This reference page provides dimension, weight, bolting, and CAD information for a 3 inch Class 2500 weld neck flange. Use the source data for preliminary layout, drafting, flange selection review, and fabrication coordination.
The flange dimensions should be read together with the pipe schedule, bore requirement, gasket arrangement, material specification, and project pressure-temperature requirements. For related design work, compare this reference with pages covering pipe schedules, flange classes, stud bolts, gaskets, and CAD/DWG piping details.
Weld Neck Flange 3″ Class 2500
Weld Neck Flange 3″ 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 3″ Class 2500 Dimensions
- Reference Standard: ANSI / ASME B16.5
- Nominal Pipe Size (NPS):3″
- DN Size: DN80
- Outside Diameter:305mm
- Flange Thickness:66.5mm
- Hub Diameter:133mm
- Bore Diameter: varies depending on pipe schedule and pipe wall thickness
- Raised Face Diameter:127mm
- Weight: 39kg
- Number of Bolts:8
- Stud Bolt Size: 1 1/4″ UNC (or M33) x 220 Long
- Hole Diameter: 1 3/8″ (34.925mm)
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 3″ 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 3″ 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 Read This Weld Neck Flange Reference
The dimension list identifies the principal geometry needed to coordinate the flange with adjoining piping and fittings. Outside diameter, thickness, hub diameter, raised face diameter, bolt-hole information, and stud-bolt details support layout and detailing work, while the weight can assist with handling and preliminary material planning.
Bore and Pipe Schedule Coordination
The bore is not a single universal value for this flange designation. It varies with the selected pipe schedule and wall thickness, so the flange bore must be checked against the actual pipe specification before fabrication. This is an important coordination point when connecting the flange to pipe, valves, reducers, or other flanged components.
Bolting and Joint Assembly
The reference identifies the bolt count, stud-bolt designation, bolt length, and hole diameter. These details should be checked against the selected gasket, flange facing, washer arrangement, thread engagement, and the project assembly procedure. Do not treat the bolt information as a substitute for the applicable purchasing or installation specification.
Why the Weld Neck Design Matters
The tapered hub provides a gradual transition from the flange body to the pipe and is intended to reduce stress concentration at the connection. The weld detail, alignment, material compatibility, inspection requirements, and applicable pressure-temperature limits still require review by the responsible engineering and fabrication teams.
Using the CAD File
The downloadable DWG can support drafting, piping layout coordination, and fabrication reference. Before using it in a production drawing, confirm units, insertion scale, layer information, bore selection, facing details, and any project-specific modifications. Related internal references for flange CAD blocks, pipe dimensions, and piping drafting terminology can help complete the surrounding design.
Frequently Asked Questions
What information does this page provide?
It provides the listed dimensions, weight, bolt-hole information, stud-bolt details, weld neck flange description, and a CAD download reference for the 3 inch Class 2500 designation.
Why does the bore depend on the pipe schedule?
The flange bore must accommodate the selected pipe wall thickness and internal diameter. Because pipe schedules can differ, the correct bore must be confirmed against the pipe specification rather than assumed from the nominal pipe size alone.
Can the DWG be used directly for fabrication?
The DWG is useful as a drafting and coordination reference. Fabrication use requires verification of the drawing units, bore, weld preparation, material, gasket arrangement, bolting, tolerances, and project requirements.
What should be checked before ordering or installing the flange?
Confirm the material specification, pipe schedule, bore, gasket type, bolt length, facing arrangement, and applicable pressure-temperature requirements. The responsible engineer or project specification should resolve any conflict between reference data and job requirements.