This reference page summarizes the published dimensions and bolting information for a 20 inch Class 300 blind flange. Use the listed data for preliminary piping layout, drafting, fabrication review, and component comparison, then confirm the project specification before procurement or installation.
A blind flange has no center opening, so its primary function is to close a flanged connection rather than provide a continuous flow passage. The detail is especially useful when reviewing equipment nozzles, maintenance isolation points, pipe-end closures, and future connection locations.
Blind Flange 20″ Class 300
Blind Flange 20″ 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 20″ Class 300 Dimensions
- Reference Standard: ANSI / ASME B16.5
- Nominal Pipe Size (NPS): 20″
- DN Size: DN500
- Flange Thickness: 62mm
- Weight: 230kg
- Stud Bolt Size: 1 1/4″ UNC (or M33) x 205 Long
- Number of Bolts: 24
- Hole Diameter: 1 3/8″ (34.925mm)
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 20″ 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 20″ 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 existing dimension list separates the flange body information from the bolting details. Flange thickness and weight describe the component itself, while stud bolt size, bolt quantity, and hole diameter support the connection layout and drafting review.
When checking a model or drawing, compare the flange designation with the mating flange, gasket arrangement, bolt pattern, and project material requirements. The nominal pipe size and DN designation identify the associated size category; they should not be treated as a substitute for checking the complete flange specification.
Drafting and CAD Coordination
The downloadable DWG can support piping layouts, nozzle arrangements, equipment drawings, and fabrication detailing. Before using the file for release, verify the orientation, mating-face assumptions, connection details, and project-specific revisions against the approved engineering documents.
Related Reference Topics
- Pipe schedules: compare the flange connection with the associated pipe outside diameter and wall specification.
- Flange dimensions: review related flange types when coordinating mating components.
- Gaskets and bolting: confirm the selected sealing and fastening arrangement with the project specification.
- CAD and DWG resources: use related drawing references for layout and detailing coordination.
For final selection, confirm the applicable pressure-temperature requirements, flange material, gasket type, bolt material and length, facing details, and governing project documents. A dimensional reference should be checked by the responsible engineer before fabrication or service use.
Frequently Asked Questions
What is a blind flange used for?
A blind flange closes the end of a piping system, vessel nozzle, valve connection, or other flanged opening. It can also provide an access point for future maintenance or line extension after the connection is properly isolated.
Does a blind flange have a center bore?
No. A blind flange is a solid flange without a center bore, which allows it to block the connected opening when installed with the required gasket and bolting arrangement.
What should be checked before ordering this flange?
Confirm the nominal size, pressure class, facing and gasket requirements, material specification, stud bolt details, hole pattern, and project pressure-temperature requirements. Also check that the mating component uses compatible dimensions.
Can the DWG be used directly for fabrication?
The CAD file can assist with drafting and coordination, but it should be reviewed against the approved project drawings and specifications before fabrication. Confirm any project-specific changes, tolerances, materials, and connection requirements.