This reference page explains the dimensions and identification details for a Blind Flange 1 1/4″ Class 300. Use the source data below when checking flange selection, drafting details, bolt-hole coordination, or a matching CAD layout.
A blind flange has no center bore, so its primary function is to close a flanged connection rather than provide a passage for fluid. In project work, the listed dimensions should be reviewed together with the mating flange, gasket, fasteners, material specification, and the applicable pressure-temperature requirements.
Blind Flange 1 1/4″ Class 300
Blind Flange 1 1/4″ Class 300 is used to seal the end of a piping system or close off a flange connection in Class 300 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 300 Dimensions
- Reference Standard: ANSI / ASME B16.5
- Nominal Pipe Size (NPS): 1 1/4″
- DN Size: DN32
- Flange Thickness: 17.5mm
- Weight: 1.8kg
- Stud Bolt Size: 5/8″ UNC (or M16) x 85 Long
- Number of Bolts: 4
- Hole Diameter: 3/4″ (19.05mm)
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 300 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 300, which can be used for drafting, detailing, and piping layout coordination.
Available Blind Flange Class 300 Sizes
This size is part of the Blind Flange Class 300 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 Use This Blind Flange Reference
The dimensional list identifies the nominal pipe size, DN designation, flange thickness, weight, stud bolt details, bolt count, and hole diameter for this flange entry. These details support common drafting and coordination tasks, including checking whether a blind flange can be represented correctly in a piping arrangement or equipment connection.
Understanding the Bolt Information
The stud bolt description should be read together with the number of bolts and the hole diameter. The bolt size identifies the fastener designation, while the stated length is part of the supplied reference data. Final bolt selection should also account for the flange facing, gasket arrangement, washer use, thread engagement, and project requirements.
Design and Installation Checks
- Confirm that the mating flange uses the same nominal size and pressure class.
- Check flange facing compatibility and select a gasket appropriate to the service.
- Verify the material specification and pressure-temperature requirements before procurement or fabrication.
- Check bolt length and tightening requirements against the complete assembled joint.
- Use the CAD file as a drafting reference, then coordinate it with the project piping and equipment drawings.
Related Reference Topics
This page can be used alongside PipeSTD references for flange dimensions, pipe schedules, flange facings, bolting terminology, piping fittings, and CAD or DWG resources. Reviewing related sizes in the Blind Flange Class 300 series can also help with comparison and selection, while the local dimensional entries remain the controlling reference for each size.
Blind Flange 1 1/4 Inch Class 300 FAQ
What is a blind flange used for?
A blind flange closes the end of a pipeline, vessel nozzle, valve connection, or other flanged opening. It can provide an isolation point and may allow later access for maintenance or line extension.
Does this blind flange have a center bore?
No. A blind flange is a solid flange without a center bore, which distinguishes it from flanges intended to connect directly to a pipe passage.
What bolt information is listed for this flange?
The reference lists 5/8″ UNC, or M16, stud bolts with the stated length, together with four bolts and a 3/4″ (19.05mm) hole diameter. Confirm the complete joint assembly before ordering fasteners.
Is the listed Class 300 designation sufficient for final selection?
No. Final selection should also confirm the flange material, gasket, mating components, service conditions, and applicable pressure-temperature rating. The source notes should be reviewed before fabrication or installation.
Is a CAD file available?
Yes. The page includes a DWG download intended for drafting, detailing, and piping layout coordination. Treat the drawing as a reference and verify it against the project documents.