This reference covers the dimensions, weight, bolting information, and CAD resource for an 18-inch Class 400 weld neck flange. Use the source data below when checking flange layout, pipe connection details, and drafting requirements.
The flange dimensions should be read together with the applicable pipe schedule, flange facing, gasket selection, and project material requirements. These related piping references help explain why the bore and connection details must be confirmed before fabrication.
Weld Neck Flange 18″ Class 400
Weld Neck Flange 18″ 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 18″ Class 400 Dimensions
- Reference Standard: ANSI / ASME B16.5
- Nominal Pipe Size (NPS):18″
- DN Size: DN450
- Outside Diameter:711mm
- Flange Thickness:66.5mm
- Hub Diameter:533mm
- Bore Diameter: varies depending on pipe schedule and pipe wall thickness
- Raised Face Diameter:533.4mm
- Weight: 207kg
- Number of Bolts:24
- Stud Bolt Size: 1 3/8″ UNC (or M36) x 230 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 18″ 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 18″ 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 Use This Weld Neck Flange Reference
A weld neck flange is welded directly to the pipe through its tapered hub. For design review and detailing, the outside diameter, thickness, raised-face diameter, bolt-hole information, and hub geometry describe the flange envelope and connection arrangement.
The listed bore is schedule-dependent rather than a single universal opening. Confirm the mating pipe’s nominal size, schedule, and wall thickness before finalizing the weld preparation or checking internal alignment. This is especially important when coordinating the flange with pipe dimensions and schedules elsewhere in a piping model.
Bolting and Gasket Coordination
The bolt count, stud size, bolt-hole diameter, and stated length should be checked against the selected gasket, flange facing, washers, coating requirements, and the actual joint stack-up. The listed bolt information is a reference for this flange configuration; project specifications and the approved assembly procedure remain controlling.
Using the CAD/DWG File
The downloadable DWG can support drafting, equipment or piping layout coordination, preliminary detailing, and fabrication review. Treat the drawing as a dimensional reference and verify the final connection against the approved flange data, pipe bore, gasket arrangement, and project tolerances before release.
Recommended Related References
- Pipe schedule and pipe wall-thickness references
- Flange types, facings, and pressure-class terminology
- Stud bolts, nuts, washers, and bolt-length selection
- CAD/DWG piping component resources
- Welded pipe joint and fabrication terminology
Frequently Asked Questions
What is a weld neck flange?
A weld neck flange has a long tapered hub and is welded directly to the pipe. The hub provides a gradual transition between the pipe and flange and is intended to support a robust welded connection.
Why does the bore vary for this flange?
The bore depends on the pipe schedule and wall thickness selected for the mating pipe. Confirm the pipe’s actual dimensional reference before fabrication or installation.
What bolting information is provided?
The reference lists the number of bolts, stud bolt size and length, and hole diameter for this flange configuration. Confirm the complete joint assembly against the project specification and gasket requirements.
Can the DWG be used for fabrication?
The DWG is useful for drafting, layout coordination, and fabrication reference. Final fabrication should use the approved project documents and verified flange, pipe, gasket, and bolting information.
What should be checked before installation?
Confirm the flange material, pipe schedule, bore, gasket type, bolt length, facing condition, and applicable pressure-temperature requirements before installation.