Use this page as a practical reference for 12 inch Schedule 5 pipe dimensions and the equivalent DN300 designation. The page brings together dimensional, weight, terminology, and drafting information so engineers, designers, fabricators, and procurement teams can find the relevant pipe data in one place.
When using the table for a project, distinguish nominal size from measured geometry. NPS and DN identify the nominal pipe size, while outside diameter, inside diameter, wall thickness, and mass per unit length support different layout, fabrication, and coordination tasks. Always confirm the project material specification, manufacturing requirements, joining details, and applicable design rules before issuing the data for construction or procurement.
Schedule 5 Pipe 12 Inch (DN300) is a large steel pipe size commonly used in industrial piping systems that require high flow capacity with a relatively light wall thickness. This pipe size is often used in utility piping, water transfer systems, low-pressure industrial service, and general steel pipe fabrication work.
This dimension data is based on ANSI/ASME B36.10, which is the standard commonly used for carbon steel pipe dimensions.
12 Inch Schedule 5 Pipe Dimensions
- Pipe Schedule: 5
- Nominal Pipe Size: 12 Inch
- DN Size: DN300
- Outside Diameter (OD): 323.9 mm
- Inside Diameter (ID): 315.88 mm
- Wall Thickness: 3.96 mm
- Pipe Weight: 31.24 kg/m
- Pipe Weight Including Water: 109.56 kg/m
- Standard: ANSI/ASME B36.10
Schedule 5 Pipe 12 Inch Dimension Table
| Pipe Schedule | NPS (Inch) | DN (mm) | OD (mm) | ID (mm) | Wall Thickness (mm) | Weight (kg/m) |
|---|---|---|---|---|---|---|
| 5 | 12 | 300 | 323.9 | 315.88 | 3.96 | 31.24 |
What Is 12 Inch Schedule 5 Pipe?
A 12 inch Schedule 5 pipe is a steel pipe with a nominal size of 12 inches and a relatively thin wall thickness compared with heavier schedules. For this size, the outside diameter is fixed at 323.9 mm, while the inside diameter is 315.88 mm based on a wall thickness of 3.96 mm.
Schedule 5 pipe is often selected when a project needs large flow capacity, reduced pipe weight, and easier handling compared with thicker wall pipes. It is commonly referenced in steel piping design, drafting, fabrication, and material takeoff work.
Where Is Schedule 5 Pipe 12 Inch Used?
This pipe size is commonly used in applications that need large flow capacity with relatively light wall thickness. Typical uses include:
- Water transfer and distribution systems
- Utility and low-pressure industrial piping
- Large process and service lines
- Pipe spool fabrication and layout work
- General steel piping projects
Why Pipe Dimensions Matter
Accurate 12 inch Schedule 5 pipe dimensions are important for piping layout, fabrication, transport planning, support design, and installation work. Engineers and designers often check OD, ID, wall thickness, and weight before selecting supports, fittings, welding details, and handling methods.
The outside diameter is important for matching supports, clamps, and pipe accessories. The inside diameter helps estimate internal flow area and system capacity. The wall thickness affects mechanical strength and specification compliance, while the pipe weight per meter is useful for lifting plans, transport, and structural loading calculations.
12 Inch Schedule 5 Pipe Weight Information
The nominal weight of this pipe size is 31.24 kg/m. When filled with water, the combined weight becomes approximately 109.56 kg/m. This information is useful for pipe support design, structural coordination, and lifting preparation in large piping systems.
Difference Between NPS 12 and DN300
NPS 12 is the inch-based nominal pipe size, while DN300 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 size 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 12 inch Schedule 5 pipe dimensions, DN300 Schedule 5 pipe dimensions, 12 inch pipe weight per meter, DN300 pipe dimensions, or DN300 sch 5 pipe dimensions.
Conclusion
Schedule 5 Pipe 12 Inch (DN300) has an outside diameter of 323.9 mm, an inside diameter of 315.88 mm, a wall thickness of 3.96 mm, and a weight of 31.24 kg/m. It is a useful 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 12 inch Schedule 5 pipe dimensions and DN300 pipe dimensions in one place.
How to Use This Pipe Reference
The dimensional values on this page are most useful when coordinated with the rest of the piping system. The outside diameter can be checked against supports, clamps, sleeves, and connection components. The inside diameter can support preliminary flow-area discussions, while wall thickness and listed weight help with fabrication coordination, handling, and support-load reviews.
Schedule designation should be treated as a dimensional reference, not as a complete design qualification. Pressure, temperature, corrosion allowance, material grade, manufacturing method, joining method, and local project requirements may all affect whether a pipe is appropriate for service. A qualified engineer should verify the complete piping specification before selection.
Related Pipe and Piping References
This page works well alongside related references for pipe schedule charts, NPS and DN conversion, pipe outside diameter, and pipe wall thickness. Those resources help readers compare this nominal size with other schedules and sizes without confusing a change in schedule with a change in outside diameter.
For connection and layout work, add internal references to pipe fittings, flange dimensions, pipe supports, and piping isometric drawing terminology. The downloadable DWG is especially useful for users preparing CAD layouts, spool drawings, or preliminary coordination models; the drawing should still be checked against the project’s approved dimensions and fabrication requirements.
Design and Drafting Checks
- Confirm whether the drawing or specification uses NPS, DN, or both designations.
- Use the listed outside diameter when coordinating supports, clamps, sleeves, and clearance zones.
- Check the inside diameter when discussing flow area or internal equipment connections.
- Use the listed pipe weight for preliminary handling and support coordination, then verify the complete installed-load case.
- Confirm whether lining, coating, insulation, fittings, valves, contents, and other attachments must be included in project load calculations.
- Review the applicable material and piping specification before procurement or fabrication.
Frequently Asked Questions
What is the nominal size of Schedule 5 pipe covered here?
The reference covers NPS 12 pipe, also identified as DN300. NPS and DN are nominal designations; they should not be read as direct substitutes for every measured pipe dimension.
What information is included on this page?
The page includes the pipe schedule, nominal size, DN designation, outside diameter, inside diameter, wall thickness, pipe weight, water-filled weight, and a downloadable CAD reference.
Is Schedule 5 a pressure rating?
No. A schedule identifies a pipe wall-dimension category. Suitability for a particular pressure or temperature service requires review of the material, design conditions, applicable code, corrosion requirements, and project specification.
Why are both NPS 12 and DN300 shown?
NPS 12 is the inch-based nominal designation, while DN300 is the metric designation used in many international drawings and specifications. Showing both helps prevent confusion when documents use different piping conventions.
Can the listed pipe weight be used as the final support load?
It can support preliminary coordination, but the final support and structural review should account for the complete installed condition. Depending on the application, that may include contents, insulation, coatings, valves, fittings, dynamic effects, and support spacing.
What other references should be checked before using the DWG?
Coordinate the DWG with the project’s pipe specification, fitting and flange references, connection details, support standards, and approved design documents. CAD geometry is a drafting aid and does not replace engineering verification.