This reference page provides the dimensional and connection details for a Weld Neck Flange 20 Inch Class 600. Use the listed values when checking piping layouts, flange arrangements, fabrication drawings, and procurement information against the project requirements.
The page also explains how to read the flange dimensions, why the bore must be matched to the pipe schedule, and how the stud bolt information supports connection detailing. For related design work, compare this reference with the site’s pages on pipe schedules, flange dimensions, and piping terminology.
Weld Neck Flange 20″ Class 600
Weld Neck Flange 20″ Class 600 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 20″ Class 600 Dimensions
- Reference Standard: ANSI / ASME B16.5
- Nominal Pipe Size (NPS):20″
- DN Size: DN500
- Outside Diameter:813mm
- Flange Thickness:88.9mm
- Hub Diameter:610mm
- Bore Diameter: varies depending on pipe schedule and pipe wall thickness
- Raised Face Diameter:584.2mm
- Weight: 368kg
- Number of Bolts:24
- Stud Bolt Size: 1 5/8″ UNC (or M42) x 285 Long
- Hole Diameter: 1 3/4″ (44.45mm)
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 20″ Class 600 is commonly used for:
- Process piping systems
- Oil and gas lines
- Water and utility piping
- 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 20″ Class 600, which can be used for drafting, detailing, piping layout coordination, and fabrication reference.
Available Weld Neck Flange Class 600 Sizes
This size is part of the Weld Neck Flange Class 600 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 Weld Neck Flange Reference
The nominal pipe size identifies the intended piping connection, while the outside diameter, thickness, hub diameter, and raised face diameter describe the flange geometry used for layout and detailing. These dimensions should be read together rather than treated as interchangeable measurements.
The bore diameter is schedule-dependent. It must be coordinated with the actual pipe wall thickness and the selected weld preparation before fabrication. This is an important check when using the flange in a piping model or when matching it to a pipe schedule reference.
The listed bolt count, stud size, bolt-hole diameter, and bolt length are connection-detailing information. Confirm the selected bolting, gasket, flange facing, material specification, and installation requirements with the project documents before ordering or assembly. Bolt length can also depend on the complete joint stack-up, including the mating flange, gasket, and washer arrangement.
Weld Neck Flange Design and Drafting Considerations
The tapered hub transitions from the flange body toward the pipe and is intended to support a welded connection. In a drawing, show the flange face, bolt-hole pattern, hub profile, and pipe interface clearly enough for coordination with the mating component.
For CAD work, the downloadable DWG can support preliminary drafting, piping layout coordination, and fabrication reference. Treat the drawing and dimensional list as reference data: verify the required facing, bore, material, gasket selection, and project-specific tolerances before releasing fabrication documents. Related internal references may include raised-face flanges, stud bolt sizing, pipe flange types, and CAD/DWG piping drawings.
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 geometry provides a gradual transition between the pipe and flange and is commonly selected where a robust welded flange connection is required.
Why does the bore vary with pipe schedule?
The bore has to accommodate the pipe’s internal opening and wall thickness. Because pipe schedules can change the wall dimension for the same nominal size, the correct bore must be confirmed before fabrication or installation.
Does Class 600 alone define the complete flange selection?
No. The flange class identifies the applicable pressure-temperature design classification, but the complete selection also requires confirmation of material, facing, bore, gasket, bolting, temperature, and project requirements.
What is the DWG file used for?
The DWG file can be used as a drafting and coordination reference for layouts, details, and fabrication preparation. It should be checked against the dimensional list and current project requirements before it is used for final fabrication.