This reference covers the dimensional and drafting information for a Weld Neck Flange 8 Inch Class 150. Use the source data below when checking flange geometry, bolt-hole coordination, and CAD details for piping layouts.
A weld neck flange is not selected by nominal pipe size alone. The flange must also be coordinated with the pipe schedule, bore, facing arrangement, gasket, bolting, material specification, and project requirements. The listed bore is therefore identified as dependent on the connected pipe wall thickness.
For related design work, compare this reference with your project’s pipe schedule, flange facing, stud bolt dimensions, and CAD/DWG piping resources. These checks help prevent mismatches between the flange drawing and the pipe or fitting being detailed.
Weld Neck Flange 8″ Class 150
Weld Neck Flange 8″ 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 8″ Class 150 Dimensions
- Reference Standard: ANSI / ASME B16.5
- Nominal Pipe Size (NPS):8″
- DN Size: DN200
- Outside Diameter:343mm
- Flange Thickness:26.9mm
- Hub Diameter:246mm
- Bore Diameter: varies depending on pipe schedule and pipe wall thickness
- Raised Face Diameter:269.7mm
- Weight: 20.5kg
- Number of Bolts:8
- Stud Bolt Size: 3/4″ UNC (or M20) x 110 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 8″ 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 8″ 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 Weld Neck Flange Reference
The dimension list identifies the main features needed for drafting and coordination: outside diameter, flange thickness, hub diameter, raised face diameter, bolt count, bolt-hole diameter, and stud bolt details. These values describe the flange connection geometry; they do not replace project-specific material, fabrication, or pressure-temperature verification.
Nominal size and bore selection
NPS and DN are nominal designations used to identify the connected piping size. The actual flange bore must be checked against the pipe schedule and wall thickness because a weld neck flange may require a matching internal profile. Confirm the bore before releasing fabrication drawings or connecting the flange to pipe.
Hub and weld-neck function
The tapered hub provides a gradual transition between the flange body and the pipe. In practical detailing, the hub and weld area should be coordinated with the pipe outside diameter, wall thickness, welding procedure, and inspection requirements established for the project.
Bolting and face coordination
Use the listed bolt count, stud bolt size, bolt length, and hole diameter when checking a mating flange or preparing a CAD assembly. Also verify the raised-face dimensions, gasket selection, washer and nut arrangement, and required tightening procedure rather than assuming that every Class 150 connection uses identical project hardware.
CAD and drafting workflow
- Confirm the flange orientation and centerline before placing it in a piping layout.
- Match the flange bore to the selected pipe schedule.
- Check bolt-hole alignment with the mating flange.
- Use the downloadable DWG as a drafting reference and validate it against the project specification before fabrication.
- Keep the flange reference coordinated with related pipe dimensions, fittings, gaskets, and flange terminology pages.
The dimensional values on this page are the local reference data for this component. For installation or fabrication, confirm the applicable standard, material grade, gasket type, bolt specification, and current project requirements.
Frequently Asked Questions
What does a weld neck flange do?
A weld neck flange connects to the pipe through a butt-welded tapered hub. Its long hub provides a gradual transition between the pipe and flange, which helps manage stress at the connection.
Why does the bore vary for this flange?
The bore depends on the connected pipe schedule and wall thickness. Select or verify the bore only after identifying the pipe dimensions used in the project.
Can the listed bolt details be used for fabrication?
The listed bolt count, stud bolt size, length, and hole diameter are useful for dimensional coordination. Fabrication should still confirm the mating flange, gasket, material requirements, tightening method, and project specification.
Is the downloadable DWG ready for construction?
The DWG is provided as a drafting and layout reference. Check its geometry against the page data, the mating components, and the approved project requirements before using it for fabrication or construction documentation.
What should be checked before installation?
Verify the pipe schedule and bore, flange material, face and gasket arrangement, bolt compatibility, bolt length, welding requirements, and applicable pressure-temperature requirements.