This reference provides dimension and drafting information for a Weld Neck Flange 1 Inch Class 900. Use the source data below to review the flange envelope, hub, raised face, bolt arrangement, stud bolt information, and listed weight before coordinating a piping model or fabrication detail.
The flange dimensions should be read together with the connected pipe schedule, flange facing requirements, gasket selection, material specification, and project pressure-temperature requirements. The bore is not a universal value in this reference because it depends on the pipe schedule and wall thickness selected for the connection.
Weld Neck Flange 1″ Class 900
Weld Neck Flange 1″ Class 900 is widely used in piping systems that require strong, leak-resistant flange connections under high-pressure service. It features a long tapered hub that provides excellent stress distribution and is commonly applied in process piping, utility lines, refineries, power plants, and industrial systems where welding strength and reliability are essential.
This dimension data is based on ANSI / ASME B16.5-2020.
Weld Neck Flange 1″ Class 900 Dimensions
- Reference Standard: ANSI / ASME B16.5
- Nominal Pipe Size (NPS):1″
- DN Size: DN25
- Outside Diameter:149mm
- Flange Thickness:28.6mm
- Hub Diameter:52mm
- Bore Diameter: varies depending on pipe schedule and pipe wall thickness
- Raised Face Diameter:50.8mm
- Weight: 3.6kg
- Number of Bolts:4
- Stud Bolt Size: 7/8″ UNC (or M24) x 125 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 1″ Class 900 is commonly used for:
- Process piping systems
- Oil and gas lines
- Refinery and petrochemical piping
- Very 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 1″ Class 900, which can be used for drafting, detailing, piping layout coordination, and fabrication reference.
Available Weld Neck Flange Class 900 Sizes
This size is part of the Weld Neck Flange Class 900 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 welded directly to the pipe through its tapered hub. When reviewing the listed dimensions, separate the flange geometry from the pipe connection details: the outside diameter, thickness, hub diameter, raised face, bolt-hole information, and weight describe the flange reference, while the bore must be coordinated with the actual pipe wall and schedule.
Dimension and Bolt-Check Guidance
- Confirm the nominal connection: Match the NPS and DN designation with the piping specification and connected components.
- Check the bore: Select or verify the bore against the pipe schedule and wall thickness rather than assuming the flange bore from the nominal size alone.
- Coordinate bolting: Review the listed stud bolt size, length, bolt count, and hole diameter together with the mating flange and gasket arrangement.
- Review the facing: The raised face dimension is important for gasket and mating-flange coordination, but it does not replace a project-specific facing check.
- Use the CAD file carefully: The DWG is useful for layout, detailing, and coordination. Confirm that the drawing revision and project requirements agree before fabrication.
Useful Related References
For a complete piping check, pair this page with references for pipe schedules, flange facing types, stud bolt dimensions, gasket selection, and CAD flange drawings. A related Class 900 weld neck flange size index can also help when comparing adjacent nominal sizes without substituting values between them.
Frequently Asked Questions
What does the bore depend on for this flange?
The bore varies with the connected pipe schedule and pipe wall thickness. Verify the bore against the actual piping specification before ordering or fabrication.
Why is a weld neck flange used?
A weld neck flange has a long tapered hub that is welded to the pipe. This configuration is intended to provide a gradual transition and help manage stress at the flange-to-pipe connection.
What should be checked before using the listed bolt size?
Check the mating flange, gasket arrangement, bolt-hole alignment, required engagement, material specification, and project requirements. The listed stud bolt information should not be treated as a substitute for the complete bolting specification.
Can the DWG be used for fabrication?
The DWG can support drafting, layout coordination, and fabrication reference. Before release, confirm the drawing against the applicable project specification, pipe schedule, bore, facing, material, and current design requirements.
Does Class 900 by itself define the complete connection?
No. The flange class identifies the referenced pressure-class series, but the complete connection also depends on material, temperature, facing, gasket, bolting, pipe details, and applicable project requirements.