When a compact pipe size has a heavy wall, the nominal size alone is not enough for fabrication, estimating, or layout work. The outside diameter, inside diameter, wall thickness, and mass all affect how the pipe connects to fittings, occupies space, and loads supports.
This reference separates the nominal designation from the measured dimensions for 3/4 inch (DN20) Schedule XXS pipe. Use the table below for quick checking, then review the engineering notes and the downloadable DWG resource when preparing drawings or fabrication documentation. For related design work, this page can be read alongside internal references for pipe schedules, flanges, fittings, and pipe support design.
Schedule XXS Pipe 3/4 Inch (DN20) is a heavy-wall steel pipe size used in industrial piping systems, plant construction, high-duty utility lines, and fabrication work. This page provides a practical reference for the main dimensions and weight of 3/4 inch XXS pipe based on ANSI/ASME B36.10.
For piping engineers, designers, estimators, fabrication teams, and site supervisors, accurate pipe size data is important for layout work, material takeoff, support design, transport planning, and installation checks. This guide presents the essential dimensions in a cleaner format that adds more value than a simple size table.
3/4 Inch Schedule XXS Pipe Dimensions
- Pipe Size: 3/4 Inch
- Nominal Diameter: DN20
- Pipe Schedule: XXS (Double Extra Strong)
- Outside Diameter (OD): 26.7 mm
- Inside Diameter (ID): 11.06 mm
- Wall Thickness: 7.82 mm
- Pipe Weight: 3.64 kg/m
- Pipe Weight Including Water: 3.73 kg/m
- Reference Standard: ANSI/ASME B36.10
Schedule XXS Pipe 3/4 Inch Table
| NPS | DN | OD (mm) | ID (mm) | Wall Thickness (mm) | Weight (kg/m) |
|---|---|---|---|---|---|
| 3/4″ | 20 | 26.7 | 11.06 | 7.82 | 3.64 |
What Does Schedule XXS Mean?
Schedule XXS means Double Extra Strong. It is a heavy-wall pipe designation used for applications that need thicker pipe walls than standard or lighter schedules. A thicker wall affects the inside diameter, pipe weight, fabrication requirements, support loading, and handling during installation.
For a size such as 3/4 inch DN20 pipe, the jump to XXS creates a much heavier pipe than lighter schedules, so correct dimension and weight data are important for design, lifting, and field work.
Why 3/4 Inch DN20 XXS Pipe Dimensions Matter
Knowing the exact dimensions of 3/4 inch Schedule XXS pipe is useful for several engineering and construction tasks:
- Fabrication: OD and wall thickness are needed for cutting, beveling, welding, and fit-up work.
- Support Design: Pipe weight per meter helps engineers check support spacing and structural loads.
- Flow Review: ID is useful for estimating internal flow area and hydraulic performance.
- Transport and Lifting: Heavy-wall pipes require accurate weight data for safer handling and planning.
- Schedule Comparison: Engineers often compare XXS with XS, STD, Sch 80, Sch 160, or other heavy-wall options during design review.
Typical Applications of 3/4 Inch Schedule XXS Pipe
This pipe size may be used in:
- Heavy-duty industrial piping
- High-pressure process systems
- Power and utility projects
- Plant piping works
- Oil and gas facilities
- Custom steel fabrication and spool projects
Engineering Notes
NPS means Nominal Pipe Size, while DN means Diameter Nominal. Although this pipe is called 3/4 inch, the actual outside diameter is 26.7 mm according to the standard. The inside diameter changes with the pipe schedule because wall thickness changes from one schedule to another.
That means if you compare the same 3/4 inch pipe in a different schedule, the OD usually stays the same, while the ID, wall thickness, and pipe weight will change.
Reference
The dimension data on this page is based on ANSI/ASME B36.10, which is widely used for steel pipe dimensions in industrial applications.
How to Read the 3/4 Inch XXS Pipe Data
The nominal pipe size identifies the standard size family; it does not directly state the measured outside or inside diameter. For this pipe, the listed OD is the dimension commonly used when checking clearances, clamps, fittings, and layout geometry. The ID is the internal opening and is the more relevant dimension for flow-area reviews.
Wall thickness describes the material between the outside and inside surfaces. In a heavy-wall designation such as XXS, that wall reduces the internal opening compared with lighter versions of the same nominal size. It also increases the pipe mass, which matters when estimating material quantities, planning lifting, and checking support reactions.
Using the Weight Values Correctly
The table distinguishes pipe weight from pipe weight including water. The first value describes the pipe itself, while the second represents the listed operating-content condition. These values should be kept separate in support, transport, and load calculations so that the selected design case is clear.
Actual project calculations may also require allowances for fittings, valves, insulation, coatings, supports, test fluid, and other attached items. Confirm the applicable material specification, corrosion allowance, design temperature, pressure basis, and governing piping code before using the dimension data for a final design.
Fabrication and CAD Checks
- Use the OD when checking external clearances and connection geometry.
- Use the wall thickness when reviewing bevel preparation, weld fit-up, and cutting details.
- Use the ID when reviewing bore continuity and preliminary hydraulic assumptions.
- Use the listed mass when developing takeoffs, handling plans, and preliminary support loads.
- Verify that the downloaded DWG matches the project units, revision practice, and required fabrication tolerances before issuing it for construction.
Useful related references include NPS and DN terminology, pipe schedule comparisons, steel pipe fittings, flange dimensions, and piping isometric drafting. Linking these topics from this page helps readers move from a single size lookup to a complete piping design workflow.
Design Use and Verification
Schedule XXS describes a dimensional wall designation; it should not be treated by itself as a complete pressure-rating or material qualification. Final selection requires project-specific review of material grade, joining method, temperature, corrosion or erosion conditions, code requirements, and the connected components. The values on this page are best used as a dimensional reference and checked against the project specification before procurement or construction.
Frequently Asked Questions
What is the nominal size of this XXS pipe?
It is identified as 3/4 inch pipe and corresponds to DN20. The nominal designation should not be confused with the measured outside diameter listed in the reference data.
What does XXS mean in pipe sizing?
XXS means Double Extra Strong. It identifies a heavy-wall pipe designation. Compared with lighter designations in the same nominal size, it changes the wall thickness, internal opening, mass, and fabrication considerations.
Why is the inside diameter smaller than expected?
The inside diameter is determined by the outside diameter and wall thickness. Because XXS pipe has a heavy wall, more of the cross-section is occupied by steel, leaving a smaller internal opening.
Which dimension should be used for fittings and layout?
The outside diameter is generally the key dimensional check for external connection geometry, clearances, clamps, and layout. Always confirm the selected fitting or component specification before fabrication.
Can the listed weight be used for support design?
It can provide a preliminary pipe-load input, but a complete support review should also consider contents, insulation, fittings, valves, test conditions, spacing, dynamic effects, and the applicable project design criteria.
Is the Schedule XXS designation alone a pressure rating?
No. Pressure suitability depends on more than wall designation, including material, temperature, corrosion allowance, joining details, component ratings, and the governing design code. Engineering verification is required for an actual service.
What is the DWG file useful for?
The DWG can support drafting, layout coordination, and reference geometry. Check its units, project conventions, and revision status before incorporating it into an issued drawing.