and change the practical requirements for cutting, beveling, welding, supports, lifting, and transport. When comparing this entry with another schedule, confirm all listed dimensions and the applicable project specification instead of assuming that a similar nominal size has the same internal geometry.
Using the Weight Data in Project Work
The listed pipe weight can support preliminary material takeoffs, handling plans, support-load reviews, and spool fabrication planning. The water-inclusive value is a separate planning reference for the listed pipe when its internal passage contains water; it should not automatically be treated as the complete operating load for a finished system. Valves, fittings, flanges, insulation, coatings, contents, supports, and project-specific allowances may also affect the final load assessment.
Fabrication and Drawing Checks
- Confirm that the drawing calls for XXS rather than another heavy-wall schedule.
- Use the outside diameter for external fit-up and connection coordination.
- Use the inside diameter when reviewing passage, bore alignment, or hydraulic calculations.
- Check wall thickness before selecting preparation, welding, and inspection details.
- Review the downloadable DWG together with the project drawing standard and revision control process.
Dimension tables are reference data, not a substitute for the governing material specification, purchase documents, design calculations, or qualified engineering review. Confirm material grade, manufacturing requirements, tolerances, corrosion provisions, pressure and temperature conditions, joining details, and applicable project codes before fabrication or installation.
Related Pipe Reference Topics
Readers working with this entry may also need a pipe schedule comparison for alternate wall selections, an NPS-to-DN explanation for drawing coordination, and reference pages for fittings and flanges that connect to the pipe. The available DWG download is useful when the dimensional reference must be carried into drafting or spool-layout work.
Frequently Asked Questions
What does 1 inch Schedule XXS pipe mean?
It identifies a pipe with a nominal one-inch size designation and the XXS, or Double Extra Strong, wall designation. The nominal size should not be read as the actual measured outside diameter.
Does the pipe schedule change the outside diameter?
For the same nominal pipe size, schedule changes primarily affect wall thickness, inside diameter, and weight. Always use the dimension entry for the specific schedule when checking fit-up or clearances.
What is the difference between pipe weight and pipe weight including water?
Pipe weight refers to the listed pipe itself. The water-inclusive figure accounts for the pipe’s internal passage containing water and is useful for certain planning checks, but complete system loads may include additional components and contents.
Why is the inside diameter important?
The inside diameter describes the available internal passage. It is relevant to flow reviews, bore alignment, internal clearance, and comparisons between schedules of the same nominal size.
Can this reference be used for a pressure design?
It can provide dimensional input, but pressure design requires project-specific engineering verification. Material, temperature, corrosion allowance, manufacturing requirements, joining details, code rules, and service conditions must be reviewed separately.
Is a CAD file available for this pipe?
Yes. The page includes a DWG download for Schedule XXS Pipe 1 Inch DN25. Review the file against the current project drawing standards and confirm that the selected revision matches the design documents.