Use this reference when you need a quick dimensional check for NPS 20 Schedule 120 pipe in a piping layout, fabrication estimate, support review, or CAD workflow. The page separates nominal size terminology from the measured outside diameter, wall thickness, and inside diameter reported in the table below.
For related work, compare this entry with the site’s pipe schedule reference, pipe weight guide, flange dimension references, and pipe fitting terminology. Those resources help connect a straight-pipe dimension check with the components and drafting information used in a complete piping system.
Schedule 120 pipe 20 inch (DN500) 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 20 Schedule 120 pipe based on ASME B36.10.
20 Inch Schedule 120 Pipe Dimensions
- Nominal Pipe Size (NPS): 20 inch
- Diameter Nominal (DN): DN500
- Outside Diameter (OD): 508 mm
- Wall Thickness: 38.1 mm
- Inside Diameter (ID): 431.8 mm
- Pipe Weight: 441.52 kg/m
- Pipe Weight Filled With Water: 587.88 kg/m
- Reference Standard: ASME B36.10
- Pipe Type: Steel Pipe
Schedule 120 Pipe 20 Inch Data Table
| Pipe Size | DN | OD (mm) | Wall Thickness (mm) | ID (mm) | Weight (kg/m) |
|---|---|---|---|---|---|
| 20 inch | 500 | 508 | 38.1 | 431.8 | 441.52 |
What Does Schedule 120 Mean?
Schedule 120 refers to a 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 20 Inch Schedule 120 Pipe
NPS 20 Schedule 120 pipe is commonly referenced for heavy-duty industrial piping systems where 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 20 inch Schedule 120 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.
20 Inch Schedule 120 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 20 inch Schedule 120 pipe?
The outside diameter is 508 mm.
What is the wall thickness of DN500 Schedule 120 pipe?
The wall thickness is 38.1 mm.
What is the inside diameter of NPS 20 Schedule 120 pipe?
The inside diameter is 431.8 mm.
How much does 20 inch Schedule 120 pipe weigh?
The approximate weight is 441.52 kg/m.
Which standard covers this pipe size?
This dimension data is based on ASME B36.10 for steel pipe.
Conclusion
Schedule 120 pipe 20 inch (DN500) has an outside diameter of 508 mm, wall thickness of 38.1 mm, inside diameter of 431.8 mm, and a weight of 441.52 kg/m. It is a useful reference for piping design, fabrication, estimating, and heavy-duty industrial engineering work.
How to Read This Pipe Reference
NPS 20 and DN500 identify the nominal size, not the exact measured bore of the pipe. The outside diameter is associated with the nominal pipe size, while the schedule identifies the wall-thickness series. The inside diameter is therefore the dimension most directly affected when comparing this pipe with a lighter or heavier schedule of the same nominal size.
For a quick dimensional check, the listed inside diameter is consistent with subtracting twice the wall thickness from the outside diameter. In project work, use the authoritative table on this page for the reported values, and confirm the applicable material specification, manufacturing tolerances, corrosion allowance, joining method, and design conditions before issuing calculations or fabrication documents.
Using the Weight Information in Design Work
The mass-per-length value is useful for preliminary support reactions, handling plans, transportation estimates, rack loading reviews, and material takeoffs. The water-filled value provides a separate planning reference for situations where the line contents contribute to lifting or support loads. Neither value replaces a project-specific load calculation that accounts for insulation, valves, fittings, supports, test conditions, and other attached items.
Drafting and CAD Workflow
When preparing a layout or model, use the outside diameter for spatial coordination and the inside diameter for bore-related checks. The downloadable DWG can support drafting workflows, but the drawing should still be checked against the project’s piping class, connection details, tolerances, and document-control requirements before use as a construction deliverable.
Useful companion references include pipe dimensions by schedule, ASME B36.10 steel pipe references, flange dimensions, butt-weld fitting dimensions, and piping support design basics. These are natural internal-link targets for readers moving from a single pipe size to a complete piping design review.
Additional Reference Questions
Is NPS 20 the same as a measured 20-inch outside diameter?
No. NPS is a nominal pipe-size designation. The applicable outside diameter is the standardized value listed for the pipe size, so nominal designation and measured diameter should not be treated as interchangeable terms.
Why does the schedule affect the inside diameter?
For the same nominal size, the outside diameter remains associated with the size while the schedule changes the wall-thickness series. A thicker wall consequently leaves a smaller internal bore.
Can the listed pipe weight be used as the final support load?
It can support preliminary estimating and coordination, but final support and structural checks should include all relevant pipe contents, insulation, fittings, valves, test conditions, and project-specific requirements.
What should be checked before using the DWG file?
Confirm the drawing’s units, layer and document standards, connection requirements, material specification, and compatibility with the project piping class. Treat the downloadable file as a drafting reference and perform the required engineering review before release.