This reference provides a practical way to review the dimensional and installation information for a Weld Neck Flange 2 1/2 Inch Class 300. Use the source data below when checking flange layouts, connection details, fabrication drawings, and related pipe dimensions.
A weld neck flange is normally selected when the connection requires a direct butt-welded attachment and a tapered hub for a gradual transition from the flange into the pipe. The flange dimensions should be reviewed together with the pipe outside diameter, wall thickness, gasket arrangement, bolting, and the applicable design conditions.
Weld Neck Flange 2 1/2″ Class 300
Weld Neck Flange 2 1/2″ 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 2 1/2″ Class 300 Dimensions
- Reference Standard: ANSI / ASME B16.5
- Nominal Pipe Size (NPS):2 1/2″
- DN Size: DN65
- Outside Diameter:190mm
- Flange Thickness:23.9mm
- Hub Diameter:100mm
- Bore Diameter: varies depending on pipe schedule and pipe wall thickness
- Raised Face Diameter:104.8mm
- Weight: 5.5kg
- Number of Bolts:8
- Stud Bolt Size: 3/4″ UNC (or M20) x 100 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 2 1/2″ 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 2 1/2″ 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 Weld Neck Flange Reference
The dimensional list identifies the main geometry needed for drafting and coordination. Outside diameter, thickness, hub diameter, raised-face diameter, bolt-circle details, and bolt-hole information affect the space required around the connection and the way it is shown in a piping or fabrication drawing.
Bore and Pipe Schedule
The bore is not treated as a single universal value for this flange size. It must be matched to the pipe schedule or actual wall thickness being used. This is important because the weld-end opening should align with the pipe, and an incorrect bore can create an installation or fabrication problem. Review the related pipe schedule reference before finalizing a weld neck flange detail.
Bolting, Gasket, and Face Details
The bolt count, stud information, hole diameter, and raised-face geometry work together as a connection set. Confirm that the selected gasket matches the facing arrangement and that the bolt length accounts for the flange, gasket, washers where specified, and available thread engagement. Do not treat a bolt size listed for a reference connection as a substitute for project-specific bolting requirements.
Class Designation and Engineering Review
The Class designation identifies the flange pressure-temperature class system; it is not, by itself, a single allowable pressure for every service condition. Material, temperature, corrosion allowance, gasket selection, joint design, and the governing project specification can affect the final application. Use the dimensional data for reference and have the complete connection verified by the responsible engineer.
Using the CAD File
The downloadable DWG can support preliminary layout, detailing, and coordination. Before using it for fabrication, check units, insertion point, layer conventions, bore assumptions, facing details, and compatibility with the selected pipe and gasket. Related flange references and CAD/DWG resources can help maintain consistent drafting practices across a piping model.
Frequently Asked Questions
What is the purpose of the tapered hub?
The tapered hub provides a gradual transition between the pipe and flange body. This geometry helps distribute stress more smoothly than a short, abrupt flange-to-pipe transition.
Does the listed bore apply to every pipe schedule?
No. The bore must be selected or verified against the pipe schedule and wall thickness. Confirm the actual pipe dimensions before ordering, machining, or welding.
Can the DWG be used directly for fabrication?
It can be used as a drafting and coordination reference, but it should be checked against the project specification, drawing units, pipe schedule, gasket arrangement, material requirements, and fabrication procedures before release.
Does Class 300 alone define the allowable working pressure?
No. Allowable pressure depends on the applicable pressure-temperature requirements and other design factors, including material and service conditions. A qualified engineer should verify the complete connection.
What should be checked before installation?
Confirm flange facing, bore alignment, gasket compatibility, bolt and stud requirements, tightening procedure, material specification, and the applicable project or piping standard.