This reference provides the dimensional and connection details for a Weld Neck Flange 3/4 Inch Class 150, including the flange geometry, bolt arrangement, stud size, hole diameter, and listed weight. Use the data with the project pipe schedule, material specification, gasket requirements, and applicable design documents rather than treating flange dimensions as a complete design approval.
The page is also useful when coordinating piping layouts, checking fabrication drawings, or preparing CAD details. For related guidance, compare this reference with the site’s resources on pipe schedules, flange dimensions, piping terminology, and CAD/DWG piping references.
Weld Neck Flange 3/4″ Class 150
Weld Neck Flange 3/4″ Class 150 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 150 Dimensions
- Reference Standard: ANSI / ASME B16.5
- Nominal Pipe Size (NPS):3/4″
- DN Size: DN20
- Outside Diameter:99mm
- Flange Thickness:11.2mm
- Hub Diameter:38mm
- Bore Diameter: varies depending on pipe schedule and pipe wall thickness
- Raised Face Diameter:42.9mm
- Weight: 0.9kg
- Number of Bolts:4
- Stud Bolt Size: 1/2″ UNC (or M14) x 65 Long
- Hole Diameter: 5/8″ (15.875mm)
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 150 is commonly used for:
- Process piping systems
- Oil and gas lines
- Water and utility piping
- High-temperature 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 150, which can be used for drafting, detailing, piping layout coordination, and fabrication reference.
Available Weld Neck Flange Class 150 Sizes
This size is part of the Weld Neck Flange Class 150 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 dimension list identifies the principal interfaces needed for drafting and fabrication review. The outside diameter and flange thickness describe the main flange envelope, while the hub diameter and raised face diameter help establish the connection geometry. The bolt count, stud bolt designation, and hole diameter are important when checking alignment with the mating flange.
The bore diameter requires particular attention. It varies with the pipe schedule and wall thickness, so the flange selection should be checked against the actual pipe specification before a drawing is released. A nominal pipe size identifies the intended piping size, but it does not by itself define the finished bore for every pipe wall option.
Why the Weld Neck Hub Matters
A weld neck flange uses a tapered hub that transitions into the pipe. The hub provides a gradual load path and supports the welded connection, which is why this flange type is commonly selected for piping systems subject to pressure, temperature changes, or cyclic service. The welding procedure, joint preparation, inspection requirements, and material compatibility still depend on the project specification and applicable engineering review.
Bolting, Gasket, and Mating-Flange Checks
Before installation, confirm that the mating flange has compatible facing, bolt-hole alignment, and fastening requirements. The listed stud bolt designation should be reviewed together with the required bolt length, washer arrangement, gasket thickness, flange facing, and joint assembly procedure. These checks are especially important when a drawing uses alternate inch or metric bolting terminology.
Using the CAD Download
The downloadable DWG can support layout coordination, drafting, detailing, and fabrication reference. Treat the file as a geometry aid and verify its dimensions against the page data and the project specification before using it for manufacture. The final drawing should also identify the pipe schedule, bore condition, material, facing, gasket, and bolting requirements where those items affect the completed joint.
For broader comparison, browse the related Class 150 weld neck flange sizes and other flange CAD downloads on the site. Comparing adjacent sizes can help locate matching reference data, but it should not replace a project-specific compatibility check.
Frequently Asked Questions
What is a weld neck flange?
A weld neck flange is a flanged connection with a long tapered hub that is welded directly to the pipe. Its geometry provides a gradual transition between the pipe and flange and is intended to help manage stress at the connection.
What does the bore depend on for this flange?
The bore depends on the selected pipe schedule and pipe wall thickness. Confirm the actual pipe specification before finalizing the flange bore or fabrication drawing.
What bolt information is provided on this page?
The reference identifies the bolt count, stud bolt designation, and hole diameter for this flange entry. Confirm bolt length, material, washers, gasket thickness, and assembly requirements against the project documents.
Can the listed weight be used for lifting or support design?
The listed weight is a reference value for the flange entry. Lifting plans, pipe-support calculations, shipping arrangements, and assembly assessments should account for the complete connected component and be checked by the responsible engineer.
Is the DWG ready for fabrication without review?
No. The DWG is a drafting and reference resource. Verify the drawing against the dimension data, pipe schedule, material specification, flange facing, gasket, bolting, and applicable project requirements before fabrication.
Where can I find related flange information?
Use the related resources for Class 150 flange sizes, pipe schedules, flange terminology, and piping CAD files to compare compatible reference data and support drawing development.