This reference provides the listed dimensions and weight for 18 inch Schedule 80S stainless steel pipe, also identified as NPS 18 and DN450. Use the table for a quick dimensional check, then review the guidance below when coordinating pipe with fittings, flanges, supports, drawings, and procurement documents.
For broader project work, this page can be read alongside PipeSTD references covering pipe schedules, stainless steel pipe dimensions, pipe fittings, flanges, and piping terminology. Those related references help connect the nominal size shown here with the components and documentation used in a complete piping system.
Schedule 80S Pipe 18 Inch (DN450) is a stainless steel pipe size commonly used in industrial piping systems where corrosion resistance, dimensional consistency, and dependable wall thickness are important. Based on the current page data under ANSI/ASME B36.19, this pipe size has an outside diameter of 457 mm, an inside diameter of 431.6 mm, a wall thickness of 12.7 mm, and a pipe weight of 138.11 kg/m.
18 Inch Schedule 80S Pipe Dimensions
The following values are listed for NPS 18 Schedule 80S pipe, which corresponds to DN450 in metric designation.
- Pipe Size: NPS 18 Inch
- DN Size: DN450
- Outside Diameter (OD): 457 mm
- Inside Diameter (ID): 431.6 mm
- Wall Thickness: 12.7 mm
- Pipe Weight: 138.11 kg/m
- Pipe Weight Including Water: 146.22 kg/m
- Reference Standard: ANSI/ASME B36.19
Schedule 80S Pipe 18 Inch (DN450) Data Table
| Pipe Schedule | NPS | DN | OD (mm) | ID (mm) | Wall Thickness (mm) | Weight (kg/m) |
|---|---|---|---|---|---|---|
| 80S | 18 Inch | 450 | 457 | 431.6 | 12.7 | 138.11 |
What Is Schedule 80S Pipe?
Schedule 80S is a stainless steel pipe schedule designation commonly used under ASME B36.19. In piping design and fabrication, the schedule identifies the wall thickness series for a given nominal pipe size. This helps engineers, buyers, and fabricators confirm dimensional compatibility, estimate pipe weight, and coordinate with fittings, flanges, and supports.
Common Uses of 18 Inch Schedule 80S Pipe
18 inch Schedule 80S pipe is commonly used in stainless steel piping systems that require good corrosion resistance, dependable wall thickness, and substantial flow capacity. This size is often selected for industrial projects where standard dimensions are needed for design, fabrication, procurement, and installation work.
- Process piping systems in chemical and industrial plants
- Water transmission lines for medium to large flow service
- Cooling water and utility piping in plant facilities
- Marine and offshore piping where stainless steel is preferred
- Food and beverage plants requiring corrosion-resistant piping materials
- Pharmaceutical facilities using stainless steel process lines
- Pump suction and discharge piping for larger piping systems
- Pipeline upgrade and replacement work where standard pipe dimensions are required
In practical engineering work, this pipe size may be checked when reviewing flow area, piping layout, support loading, transport weight, and installation requirements. Final pipe selection should always be verified against project pressure, temperature, fluid type, and material specifications.
Why OD, ID, Thickness, and Weight Matter
Exact OD, ID, wall thickness, and weight values are important for pipe support design, material take-off, transport planning, welding preparation, and installation work. Weight data is also useful for lifting calculations and total piping load estimates, while inside diameter affects flow calculations and system capacity review.
NPS 18 and DN450 Explained
NPS means nominal pipe size in inch units, while DN means diameter nominal in metric units. The current page identifies this pipe as NPS 18 and DN450, which is the standard naming format widely used in piping drawings, isometrics, and procurement specifications.
Conclusion
Schedule 80S Pipe 18 Inch (DN450) is listed on the current page with 457 mm OD, 431.6 mm ID, 12.7 mm wall thickness, and 138.11 kg/m weight. It is a useful stainless steel pipe reference for piping engineers, designers, and buyers who need standard dimensional and weight data for project planning and material selection.
How to Use This Pipe Reference
Start with the nominal designation: NPS 18 is the inch-based pipe size, while DN450 is the corresponding metric designation shown on this page. The nominal designation is used for communication and coordination; the actual outside and inside dimensions are the values to use when checking layout clearances, connections, flow-area calculations, and fabrication details.
The outside diameter is especially important for connection alignment, clamp or support arrangement, insulation coordination, and drawing details. The inside diameter is relevant to internal flow space and system review. The listed wall thickness identifies the dimensional series for this schedule, while the listed pipe weight supports material takeoffs, handling reviews, support-load estimates, and transport planning.
Schedule, Material, and Component Coordination
Schedule 80S describes a stainless steel wall-thickness series; it is not, by itself, a complete material specification or a pressure-design approval. Project documents still need to define the applicable material requirements, service conditions, joining method, inspection requirements, and design criteria. Confirm that connected fittings, flanges, valves, and other components are dimensionally and materially compatible before procurement or fabrication.
When preparing an isometric, bill of materials, or CAD model, keep the nominal designation and the actual dimensions together. This reduces the risk of confusing NPS and DN labels with measured OD, ID, or wall thickness. The downloadable DWG can also support drafting workflows, but users should review the drawing content against the current project specification and the authoritative table on this page.
Checks Before Using the Data in a Project
- Confirm that the required pipe material and product specification match the project documents.
- Check the listed dimensions against the connected fittings, flanges, valves, and fabrication details.
- Use the listed pipe weight when developing preliminary material and support-load information, then include applicable contents, insulation, attachments, and design allowances separately.
- Verify pressure, temperature, fluid, corrosion, welding, and code requirements with the responsible engineer.
- Review the DWG and any copied table values against the current page data before issuing drawings or purchase documents.
These checks make the page useful as a dimensional reference without treating a schedule designation alone as a complete engineering design basis.
Frequently Asked Questions
What does 18 inch Schedule 80S pipe mean?
It identifies a stainless steel pipe with an NPS 18 nominal size and a Schedule 80S wall-thickness designation. The page also identifies the metric designation as DN450.
What are the listed OD, ID, and wall thickness?
The current page lists an outside diameter of 457 mm, an inside diameter of 431.6 mm, and a wall thickness of 12.7 mm. Use the table as the local dimensional source for this reference.
What is the listed weight of this pipe?
The listed pipe weight is 138.11 kg/m. The page also gives a pipe weight including water of 146.22 kg/m. These values can support preliminary loading and material planning, but project-specific load combinations and contents should be reviewed separately.
Is Schedule 80S a stainless steel grade?
No. Schedule 80S is a dimensional wall-thickness designation used for stainless steel pipe. It does not identify the complete alloy grade, product specification, or service qualification. Those requirements must come from the project and procurement documents.
Can NPS 18 and DN450 be used as interchangeable labels?
They are the two nominal designations shown for this pipe size. For detailed design and fabrication, do not rely on the labels alone; also check the listed OD, ID, wall thickness, component compatibility, and applicable project requirements.
What should be checked before selecting this pipe for service?
Confirm the material specification, pressure and temperature requirements, fluid and corrosion conditions, connection components, support arrangement, fabrication requirements, and governing project criteria. Final selection requires engineering verification.