This reference provides the dimensional data, bolt information, and CAD resource for a Weld Neck Flange 5 Inch Class 300. Use the listed values for drafting and component identification, then verify the final selection against the project specification and applicable piping requirements.
For related design work, compare this flange with the site’s pipe schedule, flange dimensions, raised-face flange, and piping terminology references. These resources help connect the flange geometry with the pipe wall, gasket, bolts, and mating components used in an assembly.
Weld Neck Flange 5″ Class 300
Weld Neck Flange 5″ Class 300 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 300 Dimensions
- Reference Standard: ANSI / ASME B16.5
- Nominal Pipe Size (NPS):5″
- DN Size: DN125
- Outside Diameter:279mm
- Flange Thickness:33.3mm
- Hub Diameter:178mm
- Bore Diameter: varies depending on pipe schedule and pipe wall thickness
- Raised Face Diameter:185.7mm
- Weight: 15.9kg
- Number of Bolts:8
- Stud Bolt Size: 3/4″ UNC (or M20) x 120 Long
- Hole Diameter: 7/8″ (22.225mm)
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 300 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 300, which can be used for drafting, detailing, piping layout coordination, and fabrication reference.
Available Weld Neck Flange Class 300 Sizes
This size is part of the Weld Neck Flange Class 300 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 Read This Flange Reference
The nominal pipe size identifies the intended piping size, while the DN designation provides the corresponding metric reference. The outside diameter, thickness, hub diameter, and raised-face diameter describe the principal flange geometry used in layout and detailing work.
The bore is not a single universal value for every installation. It must be checked against the selected pipe schedule and wall thickness so the flange bore matches the pipe and does not create an unwanted internal step. This is especially important when coordinating weld-neck flanges with pipe, fittings, valves, and other flanged equipment.
Weld-Neck Geometry and Connection Function
The tapered hub transitions from the flange body toward the pipe. The pipe is welded directly to the hub, so the weld preparation and fit-up should be coordinated with the pipe specification and fabrication procedure. The flange face, gasket, studs, and mating flange must also be reviewed as one connection rather than as isolated parts.
Using the CAD File
The downloadable DWG is useful for preliminary drafting, piping layout coordination, equipment modeling, and fabrication reference. Before issuing a drawing, check the selected facing, bore, bolt-hole arrangement, gasket interface, and mating component. CAD geometry should support the engineering review; it should not replace verification of material, service conditions, or the governing project specification.
Practical Coordination Checklist
- Confirm the pipe schedule and resulting bore.
- Check the flange material and project specification.
- Coordinate the raised face and gasket selection with the mating flange.
- Verify stud diameter, length, hole clearance, and installation access.
- Review the applicable pressure-temperature requirements before procurement or fabrication.
- Use the related flange and pipe references when comparing adjacent components in the piping system.
Frequently Asked Questions
What does a weld-neck flange do?
A weld-neck flange connects to the pipe through a butt weld at its tapered hub. Its geometry provides a gradual transition between the pipe and flange, which is useful when the connection must be reviewed for strength, alignment, and cyclic service conditions.
Does the listed bore apply to every pipe schedule?
No. The bore varies with the pipe schedule and wall thickness. Confirm the selected pipe dimensions before using the flange for fabrication or final detailing.
Is Class 300 a universal pressure value?
No. The class designation should not be treated as one fixed allowable pressure for every material or temperature. Confirm the applicable pressure-temperature rating using the governing standard, material specification, and project requirements.
What should be checked before ordering the flange?
Confirm the nominal size, flange class, material, facing, bore, gasket arrangement, bolt details, and mating component. Also verify that the selected part agrees with the piping specification and service conditions.
What is the DWG file useful for?
The DWG can support drafting, layout coordination, detailing, and fabrication reference. Review the geometry against the approved design and supplier information before releasing construction documents.