This reference provides the dimensional data, connection details, and CAD resource for a Weld Neck Flange 2 1/2 Inch Class 2500. Use the listed dimensions for drafting and coordination, then confirm the selected flange, pipe bore, gasket, bolts, and material against the project specification before fabrication or installation.
The page is intended to support piping engineers, designers, detailers, fabricators, and maintenance teams comparing flange dimensions and preparing connection details. For related work, review the site’s resources on pipe schedules, flange types, gaskets, stud bolts, and piping CAD drawings.
Weld Neck Flange 2 1/2″ Class 2500
Weld Neck Flange 2 1/2″ Class 2500 is widely used in piping systems that require strong, leak-resistant flange connections under extremely high-pressure service. It features a long tapered hub that provides excellent stress distribution and is commonly applied in refineries, petrochemical plants, power generation systems, and critical industrial piping where welding strength and connection reliability are essential.
This dimension data is based on ANSI / ASME B16.5-2020.
Weld Neck Flange 2 1/2″ Class 2500 Dimensions
- Reference Standard: ANSI / ASME B16.5
- Nominal Pipe Size (NPS):2 1/2″
- DN Size: DN65
- Outside Diameter:267mm
- Flange Thickness:57.2mm
- Hub Diameter:114mm
- Bore Diameter: varies depending on pipe schedule and pipe wall thickness
- Raised Face Diameter:104.8mm
- Weight: 25.5kg
- Number of Bolts:8
- Stud Bolt Size: 1 1/8″ UNC (or M30) x 195 Long
- Hole Diameter: 1 1/4″ (31.75mm)
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 2500 is commonly used for:
- Process piping systems
- Oil and gas lines
- Refinery and petrochemical piping
- Extremely high-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 2500, which can be used for drafting, detailing, piping layout coordination, and fabrication reference.
Available Weld Neck Flange Class 2500 Sizes
This size is part of the Weld Neck Flange Class 2500 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 Weld Neck Flange Reference
A weld neck flange is aligned with the pipe and joined through its tapered hub. Unlike a loose or slip-on arrangement, the hub-and-weld configuration is intended to provide a more continuous load path between the pipe and flange. The geometry is therefore important when checking fit-up, weld preparation, clearances, and the relationship between the flange bore and the pipe wall.
Check the Bore Against the Pipe Schedule
The bore is not treated as a single universal value in this reference because it varies with the pipe schedule and wall thickness. Before selecting or modeling the flange, identify the pipe specification and schedule used by the project. The bore should then be checked against the actual pipe outside diameter, inside diameter, wall, and welding detail. This is an important distinction when comparing flange dimensions with a nominal pipe size.
Understand the Class Designation
The Class 2500 designation identifies the flange pressure-class category; it should not be treated as a standalone allowable pressure for every service condition. The applicable rating depends on factors such as material, temperature, fluid service, gasket selection, bolting, and the governing project requirements. Confirm the pressure-temperature rating and material compatibility before approving the connection for service.
Use the Bolt Information for Coordination
The listed bolt count, stud size, hole diameter, and stud length are useful for flange drilling, bolt-clearance checks, bill-of-material preparation, and 3D model coordination. Bolt length should still be reviewed with the selected flange thickness, gasket arrangement, washer practice, and required thread engagement. Do not substitute a metric or imperial bolting option without confirming that it matches the project specification.
CAD and Related Reference Work
The downloadable DWG can support piping layout, equipment-interface coordination, detailing, and fabrication reference. Treat the drawing as a dimensional aid rather than a replacement for the approved design documents. When building a flange connection, coordinate this resource with the applicable pipe schedule reference, flange facing information, gasket selection, and bolt-material requirements.
Practical Review Checklist
- Confirm the nominal pipe size and DN designation match the piping line list.
- Match the flange bore to the specified pipe schedule and wall thickness.
- Check the outside diameter, thickness, hub, face, bolt circle, holes, and bolt projection in the fabrication model.
- Verify flange material, facing, gasket, stud material, and pressure-temperature requirements.
- Compare the CAD file with the approved project specification before issuing fabrication documents.
Frequently Asked Questions
What is a weld neck flange?
A weld neck flange has a long tapered hub and is welded directly to the pipe. Its geometry helps transition loads from the flange into the pipe and is commonly considered where connection strength and resistance to cyclic service are important.
Why does the bore depend on the pipe schedule?
Pipe schedules use different wall thicknesses within a nominal pipe size. Because the flange bore must accommodate the selected pipe, the correct bore depends on the actual pipe schedule and wall thickness rather than the nominal size alone.
What information is provided for this Class 2500 flange?
The reference lists the flange dimensions, hub and face information, weight, bolt quantity, stud bolt size and length, and hole diameter. These values are intended for dimensional reference and coordination with the project’s pipe and connection specifications.
Can the DWG be used for fabrication?
The DWG is useful for drafting, layout coordination, and fabrication reference. Final fabrication should use the approved project drawings and confirm material, bore, facing, gasket, bolting, weld details, and applicable rating requirements.
Does Class 2500 define the allowable pressure in every application?
No. The class designation is part of the flange rating system, but the applicable pressure-temperature rating depends on the flange material and service conditions. Confirm the governing rating requirements for the specific application.