This reference provides the dimensional data, bolt information, weight, and CAD resource for a Weld Neck Flange 1 1/2 Inch Class 300. Use the listed values when checking piping layouts, flange connections, fabrication drawings, and component selections.
The bore is not a single fixed value for every installation because it depends on the pipe schedule and wall thickness. Confirm the mating pipe, flange facing, gasket arrangement, and bolting requirements before releasing a drawing or proceeding with fabrication.
Weld Neck Flange 1 1/2″ Class 300
Weld Neck Flange 1 1/2″ 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 1/2″ Class 300 Dimensions
- Reference Standard: ANSI / ASME B16.5
- Nominal Pipe Size (NPS):1 1/2″
- DN Size: DN40
- Outside Diameter:155mm
- Flange Thickness:19mm
- Hub Diameter:70mm
- Bore Diameter: varies depending on pipe schedule and pipe wall thickness
- Raised Face Diameter:73mm
- Weight: 2.7kg
- Number of Bolts:4
- Stud Bolt Size: 3/4″ UNC (or M20) x 90 Long
- Hole Diameter: 7/8″ (22.225mm)
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 1/2″ 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 1/2″ 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 nominal size identifies the connected piping size, while the Class 300 designation identifies the flange pressure class used for component selection and system documentation. These designations should be checked against the project piping specification rather than treated as a complete pressure-temperature design basis.
Checking the Dimensional Data
Review the outside diameter, flange thickness, hub diameter, raised face diameter, bolt-hole information, and listed weight together. The bore requires separate verification because the correct opening must correspond with the pipe schedule and actual wall thickness. A mismatch can affect fit-up, internal alignment, and drawing accuracy.
Weld Neck Geometry and Installation
The tapered hub transitions from the flange body toward the pipe and is intended to be welded directly to the pipe. During detailing, show the flange orientation, weld connection, raised face, bolt-hole pattern, and mating component clearly. The final weld preparation and fabrication procedure remain subject to the applicable project requirements and qualified fabrication practices.
Bolting and Gasket Coordination
Use the listed stud bolt size, length, hole diameter, and bolt count as the starting point for connection detailing. Confirm that the selected gasket, nuts, washers, flange facing, and available thread engagement are compatible with the complete joint. Bolt length should not be confirmed from flange data alone when other joint components affect the assembled thickness.
CAD and Related References
The downloadable DWG can support piping layout coordination, drafting, and fabrication reference. For a complete connection review, pair this resource with the relevant pipe schedule data, flange terminology, gasket information, and other Class 300 flange sizes available on the site. CAD geometry should be checked against the project specification before it is used for manufacture.
Frequently Asked Questions
What is the nominal size of this weld neck flange?
The flange is identified as NPS 1 1/2 inch and DN40.
What is the bore diameter?
The bore varies with the pipe schedule and pipe wall thickness. Select or verify the bore against the actual mating pipe rather than assuming that one bore applies to every installation.
What bolt size is listed for this flange?
The reference lists 3/4 inch UNC, or M20, stud bolts with a listed length of 90. Confirm the final bolting arrangement against the gasket, mating flange, washers, nuts, and project requirements.
How many bolts are listed?
The dimensional reference lists 4 bolts. The bolt-hole diameter is listed separately and should be checked when coordinating the mating flange.
What does the weld neck hub do?
The long tapered hub provides a gradual transition between the flange and pipe. This geometry is intended to reduce stress concentration at the flange base compared with less gradual connection forms, subject to proper design, welding, and installation.
Is the listed weight suitable for lifting or support design?
The listed weight is a component reference value. Lifting plans, pipe supports, transportation, and installation checks should account for the complete assembly and project-specific conditions.