This reference provides the available dimensional data for a Weld Neck Flange 18 Inch Class 150, along with the bolt arrangement, connection details, weight, and CAD resource. Use the listed values as a drafting and coordination reference, then verify them against the project specification before fabrication or installation.
The weld neck configuration is identified by its tapered hub and direct butt-weld connection to the pipe. That geometry makes the flange different from slip-on, socket-weld, and threaded flange types, so the flange style should be confirmed before selecting mating components or preparing fabrication drawings.
Weld Neck Flange 18″ Class 150
Weld Neck Flange 18″ Class 150 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 150 Dimensions
- Reference Standard: ANSI / ASME B16.5
- Nominal Pipe Size (NPS):18″
- DN Size: DN450
- Outside Diameter:635mm
- Flange Thickness:38.1mm
- Hub Diameter:505mm
- Bore Diameter: varies depending on pipe schedule and pipe wall thickness
- Raised Face Diameter:533.4mm
- Weight: 100kg
- Number of Bolts:16
- Stud Bolt Size: 1 1/8″ UNC (or M30) x 145 Long
- Hole Diameter: 1 1/4″ (31.75mm)
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 150 is commonly used for:
- Process piping systems
- Oil and gas lines
- Water and utility piping
- High-temperature 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 150, which can be used for drafting, detailing, piping layout coordination, and fabrication reference.
Available Weld Neck Flange Class 150 Sizes
This size is part of the Weld Neck Flange Class 150 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 section identifies the flange envelope, hub geometry, facing diameter, bolt-hole information, and nominal pipe connection. These details support layout work, preliminary equipment coordination, spool drawing preparation, and CAD modeling.
NPS, DN, and bore selection
NPS and DN identify the nominal pipe size using two commonly used designation systems. They should not be treated as a substitute for checking the actual pipe outside diameter, inside diameter, or wall thickness. The bore is specifically dependent on the pipe schedule and wall thickness, so the flange bore must be coordinated with the pipe specification rather than assumed from the nominal size alone.
Why the weld neck hub matters
The tapered hub provides a gradual transition between the flange and pipe. In service, this geometry is intended to help distribute stress at the connection, particularly where piping may experience pressure effects, temperature changes, or repeated loading. Welding procedure, alignment, inspection, and material compatibility still require project-specific engineering control.
Bolt and gasket coordination
The bolt count, stud bolt description, and hole diameter in the source data are useful for connection detailing. They should be checked together with the mating flange, gasket selection, washer and nut arrangement, required bolt engagement, and project torque procedure. A correct nominal bolt description alone does not confirm that the complete bolted joint is suitable for service.
Using the CAD download
The downloadable DWG can support piping layouts, flange alignment checks, drafting, and fabrication reference. Before using the drawing in a released document, confirm the selected facing, bore, mating component, and project revision requirements. CAD geometry should not override the project specification or the controlling dimensional reference.
Related reference topics
For broader design and drafting work, link this page with related resources for pipe schedules, flange types, flange facing, stud bolts, gaskets, piping dimensions, and DWG piping details. These topics help readers move from an individual flange reference to the surrounding connection requirements.
Frequently Asked Questions
What is a weld neck flange?
A weld neck flange is a flange with a long tapered hub that is welded directly to the pipe. The hub provides a gradual transition intended to improve stress distribution at the flange-to-pipe connection.
Why does the bore depend on the pipe schedule?
Pipe schedule and wall thickness affect the pipe’s internal opening. Because the flange bore must accommodate the selected pipe, the final bore should be matched to the pipe specification rather than selected from nominal size alone.
Can this flange be used with any Class 150 flange?
The mating flange, facing, gasket, bolt arrangement, materials, and service requirements must be checked together. Confirm compatibility using the applicable project documents and the controlling flange reference before assembly.
What is the DWG file used for?
The DWG file can assist with drafting, piping layout coordination, flange alignment, and fabrication reference. Review the drawing against the required bore, facing, mating component, and project revision before release.
Should the listed bolt size be used without further checking?
No. The listed stud bolt information should be coordinated with the mating flange, gasket, joint configuration, bolt engagement, material requirements, and installation procedure.