This reference page provides the listed dimensions and connection details for a Weld Neck Flange 3/4 Inch Class 300. Use the dimensional data for preliminary piping layout, flange selection, drafting, and coordination with related pipe and fitting components.
Because a weld neck flange connects directly to the pipe, the flange bore must be reviewed together with the applicable pipe schedule and wall thickness. The flange dimensions, bolt details, and CAD file should be checked against the project specification before fabrication or installation.
Weld Neck Flange 3/4″ Class 300
Weld Neck Flange 3/4″ 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 3/4″ Class 300 Dimensions
- Reference Standard: ANSI / ASME B16.5
- Nominal Pipe Size (NPS):3/4″
- DN Size: DN20
- Outside Diameter:117mm
- Flange Thickness:14.2mm
- Hub Diameter:48mm
- Bore Diameter: varies depending on pipe schedule and pipe wall thickness
- Raised Face Diameter:42.9mm
- 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 3/4″ 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 3/4″ 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 Use This Flange Reference
The dimensional list identifies the main envelope and connection features, including outside diameter, thickness, hub diameter, raised face diameter, bolt-hole information, and listed weight. These values are useful when checking clearances, preparing piping arrangement drawings, and coordinating flange faces with gaskets, bolts, valves, and other fittings.
Bore and Pipe Schedule Coordination
The bore is not treated as a single universal value in the reference data because it varies with pipe schedule and pipe wall thickness. Confirm the mating pipe specification before creating a detailed fabrication drawing. A bore mismatch can affect fit-up, internal alignment, and the final weld preparation.
Bolting and Flange-Face Checks
Use the listed stud bolt size, length, number of bolts, and hole diameter when developing a connection detail. Bolt selection should still be reviewed against the gasket arrangement, flange material, coating or corrosion allowance, tightening procedure, and project requirements. The raised face diameter should be coordinated with the selected gasket and the mating flange.
CAD and Related References
The downloadable DWG can support piping layout, equipment coordination, detail drawings, and fabrication reference. For a complete connection review, link this page with the site’s pipe schedule references, flange dimensions, gasket guides, stud bolt references, and Class 300 flange listings. Comparing the mating components is especially important when the pipe bore or facing arrangement is schedule-dependent.
The designation Class 300 identifies the flange class used in the reference. It should not be used by itself to determine an allowable working condition; material, temperature, gasket, bolting, piping code, and project requirements must also be evaluated by the responsible engineer.
Frequently Asked Questions
What is the bore of a 3/4 Inch Class 300 weld neck flange?
The bore varies according to the pipe schedule and wall thickness. Select or verify the bore only after confirming the mating pipe specification.
What bolt information is listed for this flange?
The reference lists the stud bolt size, bolt length, number of bolts, and hole diameter. Confirm the final bolting arrangement with the gasket, mating flange, material specification, and project tightening requirements.
Why is a weld neck flange used?
A weld neck flange has a tapered hub that is welded directly to the pipe. Its geometry is intended to provide a robust transition between the pipe and flange and to help manage stress at the flange connection.
Can the DWG be used for fabrication?
The DWG is provided as a drafting and fabrication reference. Before release for manufacture, verify the drawing against the project specification, pipe schedule, flange material, gasket selection, bolting, and applicable engineering requirements.
Does Class 300 alone establish the pressure limit?
No. The applicable pressure-temperature condition depends on the flange material and governing requirements, in addition to the class designation. Use the project specification and engineering review to confirm suitability.