This reference page provides the source dimensions and identification details for a Weld Neck Flange 8 Inch Class 900. Use the dimensional list for preliminary drafting, flange selection, and coordination with related piping components, while treating project specifications and engineering review as controlling requirements.
The most important selection checks are the nominal size, pressure class, flange type, pipe schedule, bore, gasket arrangement, and bolting. The source data identifies the flange standard and provides the principal dimensions, bolt information, and weight for this flange entry.
Weld Neck Flange 8″ Class 900
Weld Neck Flange 8″ Class 900 is widely used in piping systems that require strong, leak-resistant flange connections under high-pressure service. It features a long tapered hub that provides excellent stress distribution and is commonly applied in process piping, utility lines, refineries, power plants, and industrial systems where welding strength and reliability are essential.
This dimension data is based on ANSI / ASME B16.5-2020.
Weld Neck Flange 8″ Class 900 Dimensions
- Reference Standard: ANSI / ASME B16.5
- Nominal Pipe Size (NPS):8″
- DN Size: DN200
- Outside Diameter:470mm
- Flange Thickness:63.5mm
- Hub Diameter:298mm
- Bore Diameter: varies depending on pipe schedule and pipe wall thickness
- Raised Face Diameter:269.7mm
- Weight: 91kg
- Number of Bolts:12
- Stud Bolt Size: 1 3/8″ UNC (or M36) x 220 Long
- Hole Diameter: 1 1/2″ (38.1mm)
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 900 is commonly used for:
- Process piping systems
- Oil and gas lines
- Refinery and petrochemical piping
- Very high-pressure 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 900, which can be used for drafting, detailing, piping layout coordination, and fabrication reference.
Available Weld Neck Flange Class 900 Sizes
This size is part of the Weld Neck Flange Class 900 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 Flange Reference
NPS identifies the nominal pipe size used in the piping system, while DN provides the corresponding metric designation. These labels identify the connection size; they should not be treated as the flange bore. The bore must be checked against the mating pipe outside diameter, wall thickness, and applicable pipe schedule.
The Class 900 designation identifies the flange pressure class used for specification and compatibility checks. It is not, by itself, a universal allowable working pressure. Pressure-temperature limits depend on the applicable material, temperature, governing specification, and project requirements.
A weld neck flange has a tapered hub that transitions into the pipe. The pipe is welded to the hub, so fabrication details, weld preparation, alignment, inspection, and material compatibility should be confirmed before manufacturing or installation. The flange face and gasket arrangement must also match the mating flange.
Using the Dimension List for Drafting
- Use the outside diameter, thickness, hub dimensions, face dimension, and bolt-hole information when preparing a layout or detail.
- Confirm the bore from the selected pipe schedule rather than assuming that the nominal size defines the opening.
- Coordinate the bolt count, stud size, hole diameter, bolt-circle geometry, gasket, and mating flange before releasing fabrication drawings.
- Use the downloadable DWG as a drafting reference and verify its geometry against the project specification and approved engineering documents.
For related reference work, compare this entry with the site’s pipe schedules, flange dimensions, stud bolt references, gasket terminology, and CAD/DWG piping resources. Those references can help coordinate the flange with the pipe and connected components without substituting for project verification.
Frequently Asked Questions
What does NPS mean on this flange reference?
NPS is the nominal pipe size designation used to identify the connected piping size. The corresponding DN designation is also provided in the source dimensions.
Does the nominal size determine the flange bore?
No. The bore varies with the pipe schedule and pipe wall thickness. Confirm the bore against the actual pipe specification before fabrication or installation.
What is the purpose of the weld neck hub?
The long tapered hub provides the transition from the flange to the pipe and is intended to support a welded connection. Its geometry is associated with stress distribution at the flange-to-pipe transition.
Can the listed stud bolt information be used for every installation?
Use the listed bolting as reference data for this flange entry, then confirm bolt material, length, thread requirements, gasket compression, joint assembly procedure, and project specifications for the actual installation.
What should be checked before using the DWG file?
Verify the drawing against the approved flange specification, selected pipe schedule, mating flange, gasket, bolt arrangement, material requirements, and fabrication tolerances. A CAD file is a drafting aid and does not replace engineering approval.