This reference page provides the listed dimensions, weight, bolt information, and CAD resource for a Blind Flange 3 Inch Class 300. Use the original dimensional data for drafting and procurement review, then confirm the project specification before fabrication or installation.
A blind flange has no center bore. Unlike a weld neck, slip-on, or threaded flange, it closes a flanged connection rather than allowing the pipe to continue through the flange. This makes it useful where a line, nozzle, or equipment connection must be blanked for isolation, maintenance, or a possible future extension.
Blind Flange 3″ Class 300
Blind Flange 3″ 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 3″ Class 300 Dimensions
- Reference Standard: ANSI / ASME B16.5
- Nominal Pipe Size (NPS): 3″
- DN Size: DN80
- Flange Thickness: 26.9mm
- Weight: 7.3kg
- Stud Bolt Size: 3/4″ UNC (or M20) x 110 Long
- Number of Bolts: 8
- Hole Diameter: 7/8″ (22.225mm)
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 3″ 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 3″ 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 Read This Blind Flange Reference
The source data identifies the nominal pipe size in both NPS and DN terminology. These are nominal designations used to match piping components; they should not be treated as a direct measurement of the flange outside dimensions or the pipe’s actual inside diameter.
The listed flange thickness and weight are useful for layout, material handling, and preliminary purchasing checks. For fabrication, confirm the flange material, facing arrangement, gasket selection, and the applicable pressure-temperature requirements for the service. A Class 300 designation is a standard pressure class identifier, not a universal allowable pressure for every material and temperature combination.
Understanding the Bolt Information
The reference gives the stud bolt designation, an alternate metric designation, the specified length, bolt count, and hole diameter. These details should be checked together with the mating flange. Confirm that the bolt pattern, hole clearance, thread form, washer requirements, and available engagement are compatible with the complete joint assembly.
Drafting and CAD Coordination
The downloadable DWG can support piping layouts, equipment connection details, and preliminary arrangement work. Before issuing a drawing for fabrication, compare the CAD geometry with the listed dimensions and the project flange specification. Also check the gasket and bolting details because a drawing file does not by itself confirm material, facing, or service suitability.
Related Reference Topics
- Use a flange dimensions reference when comparing blind, weld neck, slip-on, socket weld, and threaded flange types.
- Review a pipe schedules guide when coordinating the flange with pipe wall thickness and nominal size.
- Consult a gasket and bolting reference when preparing a complete flange joint detail.
- Browse the Class 300 flange size category for matching dimensions and CAD resources.
Frequently Asked Questions
What is a blind flange used for?
A blind flange closes the end of a piping system or a flanged equipment connection. It can provide a removable blanking point for isolation, maintenance, inspection, or future line work.
Does a blind flange have a pipe bore?
No. A blind flange is solid across its center and does not provide a passage for fluid. The sealing face and bolting arrangement connect it to the mating flange.
What does Class 300 mean?
Class 300 identifies the flange pressure class within the applicable dimensional and rating system. The allowable service condition still depends on material, temperature, design requirements, gasket selection, and the governing project specification.
Can the listed stud bolts be used for every installation?
Not automatically. Verify the mating flange, gasket, washers if required, thread compatibility, bolt engagement, corrosion requirements, and project bolting specification before installation.
Is the DWG ready for fabrication without review?
No. Use the DWG as a drafting and coordination reference, then verify its geometry against the source dimensions, mating components, material requirements, facing details, and approved project drawings.