This reference page brings together the dimensional and weight information used to identify 1 inch Schedule 40S stainless steel pipe, also designated as DN25. Use the data below when checking piping layouts, fabrication drawings, material takeoffs, supports, and related component selections.
For efficient project work, compare this reference with the applicable pipe schedule, fittings, flanges, and piping terminology resources on PipeSTD. The nominal size identifies the pipe designation; the listed outside diameter, inside diameter, and wall thickness are the values to use when coordinating physical interfaces and clearances.
Schedule 40S Pipe 1 Inch (DN25) is a stainless steel pipe size commonly used in industrial piping systems that require corrosion resistance, dependable wall thickness, and reliable flow capacity. This pipe size is often used in process plants, utility systems, water treatment projects, and stainless steel fabrication work.
This dimension data is based on ANSI/ASME B36.19, which is the standard commonly used for stainless steel pipe dimensions.
1 Inch Schedule 40S Pipe Dimensions
- Pipe Schedule: 40S
- Nominal Pipe Size: 1 Inch
- DN Size: DN25
- Outside Diameter (OD): 33.4 mm
- Inside Diameter (ID): 26.64 mm
- Wall Thickness: 3.38 mm
- Pipe Weight: 2.5 kg/m
- Pipe Weight Including Water: 3.05 kg/m
- Standard: ANSI/ASME B36.19
Schedule 40S Pipe 1 Inch Dimension Table
| Pipe Schedule | NPS (Inch) | DN (mm) | OD (mm) | ID (mm) | Wall Thickness (mm) | Weight (kg/m) |
|---|---|---|---|---|---|---|
| 40S | 1 | 25 | 33.4 | 26.64 | 3.38 | 2.5 |
What Is 1 Inch Schedule 40S Pipe?
A 1 inch Schedule 40S pipe is a stainless steel pipe with a nominal size of 1 inch and a wall thickness defined by the 40S schedule. For this size, the outside diameter is fixed at 33.4 mm, while the inside diameter is 26.64 mm based on a wall thickness of 3.38 mm.
The letter S in 40S is commonly used for stainless steel pipe dimensions under ASME B36.19. This designation is widely used by engineers, fabricators, and procurement teams when selecting stainless steel piping for industrial service.
Where Is Schedule 40S Pipe 1 Inch Used?
This pipe size is commonly used in systems that need both good flow capacity and the corrosion resistance of stainless steel. Typical applications include:
- Process piping in industrial plants
- Water treatment and utility systems
- Food and beverage piping lines
- Chemical service piping
- Stainless steel branch and service lines
Why Pipe Dimensions Matter
Accurate 1 inch Schedule 40S pipe dimensions are important for piping layout, fabrication, support design, transport planning, and material takeoff. Engineers and designers often check OD, ID, wall thickness, and weight before selecting flanges, fittings, supports, and installation methods.
The outside diameter is important for matching clamps, flanges, and pipe supports. The inside diameter helps estimate flow area and system capacity. The wall thickness is important for specification compliance and mechanical strength, while the pipe weight per meter is useful for structural loading, support design, and handling calculations.
1 Inch Schedule 40S Pipe Weight Information
The nominal weight of this pipe size is 2.5 kg/m. When filled with water, the combined weight becomes approximately 3.05 kg/m. This information is useful for lifting plans, support design, and pipe rack load calculations in industrial projects.
Difference Between NPS 1 and DN25
NPS 1 is the inch-based nominal pipe size, while DN25 is the metric designation used in international drawings and specifications. Both terms refer to the same nominal pipe size, and users may search by either inch or DN format depending on project standards.
Common Search Terms for This Pipe Size
Users may also search for this pipe using related keywords such as 1 inch Schedule 40S pipe dimensions, DN25 Schedule 40S pipe dimensions, 1 inch stainless steel pipe weight, DN25 pipe dimensions, or DN25 sch 40s pipe dimensions.
Conclusion
Schedule 40S Pipe 1 Inch (DN25) has an outside diameter of 33.4 mm, an inside diameter of 26.64 mm, a wall thickness of 3.38 mm, and a weight of 2.5 kg/m. It is a useful stainless steel pipe reference size for design, drafting, fabrication, and procurement work.
This page provides a quick reference for engineers, drafters, fabricators, and buyers who need reliable 1 inch Schedule 40S pipe dimensions and DN25 pipe dimensions in one place.
How to Read This Schedule 40S Pipe Reference
The table separates the pipe’s nominal designation from its physical dimensions. NPS 1 and DN25 are naming systems for the same nominal pipe size, while the outside diameter is the key reference for many layout and connection checks. The inside diameter is useful when considering the available passage through the pipe.
Schedule, wall thickness, and inside diameter
In this reference, 40S identifies the stainless steel schedule designation associated with the listed wall thickness. Because inside diameter is related to the outside diameter and wall thickness, a change in schedule or pipe specification should not be assumed to have the same internal opening. Always use the dimension table for the exact pipe designation being documented.
Using the dimensions in drawings
Use the outside diameter when checking pipe supports, clamps, sleeves, clearances, and connection geometry. Use the inside diameter when reviewing flow passage or checking transitions between connected components. For fabrication and drafting, keep the nominal designation and the dimensional values together so that a drawing reader does not mistake a nominal size for a measured diameter.
Using the listed weight
The dry pipe weight supports material takeoffs, handling planning, and preliminary support-load reviews. The water-filled figure is a reference for a pipe containing water; actual installed loads may also depend on the fluid, insulation, valves, fittings, supports, and project-specific design requirements. Final structural and piping design checks should be completed against the governing project criteria.
Related PipeSTD references
This page works well alongside PipeSTD references for stainless steel pipe dimensions, pipe schedules, pipe fittings, flange dimensions, and DWG pipe resources. Linking those topics from this page can help readers move from a dimensional lookup to connection selection, drafting, and fabrication coordination.
Frequently Asked Questions
What does 1 inch Schedule 40S pipe mean?
It identifies a stainless steel pipe with the nominal size NPS 1 and the 40S schedule designation. The corresponding metric nominal designation is DN25.
Are NPS 1 and DN25 the same pipe size?
They are different designation systems for the same nominal pipe size. The physical dimensions should still be taken from the applicable schedule reference rather than inferred from the nominal name alone.
Which dimension is most important for a pipe support?
The outside diameter is generally the starting dimension for checking support, clamp, sleeve, and clearance compatibility. The support arrangement and project design requirements must also be reviewed.
Why is the inside diameter included?
The inside diameter describes the available internal passage and can assist with flow-area reviews, connected-component checks, and drafting coordination.
Can the listed water-filled weight be used as the final design load?
It is a useful reference value for a water-filled pipe, but it should not automatically be treated as the complete installed load. Review the actual contents and all attached or supported components before finalizing structural or support calculations.
Is a DWG available for this pipe size?
The page includes a DWG download for Schedule 40S Pipe 1 Inch (DN25). Confirm that the drawing designation matches the project specification before using it for fabrication or issued-for-construction documentation.