This reference page is intended for engineers, designers, fabricators, estimators, and CAD users checking 12 inch Schedule 140 pipe dimensions. Use the table to distinguish nominal size from the pipe’s actual outside diameter, wall thickness, and inside diameter before preparing layouts, material takeoffs, or support calculations.
For related work, compare this entry with the site’s pipe schedule chart, NPS to DN reference, and steel pipe weight resources. Those pages provide useful context when checking adjacent pipe sizes or comparing wall-thickness series.
Schedule 140 pipe 12 inch (DN300) is a heavy-wall steel pipe size commonly used in piping design, fabrication, drafting, and engineering estimation work. This page provides the standard dimensions, wall thickness, inside diameter, and weight per meter for NPS 12 Schedule 140 pipe based on ASME B36.10.
12 Inch Schedule 140 Pipe Dimensions
- Nominal Pipe Size (NPS): 12 inch
- Diameter Nominal (DN): DN300
- Outside Diameter (OD): 323.9 mm
- Wall Thickness: 28.58 mm
- Inside Diameter (ID): 266.64 mm
- Pipe Weight: 208.08 kg/m
- Pipe Weight Filled With Water: 263.89 kg/m
- Reference Standard: ASME B36.10
- Pipe Type: Steel Pipe
Schedule 140 Pipe 12 Inch Data Table
| Pipe Size | DN | OD (mm) | Wall Thickness (mm) | ID (mm) | Weight (kg/m) |
|---|---|---|---|---|---|
| 12 inch | 300 | 323.9 | 28.58 | 266.64 | 208.08 |
What Does Schedule 140 Mean?
Schedule 140 refers to a very heavy wall thickness series used for steel pipe under ASME B36.10. For the same nominal pipe size, the outside diameter remains fixed while the wall thickness increases according to the schedule. A thicker wall reduces the inside diameter and significantly increases pipe weight.
Typical Uses of 12 Inch Schedule 140 Pipe
NPS 12 Schedule 140 pipe is commonly referenced for heavy-duty industrial piping systems where very high wall thickness is required. It may be used in process piping, plant utility systems, structural loading checks, fabrication work, and engineering applications where pipe strength and wall thickness are more critical than maximum flow area.
Why Pipe Weight Matters
Pipe weight per meter is essential for transport planning, crane lifting studies, support design, structural loading, fabrication estimates, and installation planning. For a 12 inch Schedule 140 pipe, the heavy wall thickness results in much higher installed weight than lighter schedules, so accurate weight data is important for engineering and construction work.
12 Inch Schedule 140 Pipe Calculation Notes
The listed weight is based on standard steel pipe dimensions using the outside diameter and wall thickness of the pipe. Actual product weight may vary slightly depending on manufacturing tolerance, material specification, and supplier standard.
Frequently Asked Questions
What is the outside diameter of 12 inch Schedule 140 pipe?
The outside diameter is 323.9 mm.
What is the wall thickness of DN300 Schedule 140 pipe?
The wall thickness is 28.58 mm.
What is the inside diameter of NPS 12 Schedule 140 pipe?
The inside diameter is 266.64 mm.
How much does 12 inch Schedule 140 pipe weigh?
The approximate weight is 208.08 kg/m.
Which standard covers this pipe size?
This dimension data is based on ASME B36.10 for steel pipe.
Conclusion
Schedule 140 pipe 12 inch (DN300) has an outside diameter of 323.9 mm, wall thickness of 28.58 mm, inside diameter of 266.64 mm, and a weight of 208.08 kg/m. It is a useful reference for piping design, fabrication, estimating, and heavy-duty industrial engineering work.
How to Use This Pipe Reference
NPS 12 and DN300 identify the same nominal pipe size in customary and metric terminology. They are size designations rather than direct measurements of the pipe bore. The outside diameter is controlled by the nominal size, while the schedule identifies the wall-thickness series used for the pipe.
When reviewing a drawing or material list, check the outside diameter for fit-up, supports, clamps, and connection geometry. Check the inside diameter when reviewing flow-path geometry, lining space, or internal clearances. The listed mass per meter is useful for estimating handling loads and installed dead load, but final support and structural decisions require the complete project specification and engineering verification.
Related Design and Drafting References
- Pipe schedule comparison: compare Schedule 140 with other wall-thickness series for the same nominal size.
- Pipe weight calculator: use pipe length and the listed mass-per-meter value for preliminary material estimates.
- Flange dimensions: check the matching connection reference separately when developing piping layouts.
- Pipe fittings and terminology: clarify how elbows, tees, reducers, and other components are identified in drawings and bills of materials.
- CAD and DWG resources: download the supplied drawing when a dimensioned drafting reference is needed.
The accompanying DWG file can support drafting and coordination workflows. Confirm units, drawing scale, tolerances, material grade, end preparation, and project requirements before using any CAD geometry for fabrication or procurement.
Additional Questions About This Reference
Are NPS 12 and DN300 interchangeable labels?
They are the customary and metric nominal designations used for this pipe size. Always verify the actual dimensions in the table rather than treating either label as the measured bore.
Should the listed pipe weight be used as a final structural load?
No. The listed value is a reference mass per meter. Final support, lifting, seismic, and structural checks should account for the project specification, connected components, contents, insulation, corrosion allowance, and applicable engineering requirements.
Does the schedule designation identify the pipe material grade?
No. Schedule 140 describes the wall-thickness series. Material grade, manufacturing requirements, testing, end preparation, and other procurement details must be confirmed separately.
Can the DWG file replace a fabrication drawing?
No. The DWG is a reference resource. A fabrication drawing should be reviewed and approved against the applicable project documents, dimensions, tolerances, connections, and material requirements.