This reference page provides dimension, weight, bolting, and CAD information for a Weld Neck Flange 1 1/4 Inch Class 1500. Use the listed values as a dimensional reference when reviewing piping layouts, fabrication drawings, and flange connection details.
A weld neck flange is normally selected when the connection requires a welded transition between the pipe and flange. The tapered hub supports a gradual load path, while the flange face and bolt pattern provide the interface for the mating flange, gasket, and bolting assembly.
Weld Neck Flange 1 1/4″ Class 1500
Weld Neck Flange 1 1/4″ Class 1500 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 1/4″ Class 1500 Dimensions
- Reference Standard: ANSI / ASME B16.5
- Nominal Pipe Size (NPS):1 1/4″
- DN Size: DN32
- Outside Diameter:159mm
- Flange Thickness:28.6mm
- Hub Diameter:64mm
- Bore Diameter: varies depending on pipe schedule and pipe wall thickness
- Raised Face Diameter:63.5mm
- Weight: 4.1kg
- Number of Bolts:4
- Stud Bolt Size: 7/8″ UNC (or M24) x 125 Long
- Hole Diameter: 1″ (25.4mm)
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 1/4″ Class 1500 is commonly used for:
- Process piping systems
- Oil and gas lines
- Refinery and petrochemical piping
- Extremely 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 1/4″ Class 1500, which can be used for drafting, detailing, piping layout coordination, and fabrication reference.
Available Weld Neck Flange Class 1500 Sizes
This size is part of the Weld Neck Flange Class 1500 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 Flange Reference
The source data below identifies the nominal size, DN designation, flange geometry, hub information, bolt-hole details, and approximate component weight. These dimensions should be read together rather than treated as isolated values. For example, the flange outside diameter and bolt-hole arrangement help with layout coordination, while the bore must be checked against the selected pipe schedule and wall thickness.
Nominal Size, DN, and Bore
NPS and DN are nominal designations used to identify the connected pipe size. They do not by themselves define the actual inside diameter of the flange bore. The bore is dependent on the pipe schedule and wall thickness, so the mating pipe specification should be confirmed before fabrication or procurement.
Bolting and Mating Components
The listed stud bolt size, bolt-hole diameter, and number of bolts describe the flange bolting arrangement. Confirm that the mating flange uses a compatible facing, bolt pattern, gasket, and material specification. Bolt length may also require review when the flange is assembled with a gasket, washers, or a different mating component.
CAD and Related References
Use the downloadable DWG as a drafting and layout reference, not as a substitute for project checking. It can support flange orientation, clearance review, piping arrangement, and fabrication detailing. For related design work, link this page with the site’s pipe schedule references, flange dimension resources, piping terminology guides, and CAD/DWG downloads.
Before release for fabrication or installation, verify the project specification, applicable pressure-temperature requirements, material, pipe schedule, gasket selection, flange facing, and current design or inspection requirements.
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. Its geometry provides a gradual transition between the pipe and flange and is commonly reviewed for systems involving pressure, temperature changes, or cyclic loading.
What does Class 1500 identify?
Class 1500 identifies the flange pressure class designation. The allowable service condition still depends on factors such as material, temperature, applicable requirements, and the complete piping design, so the class should not be used alone to determine suitability.
Why can the bore vary for this flange?
The bore is selected to correspond with the connected pipe’s schedule and wall thickness. Confirming the pipe specification is therefore necessary before finalizing the flange bore or weld preparation.
What should be checked before ordering the flange?
Check the nominal size, flange class, facing, material, bore, bolt-hole arrangement, stud bolt details, gasket requirements, and mating flange compatibility. Also review the project specification and applicable pressure-temperature requirements.
What is the DWG file used for?
The DWG file supports drafting, piping layout coordination, dimensional review, and fabrication reference. It should be checked against the approved project requirements before it is used for final fabrication or installation documentation.