This reference provides the dimensional data, connection details, and CAD resource for a Weld Neck Flange 20 Inch Class 400. Use the listed values when preparing piping layouts, flange details, fabrication drawings, or preliminary coordination documents.
The flange’s tapered hub is welded directly to the pipe, so the final connection depends on more than the flange outside dimensions. Pipe schedule, bore, gasket selection, bolt compatibility, material specification, and the applicable pressure-temperature rating should all be checked against the project requirements.
Weld Neck Flange 20″ Class 400
Weld Neck Flange 20″ Class 400 is widely used in piping systems that require strong, leak-resistant flange connections. It features a long tapered hub that provides excellent stress distribution and is commonly applied in process piping, utility lines, and industrial systems where welding strength and reliability are important.
This dimension data is based on ANSI / ASME B16.5-2020.
Weld Neck Flange 20″ Class 400 Dimensions
- Reference Standard: ANSI / ASME B16.5
- Nominal Pipe Size (NPS):20″
- DN Size: DN500
- Outside Diameter:775mm
- Flange Thickness:69.8mm
- Hub Diameter:587mm
- Bore Diameter: varies depending on pipe schedule and pipe wall thickness
- Raised Face Diameter:584.2mm
- Weight: 266kg
- Number of Bolts:24
- Stud Bolt Size: 1 1/2″ UNC (or M39) x 240 Long
- Hole Diameter: 1 3/4″ (41.275mm)
What Is a Weld Neck Flange?
A weld neck flange is a type of pipe flange designed with a long tapered hub that is welded directly to the pipe. This design helps reduce stress concentration at the flange base and provides better strength under pressure, temperature fluctuation, and cyclic loading.
Common Applications
Weld Neck Flange 20″ Class 400 is commonly used for:
- Process piping systems
- Oil and gas lines
- Water and utility piping
- Higher pressure service
- Pressure piping connections
- Industrial fabrication and maintenance work
CAD Drawing Download
This page includes the CAD drawing file for Weld Neck Flange 20″ Class 400, which can be used for drafting, detailing, piping layout coordination, and fabrication reference.
Available Weld Neck Flange Class 400 Sizes
This size is part of the Weld Neck Flange Class 400 series. Check other sizes in the same category to find matching dimension data and CAD files for your project.
Notes
Before fabrication or installation, always confirm the latest project requirements, flange material specification, pipe schedule, bore size, gasket type, bolt length, and applicable pressure-temperature rating.
How to Use This Flange Reference
The source dimensions identify the flange envelope, hub geometry, raised-face diameter, bolt arrangement, stud bolt information, and listed weight. These values are useful for layout and detailing, while the pipe schedule determines the matching bore. A flange may therefore require a schedule-specific dimensional check before fabrication.
Why the Weld Neck Hub Matters
A weld neck flange transfers the connection into the pipe through its tapered hub. This arrangement is intended to provide a gradual transition and reduce local stress concentration compared with a short, abrupt flange connection. The welding procedure, joint preparation, inspection requirements, and qualified fabrication practices remain project-controlled items.
Connection and Drafting Checks
- Confirm the flange face type and raised-face dimensions before selecting or detailing the gasket.
- Match the bore to the pipe schedule and actual pipe wall thickness used in the design.
- Check the stud bolt size, length, number of bolts, and hole diameter against the mating flange and bolting specification.
- Use the listed weight for handling and layout reference, while confirming the final assembly weight if gaskets, bolts, and other components are included.
- Verify the applicable material, pressure-temperature rating, inspection, and installation requirements before release for fabrication.
Related Reference Topics
For broader design context, connect this page to related references covering pipe schedules, flange dimensions, raised-face flanges, stud bolt sizing, gasket selection, and piping CAD blocks. These links help readers move from the flange outline to the pipe, bolting, sealing, and drafting decisions that control a complete connection.
CAD File Use
The downloadable DWG is intended as a drafting and coordination aid. Before using it for fabrication, compare the drawing with the project’s approved dimensions, pipe schedule, material requirements, flange facing, and revision-controlled specifications.
Frequently Asked Questions
What is the bore of this Weld Neck Flange?
The bore varies with the pipe schedule and pipe wall thickness. Confirm the matching pipe specification before finalizing the flange or weld detail.
How many bolts are used?
The source data lists 24 bolts for this Weld Neck Flange 20 Inch Class 400 reference.
What stud bolt information is provided?
The listed stud bolt is 1 1/2" UNC (or M39) x 240 Long. Confirm the required bolting material, thread form, length, and installation requirements for the mating flange and gasket assembly.
Is Class 400 a universal pressure value?
No. A flange class designation must be evaluated with the applicable material and temperature conditions. Use the project pressure-temperature requirements and the governing flange specification for acceptance.
Can the DWG be used directly for fabrication?
The DWG can support drafting, layout coordination, and fabrication reference. It should be checked against the approved project specification and the actual pipe, gasket, bolting, and material requirements before fabrication.