This reference provides the dimensional and connection information for a 1/2 inch Class 400 weld neck flange. Use the listed values when reviewing piping layouts, flange details, fabrication drawings, and compatible components.
The page also explains how the tapered hub, bore selection, bolt details, and CAD file relate to practical drafting and piping work. For related terminology, see the PipeSTD references for flange dimensions, pipe schedules, and pipe fittings.
Weld Neck Flange 1/2″ Class 400
Weld Neck Flange 1/2″ Class 400 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 1/2″ Class 400 Dimensions
- Reference Standard: ANSI / ASME B16.5
- Nominal Pipe Size (NPS):1/2″
- DN Size: DN15
- Outside Diameter:95mm
- Flange Thickness:14.2mm
- Hub Diameter:38mm
- Bore Diameter: varies depending on pipe schedule and pipe wall thickness
- Raised Face Diameter:34.9mm
- Weight: 1.5kg
- Number of Bolts:4
- Stud Bolt Size: 1/2″ UNC (or M14) x 75 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 1/2″ Class 400 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 1/2″ Class 400, which can be used for drafting, detailing, piping layout coordination, and fabrication reference.
Available Weld Neck Flange Class 400 Sizes
This size is part of the Weld Neck Flange Class 400 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 dimensional list identifies the flange envelope, hub geometry, face detail, bolt-hole information, and listed weight for this specific size and class. These values should be read together rather than used as isolated dimensions. For example, the flange outside diameter and hole pattern support layout coordination, while the hub and bore relate to the pipe connection and weld preparation.
Bore and Pipe Schedule Coordination
The bore is not treated as a single universal value in this reference because it depends on the selected pipe schedule and wall thickness. Before preparing a fabrication or installation drawing, compare the flange bore with the applicable pipe schedule reference and the actual pipe specification. This check helps prevent a mismatch between the flange, pipe end, and weld detail.
Understanding the Bolt Information
The listed stud bolt size, length, hole diameter, and bolt quantity describe the connection details shown for this flange. Confirm the selected fastener system against the project specification, gasket arrangement, flange facing, and available engagement before procurement or installation. A nominal bolt size alone does not establish the complete assembly requirement.
Why the Weld Neck Hub Matters
A weld neck flange uses a tapered hub to transition from the flange body toward the pipe. The geometry is intended to provide a gradual load path compared with less integrated flange forms, but the final suitability of a connection still depends on material, welding procedure, service conditions, alignment, and engineering review.
Using the CAD Download
The downloadable DWG file can support preliminary layout, drafting, detail coordination, and fabrication reference. Check the drawing units, insertion scale, facing detail, bore selection, and project revision before incorporating the file into controlled design documents. The CAD geometry should be checked against the authoritative dimensional list and project requirements.
Selection Checklist
- Confirm the nominal pipe size and flange class.
- Match the bore to the pipe schedule and wall thickness.
- Check the flange facing and gasket arrangement.
- Verify the bolt pattern, fastener designation, and required length.
- Confirm material, welding, pressure-temperature, and project requirements before fabrication.
Frequently Asked Questions
What is the key feature of a weld neck flange?
Its long tapered hub is welded directly to the pipe and provides a gradual transition between the pipe and flange. This makes the connection geometry important when reviewing stress, welding, and alignment requirements.
What does the bore depend on?
The bore depends on the pipe schedule and pipe wall thickness selected for the connection. Always coordinate the flange bore with the actual pipe specification rather than assuming one bore applies to every pipe configuration.
What bolt information is provided?
The reference lists the number of bolts, stud bolt designation and length, and hole diameter for this flange. Confirm the complete fastener and gasket arrangement against the project specification before installation.
Can the DWG file be used for fabrication?
The DWG file is provided as a drafting, layout, coordination, and fabrication reference. Review its scale, units, revision, and geometry against the page data and approved project documents before releasing fabrication work.
Does the Class 400 designation alone confirm suitability?
No. Final suitability requires review of the applicable pressure-temperature conditions, material specification, pipe details, gasket, bolting, welding requirements, and project design criteria.