This reference page provides the dimensional data, connection details, and CAD resource for a Weld Neck Flange 1 Inch Class 300. Use the listed values for drafting and preliminary coordination, then verify the flange, pipe, gasket, bolt, and material requirements against the project specification before fabrication or installation.
The page is especially useful when coordinating pipe schedules, flange dimensions, fittings, and piping layouts. Because the bore depends on the mating pipe wall thickness, the flange dimensions should be reviewed together with the applicable pipe reference rather than treated as an isolated component.
Weld Neck Flange 1″ Class 300
Weld Neck Flange 1″ 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 1″ Class 300 Dimensions
- Reference Standard: ANSI / ASME B16.5
- Nominal Pipe Size (NPS):1″
- DN Size: DN25
- Outside Diameter:124mm
- Flange Thickness:15.7mm
- Hub Diameter:54mm
- Bore Diameter: varies depending on pipe schedule and pipe wall thickness
- Raised Face Diameter:50.8mm
- Weight: 1.4kg
- Number of Bolts:4
- Stud Bolt Size: 5/8″ UNC (or M16) x 75 Long
- Hole Diameter: 3/4″ (19.05mm)
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 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 1″ 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
A weld neck flange has a tapered hub that is welded directly to the pipe. The hub provides a gradual transition between the pipe and flange, which helps manage stress at the connection. This makes the configuration relevant to piping systems exposed to pressure, temperature changes, or repeated loading, subject to engineering verification.
Dimensions and bore selection
The reference list separates the flange geometry from the bore. Outside diameter, thickness, hub diameter, raised face diameter, bolt-hole information, and weight describe the flange entry, while the bore must be coordinated with the pipe schedule and wall thickness. That distinction is important when preparing fabrication drawings or checking fit-up.
Bolting and gasket coordination
The listed bolt quantity, stud bolt description, and hole diameter should be checked against the mating flange and the selected gasket arrangement. Bolt length can be affected by flange facing, gasket thickness, washers, and the engagement required by the connection. Do not select replacement bolts from nominal size alone.
Using the CAD download
The downloadable DWG can support piping layout, equipment coordination, detailing, and fabrication reference. Before using the drawing for manufacture, confirm that its bore, facing, material, and project-specific requirements match the final piping design. Related resources for flange types, pipe fittings, piping terminology, and CAD/DWG references can help complete the design review.
Important verification step
The Class 300 designation and the listed dimensions should not be used by themselves to establish an allowable operating condition. Confirm the applicable pressure-temperature rating, material specification, pipe schedule, gasket, bolting, facing, and governing project requirements before approval.
Frequently Asked Questions
What does a weld neck flange do?
A weld neck flange connects to the pipe through a weld and uses a tapered hub to provide a gradual transition at the flange-to-pipe connection. Its geometry is intended to support a robust, leak-resistant piping connection when properly designed and installed.
Why does the bore vary for this flange?
The bore must correspond to the mating pipe’s schedule and wall thickness. The flange outside geometry can be referenced separately, but the bore should be confirmed before ordering, machining, or fabrication.
Can the listed stud bolts be used with any mating flange?
No. Check the mating flange, hole pattern, gasket arrangement, material requirements, and available thread engagement. The bolt description on this page is a reference for the listed flange, not a substitute for project verification.
What is the CAD file used for?
The DWG file can assist with drafting, piping layout coordination, detailing, and fabrication reference. Review the drawing against the approved dimensional and material requirements before releasing it for manufacture.
Is the Class 300 designation enough to select the flange?
No. Selection also requires review of the applicable standard, material, pipe schedule, bore, gasket, bolting, facing, and pressure-temperature requirements for the service.