Need a quick reference for Schedule 20 Pipe 12 Inch (DN300)? This page brings together the dimensional and weight data most often needed for piping layouts, CAD drawings, material takeoffs, support reviews, and fabrication coordination.
Use the table and summary below to distinguish the nominal size from the actual outside diameter, review the Schedule 20 wall thickness, and select the appropriate weight basis for planning work. The listed values are local reference data for NPS 12 steel pipe and should be checked against the project specification before procurement or final design.
Schedule 20 pipe 12 inch (DN300) is a standard steel pipe size commonly used in piping design, drafting, fabrication, estimation, and industrial layout work. This page provides the standard dimensions, wall thickness, inside diameter, and weight per meter for NPS 12 Schedule 20 pipe based on ASME B36.10.
For engineers, designers, estimators, and CAD users, quick access to accurate pipe data helps improve piping layout, support planning, weight checks, material takeoff, and fabrication coordination during project development.
12 Inch Schedule 20 Pipe Dimensions
- Nominal Pipe Size (NPS): 12 inch
- Diameter Nominal (DN): DN300
- Outside Diameter (OD): 323.9 mm
- Wall Thickness: 6.35 mm
- Inside Diameter (ID): 311.1 mm
- Pipe Weight: 49.71 kg/m
- Pipe Weight Including Water: 125.68 kg/m
- Standard: ASME B36.10
Schedule 20 Pipe 12 Inch Data Table
| NPS | DN | Outside Diameter (OD) | Wall Thickness | Inside Diameter (ID) | Weight |
|---|---|---|---|---|---|
| 12 inch | DN300 | 323.9 mm | 6.35 mm | 311.1 mm | 49.71 kg/m |
Understanding 12 Inch Schedule 20 Pipe
12 inch Schedule 20 pipe is a standard steel pipe size used as a reference in industrial piping layouts, utility lines, water systems, process design studies, and CAD drafting. With an outside diameter of 323.9 mm and a wall thickness of 6.35 mm, this pipe size is useful where a practical flow path is needed while keeping the wall lighter than heavier schedules.
What Does Schedule 20 Mean?
Schedule 20 refers to the wall thickness series of the pipe. For NPS 12, Schedule 20 gives a wall thickness of 6.35 mm. The schedule affects the inside diameter, pipe weight, fabrication requirements, and dimensional coordination with fittings, supports, and layout clearances.
Why These Pipe Dimensions Matter
Accurate pipe dimension data is important for piping layouts, spool drawings, support design, structural load review, and material takeoff. Knowing that this pipe weighs 49.71 kg/m helps with transport estimates, lifting plans, and support loading. If the pipe is filled with water, the total weight increases to 125.68 kg/m, which is also useful for operating load calculations.
Common Uses of DN300 Schedule 20 Pipe
DN300 Schedule 20 pipe may be referenced in industrial utility systems, water transfer lines, plant layout studies, process piping documentation, and engineering design work. It is also commonly used by piping designers, CAD users, estimators, and procurement teams who need fast access to standard steel pipe dimensions.
Difference Between NPS 12 and DN300
NPS 12 is the inch-based nominal pipe size designation, while DN300 is the metric nominal diameter reference. Both refer to the same pipe size category on this page. The actual standard outside diameter for this size is 323.9 mm.
How to Use This Data
You can use this page to quickly check:
- pipe outside diameter for layout and clearance
- inside diameter for flow reference
- wall thickness for schedule comparison
- weight per meter for estimation and transport planning
- water-filled weight for support and structural load review
Quick Reference for Schedule 20 Pipe 12 Inch
- Pipe Size: 12 inch
- DN: DN300
- OD: 323.9 mm
- ID: 311.1 mm
- Wall Thickness: 6.35 mm
- Weight: 49.71 kg/m
- Weight Including Water: 125.68 kg/m
- Reference Standard: ASME B36.10
Related Pipe Size Pages
Conclusion
Schedule 20 Pipe 12 Inch (DN300) is an important steel pipe reference for piping design, drafting, estimation, and fabrication work. With its 323.9 mm outside diameter, 6.35 mm wall thickness, and 49.71 kg/m pipe weight, it provides useful dimensional data for engineers and designers who need fast and accurate pipe information.
Note: NPS = Nominal Pipe Size, DN = Diameter Nominal. Dimensions and weights shown here are based on ASME B36.10 steel pipe data.
How to Read the 12 Inch DN300 Pipe Data
NPS 12 and DN300 identify the same nominal pipe size in inch-based and metric terminology. These designations are not the same as the measured outside diameter. For layout and clearance checks, use the listed OD; for a basic bore or flow reference, use the listed ID.
Use outside diameter for layout coordination
The outside diameter is the key dimension when checking pipe-rack spacing, penetration openings, insulation clearance, clamp arrangements, and the relationship between straight pipe and nearby equipment. Fittings, flanges, valves, and supports must also be coordinated with the applicable dimensional references rather than with the nominal size alone.
Use wall thickness and schedule for comparison
Schedule 20 identifies the pipe wall series for this nominal size. Wall thickness affects the resulting inside diameter, mass per unit length, fabrication details, and coordination with connected components. When comparing another schedule, compare all relevant dimensions and weights instead of assuming that the nominal size has changed.
Choose the correct weight basis
The listed pipe weight is useful for material estimates, handling, transportation, and preliminary support-load reviews. The water-filled figure represents a different loading condition and is relevant when reviewing an operating or filled line. Final support and structural checks should also account for the project design basis, contents, insulation, fittings, valves, testing conditions, and other attached loads where applicable.
Important design and procurement check
This reference supports drafting and early engineering work, but it does not by itself establish pressure capability, material grade, corrosion allowance, manufacturing tolerance, or code compliance. Confirm the required material, joining method, pressure class, and project specifications before issuing purchase documents or approving fabrication.
For adjacent size comparisons, see the existing references for Schedule 20 Pipe 10 Inch (DN250) and Schedule 20 Pipe 14 Inch (DN350).
Frequently Asked Questions
What is the outside diameter of 12 inch Schedule 20 pipe?
The listed outside diameter for NPS 12 Schedule 20 pipe is 323.9 mm. Use this value for general layout and clearance coordination.
What is the wall thickness of Schedule 20 pipe in DN300?
The Schedule 20 wall thickness shown for DN300 is 6.35 mm. The applicable schedule identifies the wall series for this nominal pipe size.
What is the inside diameter of 12 inch Schedule 20 pipe?
The listed inside diameter is 311.1 mm. Treat it as the reference internal dimension shown in the source data and confirm project-specific requirements before flow or hydraulic design.
How much does 12 inch Schedule 20 pipe weigh?
The listed pipe weight is 49.71 kg/m. This value is useful for estimating, lifting, transport, and preliminary support-load reviews.
What is the weight of the pipe when filled with water?
The listed pipe weight including water is 125.68 kg/m. Use the filled-line condition when it matches the load case being reviewed, and include other applicable attached loads in the final engineering check.
Are NPS 12 and DN300 the same pipe size?
On this page, NPS 12 and DN300 refer to the same nominal pipe size category. The actual outside diameter is listed separately because nominal designations do not directly state the measured OD.
Which standard is referenced for this pipe data?
The page identifies ASME B36.10 as the reference standard for the listed steel pipe dimensions and weights. Project specifications and procurement documents should still be reviewed for additional requirements.