This reference is intended for engineers, drafters, estimators, fabricators, and construction teams who need to identify 3 1/2 inch DN90 Schedule XS pipe during design or field work. The table below provides the dimensional data in both U.S. nominal pipe sizing and metric terminology, making it easier to coordinate piping layouts, material takeoffs, and fabrication documents.
Use the dimensional values as a starting point for checking clearances, connections, supports, and spool details. For related design work, this page can be paired with references on pipe schedules, flange dimensions, pipe fittings, pipe support loads, and CAD/DWG piping resources.
Schedule XS Pipe 3 1/2 Inch (DN90) is a steel pipe size commonly used in industrial piping systems, utility lines, water transmission projects, plant construction, and fabrication work. This page provides a practical reference for the main dimensions and weight of 3 1/2 inch XS pipe based on ANSI/ASME B36.10.
For piping engineers, CAD 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.
3 1/2 Inch Schedule XS Pipe Dimensions
- Pipe Size: 3 1/2 Inch
- Nominal Diameter: DN90
- Pipe Schedule: XS (Extra Strong)
- Outside Diameter (OD): 101.6 mm
- Inside Diameter (ID): 85.44 mm
- Wall Thickness: 8.08 mm
- Pipe Weight: 18.64 kg/m
- Pipe Weight Including Water: 24.37 kg/m
- Reference Standard: ANSI/ASME B36.10
Schedule XS Pipe 3 1/2 Inch Table
| NPS | DN | OD (mm) | ID (mm) | Wall Thickness (mm) | Weight (kg/m) |
|---|---|---|---|---|---|
| 3 1/2″ | 90 | 101.6 | 85.44 | 8.08 | 18.64 |
What Does Schedule XS Mean?
Schedule XS stands for Extra Strong. It is a pipe wall designation used in steel pipe standards. The selected schedule affects the wall thickness, which directly affects the inside diameter, pipe weight, fabrication requirements, and support loading.
For a size such as 3 1/2 inch DN90 pipe, wall thickness remains important because it affects total pipe weight, handling requirements, support loads, and installation planning in real projects.
Why 3 1/2 Inch DN90 Pipe Dimensions Matter
Knowing the exact dimensions of 3 1/2 inch Schedule XS 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: Accurate weight data supports safer handling and planning.
- Schedule Comparison: Engineers often compare XS with STD, Sch 40, Sch 60, or Sch 80 during design review.
Typical Applications of 3 1/2 Inch Schedule XS Pipe
This pipe size may be used in:
- Industrial process piping
- Water transmission systems
- Power and utility projects
- Plant piping works
- Infrastructure construction
- Custom steel fabrication and spool projects
Engineering Notes
NPS means Nominal Pipe Size, while DN means Diameter Nominal. Although this pipe is called 3 1/2 inch, the actual outside diameter is 101.6 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 3 1/2 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 Dimension Reference
The nominal size identifies the pipe designation; it should not be treated as a direct measurement of the outside or inside diameter. For layout and fabrication, the listed outside diameter is especially important for supports, clamps, sleeves, branch connections, and clearance checks. The listed inside diameter is more relevant to flow review and internal passage requirements.
Schedule XS identifies a heavier wall designation than lighter schedule options for the same nominal pipe size. As the wall becomes thicker, the available internal diameter is reduced and the pipe mass increases. These relationships are why schedule selection affects more than the label on a drawing: it can influence welding preparation, handling, support reactions, and the space available for flow.
Practical Checks Before Using the Data
- Confirm that the drawing, purchase description, and material documentation all identify the same nominal size and schedule.
- Use the outside diameter when checking physical fit, supports, clamps, sleeves, and connected components.
- Use the inside diameter when reviewing flow passage, lining requirements, or internal access.
- Use the listed pipe weight for preliminary handling and support-load discussions, then account for the complete assembled system, including contents, fittings, valves, insulation, and other attachments where applicable.
- Check the applicable project specification and fabrication requirements before releasing shop drawings or material orders.
Related PipeSTD References
Readers comparing this entry with another wall designation may also want to review the site’s references for STD pipe, Schedule 40 pipe, Schedule 60 pipe, and Schedule 80 pipe. Dimension pages for pipe flanges and butt-weld fittings can help when developing connection details, while a pipe weight calculator or piping material takeoff guide can support estimating and planning workflows.
Design Caution
Dimensions and tabulated mass do not by themselves establish pressure rating, allowable stress, corrosion allowance, weld qualification, or structural adequacy. Those checks require the applicable project design basis, material requirements, loading conditions, and engineering review.
Frequently Asked Questions
What does 3 1/2 inch DN90 mean?
3 1/2 inch is the nominal pipe size designation used in U.S.-based piping terminology, while DN90 is the corresponding metric nominal designation shown in this reference. Neither designation should be read as the actual measured bore.
What does XS mean in pipe sizing?
XS means Extra Strong. It identifies a heavier wall category, which affects the pipe’s wall thickness, internal diameter, mass, fabrication, and support considerations.
Does changing the schedule change the outside diameter?
For this nominal pipe size, the outside diameter generally remains associated with the size designation, while a different schedule changes the wall thickness, inside diameter, and weight. Always use the applicable schedule table when comparing alternatives.
Can these dimensions be used for pressure design?
The dimensions are useful for identification, layout, fabrication planning, and preliminary coordination. Pressure design also requires project-specific material, temperature, corrosion, joining, code, and loading checks, so the table should not be used as a complete design approval.
Why is the pipe weight important?
Pipe weight supports preliminary planning for transport, lifting, supports, and installation. Final system loading should also consider contents and connected components such as fittings, valves, insulation, and supports.