This reference provides the published dimensions, weight, bolt information, and CAD resource for a Weld Neck Flange 5 Inch Class 400. Use it alongside related pipe dimensions, flange terminology, gasket references, and pipe schedule data when developing piping layouts or fabrication details.
The dimensional list below is the controlling local reference for this page. Because a weld neck flange is welded directly to the pipe, the flange bore must be coordinated with the selected pipe schedule and wall thickness before a drawing or fabrication package is released.
Weld Neck Flange 5″ Class 400
Weld Neck Flange 5″ 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 5″ Class 400 Dimensions
- Reference Standard: ANSI / ASME B16.5
- Nominal Pipe Size (NPS):5″
- DN Size: DN125
- Outside Diameter:279mm
- Flange Thickness:38.1mm
- Hub Diameter:178mm
- Bore Diameter: varies depending on pipe schedule and pipe wall thickness
- Raised Face Diameter:185.7mm
- Weight: 20kg
- Number of Bolts:8
- Stud Bolt Size: 7/8″ UNC (or M24) x 145 Long
- Hole Diameter: 1″ (25.4mm)
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 5″ 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 5″ 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 data identifies the nominal pipe size, DN designation, outside diameter, flange thickness, hub diameter, raised face diameter, bolt quantity, stud bolt size, hole diameter, and listed weight. These values support preliminary drafting and component identification, but they should be checked against the project specification and the applicable flange standard before procurement or fabrication.
Important Coordination Checks
- Confirm the bore: The bore is dependent on the pipe schedule and wall thickness. Select the matching bore rather than treating the flange as interchangeable across all pipe wall options.
- Check the bolt set: Coordinate the listed stud bolt size, length, quantity, and hole diameter with the mating flange, gasket arrangement, and project bolting requirements.
- Review the raised face: The raised face affects gasket selection, mating-flange alignment, and the usable sealing area.
- Verify the weld detail: The tapered hub and direct pipe weld require appropriate fabrication detailing, weld procedures, inspection requirements, and alignment control.
- Use the CAD file carefully: The downloadable DWG is useful for layout and detailing reference. Confirm units, drawing scale, orientation, bore selection, and project-specific revisions before incorporating it into production drawings.
Related Piping References
For a complete flange connection review, compare this page with the site references for pipe schedules, flange dimensions, gasket types, stud bolts, pressure-temperature considerations, and mating flange classes. A related Class 400 weld neck flange size can help with comparison, but it should not be used as a substitute for the selected size and bore.
Frequently Asked Questions
What does a weld neck flange do?
A weld neck flange connects to the pipe through a butt weld and uses a tapered hub to provide a gradual transition from the flange to the pipe. This geometry is intended to support stress distribution in demanding piping service, subject to proper design and fabrication.
Is the bore the same for every 5 inch flange?
No. The listed bore varies with the pipe schedule and wall thickness. The selected bore must match the pipe used in the connection and should be confirmed before ordering or welding.
How many bolts are listed for this flange?
The source data lists eight bolts. Confirm the mating flange, gasket, stud length, bolting material, and tightening requirements as part of the complete joint review.
What bolt size is listed?
The reference lists 7/8 inch UNC, or M24, studs with a length of 145. Verify the required bolting configuration against the project specification and mating components.
Can the DWG be used directly for fabrication?
The DWG is provided as a drafting and fabrication reference. Before release, check drawing units, bore selection, mating parts, tolerances, material requirements, weld details, and the latest project documentation.
Does Class 400 alone determine the allowable service?
No. Service suitability depends on the applicable standard, material, temperature, pressure, joint design, and project requirements. Engineering verification is required before installation or use in a pressure piping system.