This reference provides the dimensional details, bolt information, weight, and CAD resource for a Weld Neck Flange 1/2 Inch Class 900. Use the listed values when checking a drawing, preparing a piping layout, or comparing flange details with the connected pipe and gasket arrangement.
Because a weld neck flange is welded directly to the pipe, its dimensions should be reviewed together with the pipe schedule, bore, welding details, facing arrangement, and project material requirements. The flange class should also be checked against the applicable pressure-temperature design conditions rather than treated as a standalone design approval.
Weld Neck Flange 1/2″ Class 900
Weld Neck Flange 1/2″ 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 1/2″ Class 900 Dimensions
- Reference Standard: ANSI / ASME B16.5
- Nominal Pipe Size (NPS):1/2″
- DN Size: DN15
- Outside Diameter:121mm
- Flange Thickness:22.4mm
- Hub Diameter:38mm
- Bore Diameter: varies depending on pipe schedule and pipe wall thickness
- Raised Face Diameter:34.9mm
- Weight: 1.8kg
- Number of Bolts:4
- 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 1/2″ 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 1/2″ 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 Weld Neck Flange Reference
The dimension list identifies the main geometry needed for drafting and coordination. Outside diameter and thickness describe the flange body, while hub diameter and the tapered hub describe the transition toward the pipe. The raised face diameter identifies the sealing-face area that must be coordinated with the selected gasket and mating flange.
Bore and Pipe Schedule
The bore is not a universal value for every pipe connection. It depends on the pipe schedule and wall thickness selected for the assembly. For that reason, the bore should be confirmed from the connected pipe specification before fabrication or detailed modeling. This is especially important when using the CAD file for a specific piping arrangement.
Bolt and Hole Coordination
The bolt count, stud bolt size, bolt length, and hole diameter should be checked as one connection set. Confirm that the mating flange uses the same bolt pattern and that the selected gasket, washers, nuts, and available tool clearance are compatible with the project requirements. The listed UNC and metric designation should not be mixed without confirming the project standard and procurement requirements.
Using the CAD Drawing
The downloadable DWG can support drafting, preliminary layout, detailing, and coordination. Before issuing a fabrication drawing, compare the file with the page dimensions, connected pipe schedule, flange facing requirements, material specification, and the governing project documents. A CAD model is a reference aid; it does not replace design verification or fabrication review.
Related Reference Topics
- Compare this entry with other Class 900 weld neck flange dimensions when checking size continuity within a piping system.
- Review related pipe schedules and bore dimensions before selecting the flange bore for a drawing.
- Use a flange terminology reference to distinguish raised face, hub, bore, bolt circle, and bolt-hole details.
- Check related flange and fitting CAD resources when coordinating a complete piping layout.
Frequently Asked Questions
What is the primary purpose of a weld neck flange?
A weld neck flange connects to the pipe through a butt weld and uses a tapered hub to provide a gradual transition between the pipe and flange. This configuration is commonly selected where connection strength, alignment, and resistance to service-related stress are important.
What does NPS 1/2 correspond to on this page?
The reference identifies the flange as NPS 1/2 and also lists its DN designation. These size labels describe the nominal connection size; they should not be used as the actual bore without checking the selected pipe schedule.
Why does the bore vary with pipe schedule?
Pipe schedules use different wall thicknesses for a nominal pipe size. Since the inside diameter changes with wall thickness, the flange bore must be matched to the pipe specification used in the assembly.
What bolt information is provided?
The reference lists the number of bolts, stud bolt designation, bolt length, and hole diameter. Confirm these details against the mating flange, gasket arrangement, material requirements, and project bolting practice before ordering or installation.
Can the DWG file be used directly for fabrication?
The DWG is useful for drafting and coordination, but it should be checked against the authoritative dimension list and project requirements. Verify the bore, facing, material, pipe schedule, and connection details before releasing fabrication documents.
Does Class 900 alone establish a safe operating pressure?
No. The applicable pressure-temperature rating depends on the relevant standard, material, temperature, and project design conditions. Confirm the complete rating basis with the responsible engineer and project specifications.