This reference provides the dimensional and installation-related information needed to identify a Blind Flange 1 1/4 Inch Class 900 for piping layouts, fabrication review, and maintenance planning. Use the source data below as the local reference for the flange thickness, weight, bolt arrangement, hole size, and stud bolt information.
A blind flange has no center opening for fluid flow. Instead, its solid face closes a flanged connection, allowing a line, nozzle, or equipment opening to be isolated while retaining a bolted connection that can be removed for inspection or future work. For related design work, compare this page with the site’s flange dimensions, pipe schedules, gasket selection, and piping terminology references.
Blind Flange 1 1/4″ Class 900
Blind Flange 1 1/4″ Class 900 is used to seal the end of a piping system or close off a flange connection in Class 900 service. It is a solid flange without a center bore and is commonly used in industrial piping systems, maintenance isolation points, and future pipeline expansion connections where a higher pressure rating is required.
This dimension data is based on ANSI / ASME B16.5-2020.
Blind Flange 1 1/4″ Class 900 Dimensions
- Reference Standard: ANSI / ASME B16.5
- Nominal Pipe Size (NPS): 1 1/4″
- DN Size: DN32
- Flange Thickness: 28.6mm
- Weight: 4.1kg
- Stud Bolt Size: 7/8″ UNC (or M24) x 125 Long
- Number of Bolts: 4
- Hole Diameter: 1″ (25.4mm)
What Is a Blind Flange?
A blind flange is a blank flange used to close the end of a pipeline, vessel nozzle, or equipment connection. It provides a secure shutoff point and is often selected when future maintenance, inspection, or line extension may be required.
Common Applications
Blind Flange 1 1/4″ Class 900 is commonly used for:
- Pipe end closure
- Equipment isolation
- Valve and nozzle blanking
- Maintenance shutdown work
- Process and utility piping systems
- Higher pressure piping applications
CAD Drawing Download
This page includes the CAD drawing file for Blind Flange 1 1/4″ Class 900, which can be used for drafting, detailing, and piping layout coordination.
Available Blind Flange Class 900 Sizes
This size is part of the Blind 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, gasket type, bolt length, and applicable pressure-temperature rating.
How to Read This Blind Flange Reference
The dimensional list identifies the nominal pipe size and its corresponding DN designation, then gives the physical and bolting information used for drafting and coordination. The listed flange thickness and weight are useful for checking handling requirements, layout assumptions, and model data, while the bolt count and hole diameter support connection detailing.
Do not confuse the stud bolt size with the hole diameter. The stud bolt describes the threaded fastener specification and length; the hole diameter describes the clearance opening through the flange. Both items should be checked together with the mating flange, washer arrangement, gasket, and project bolting requirements before fabrication.
Using the CAD File
The downloadable DWG can support preliminary drafting, piping arrangement, equipment-interface coordination, and fabrication detailing. Confirm the drawing orientation, units, flange facing, and connection assumptions before incorporating it into a controlled project model. CAD geometry should be checked against the approved procurement and fabrication documents rather than treated as a substitute for project-specific verification.
Selection and Installation Considerations
- Confirm that the blind flange matches the mating flange designation and facing arrangement.
- Review the material specification, gasket type, bolting requirements, and applicable pressure-temperature limits.
- Check access for bolt installation and removal, especially where the flange will serve as a maintenance isolation point.
- For a permanent closure, temporary blank, or future expansion point, verify the isolation procedure and engineering requirements before work begins.
Readers comparing alternatives may also find the related flange classes, blind flange size series, pipe dimensions and schedules, and CAD/DWG piping references useful for matching components across a project.
Frequently Asked Questions
What is a blind flange used for?
A blind flange closes a pipe end, vessel nozzle, valve connection, or equipment opening. Because it is bolted rather than permanently welded in place, it can be removed for maintenance, inspection, testing, or future line work.
Does a blind flange have a center bore?
No. A blind flange is a solid flange without a flow opening. Its purpose is to block the connected passage at the flanged joint.
What does the Class 900 designation indicate?
The class designation identifies the flange pressure-class category used for compatibility and rating evaluation. It is not, by itself, a universal allowable pressure for every material or operating condition. Material, temperature, gasket, bolting, and project requirements must also be reviewed.
Why are both NPS and DN shown?
NPS and DN are nominal size designations used to identify the connection size in different engineering conventions. They are reference identifiers and should not be treated as a direct statement of the flange’s measured outside diameter.
Can the listed stud bolts be replaced with another size?
Do not substitute bolting without checking the approved flange detail, mating component, gasket, material, tightening procedure, and project specification. Bolt length and thread selection must provide the required engagement without interfering with the assembly.
Is the DWG ready for fabrication?
The DWG is intended as a drafting and coordination resource. Before fabrication, verify its units, geometry, flange facing, material information, and revision against the approved project documents and the applicable procurement requirements.