This reference page provides the dimensional and identification information for a Blind Flange 20 Inch Class 900, including the nominal size, flange thickness, weight, bolt arrangement, and hole diameter. Use the listed values as a drafting and procurement reference, then verify them against the project specification before fabrication or installation.
Because a blind flange has no center bore, it closes a piping, equipment, or nozzle connection rather than providing a passage for fluid. The downloadable DWG can support layout coordination and detailing, while the dimension list provides the key information needed for an initial flange review.
Blind Flange 20″ Class 900
Blind Flange 20″ 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 20″ Class 900 Dimensions
- Reference Standard: ANSI / ASME B16.5
- Nominal Pipe Size (NPS): 20″
- DN Size: DN500
- Flange Thickness: 108mm
- Weight: 463kg
- Stud Bolt Size: 2″ UNC (or M52) x 350 Long
- Number of Bolts: 20
- Hole Diameter: 2 1/8″ (53.975mm)
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 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 20″ 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 Use This Blind Flange Reference
Start by confirming that the nominal pipe size and pressure class match the piping system and the mating flange. The page identifies the flange as NPS 20 and DN500, with a Class 900 designation. These identifiers should remain consistent across the piping specification, fabrication drawings, gasket selection, and bolting documentation.
The dimensional list separates flange geometry from connection hardware. Flange thickness and hole diameter describe important physical features, while the stud bolt size, bolt length, and number of bolts describe the bolted joint. Check these details against the mating flange and the approved project specification rather than treating the flange designation alone as a complete installation instruction.
Design and Drafting Checks
- Confirm the flange facing, material specification, gasket type, and pressure-temperature requirements before release for fabrication.
- Verify bolt access and clearance in the piping or equipment layout.
- Check that the selected bolt length is appropriate for the complete joint stack-up, including the flange, gasket, washers where specified, and nut engagement.
- Use the CAD drawing with the listed dimensions for preliminary drafting, then confirm critical interfaces against approved project documents.
Related Reference Topics
For broader piping work, readers may also find value in related references covering flange types, flange facing terminology, pipe schedules, gasket selection, stud bolts, and piping isometric drafting. Comparing other sizes in the Class 900 blind flange series can also help when coordinating connected equipment or future line extensions.
Frequently Asked Questions
What is a 20-inch Class 900 blind flange used for?
It is used to close the end of a piping system or seal a flange connection. Typical uses listed for this component include pipe end closure, equipment isolation, valve and nozzle blanking, maintenance shutdown work, and process or utility piping.
Does a blind flange have a center opening?
No. A blind flange is a solid flange without a center bore. Its purpose is to block the connection rather than allow the pipe contents to pass through.
How many bolts are specified for this flange?
The source data specifies 20 bolts. Confirm the mating flange, bolting specification, tightening procedure, and access requirements before installation.
Is the listed bolt information sufficient for fabrication?
It identifies the stud bolt size and length, but fabrication and installation should also confirm the material specification, nut and washer requirements where applicable, gasket arrangement, joint thickness, and project bolting requirements.
Can the DWG be used as the final fabrication drawing?
The DWG is intended to support drafting, detailing, and piping layout coordination. Final fabrication should be based on approved project documents and verified flange, material, gasket, and bolting requirements.