Use this reference to check the listed dimensions and connection details for a Blind Flange 20 Inch Class 400 before preparing a piping layout, fabrication drawing, or material request. The page brings together the nominal size, DN designation, flange thickness, weight, stud bolt information, bolt count, and hole diameter from the local reference data.
A blind flange has no center bore, so it closes a flanged connection rather than allowing pipe flow through it. For design coordination, compare this page with the project piping specification, the applicable flange-facing requirements, gasket details, and the related pipe dimensions and schedules reference.
Blind Flange 20″ Class 400
Blind Flange 20″ Class 400 is used to seal the end of a piping system or close off a flange connection in Class 400 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 400 Dimensions
- Reference Standard: ANSI / ASME B16.5
- Nominal Pipe Size (NPS): 20″
- DN Size: DN500
- Flange Thickness: 69.8mm
- Weight: 266kg
- Stud Bolt Size: 1 1/2″ UNC (or M39) x 240 Long
- Number of Bolts: 24
- Hole Diameter: 1 3/4″ (41.275mm)
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 400 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 400, which can be used for drafting, detailing, and piping layout coordination.
Available Blind Flange Class 400 Sizes
This size is part of the Blind Flange Class 400 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 the Blind Flange Reference
The source data identifies the flange by both NPS and DN designations. These labels describe the nominal connection size; they should not be treated as a direct measurement of the flange outside dimensions. The listed thickness and weight are useful for drafting, handling, support, and material-planning checks, while the bolt information supports preliminary flange-connection coordination.
- Flange thickness: Use the listed value when checking the flange profile and overall connection arrangement in a drawing.
- Weight: Treat the listed weight as a reference for handling and layout coordination, subject to the supplied flange specification.
- Stud bolt size and length: Confirm the selected fastener description against the project bolting specification, flange assembly, washers, gasket, and required engagement.
- Number of bolts and hole diameter: Use these details when coordinating the bolt circle and matching the blind flange with the mating flange.
Coordination Checks Before Installation
Dimensions alone do not complete a flange selection. Confirm the flange material, facing, gasket type, bolting requirements, corrosion allowance where applicable, and pressure-temperature conditions with the responsible engineering or procurement team. The Class designation should be checked with the applicable material and service conditions rather than interpreted as a standalone allowable pressure.
For drafting workflows, the available CAD/DWG flange reference can help with layout and detailing. Check the downloaded geometry against the project drawing, mating component, orientation requirements, and revision-controlled specifications before issuing fabrication documents. Related references for flange dimensions, pipe schedules, gasket terminology, and piping bolt terminology can provide useful context when coordinating the complete connection.
Blind Flange 20 Inch Class 400 FAQ
What is the purpose of a blind flange?
A blind flange closes the end of a pipeline, vessel nozzle, valve connection, or other flanged opening. It can provide a removable closure for isolation, maintenance, inspection, or a future connection.
What dimensions are listed for this flange?
The reference lists the NPS and DN designations, flange thickness, weight, stud bolt size and length, number of bolts, and hole diameter. Use the source dimension list as the controlling local data for this page.
Does Class 400 alone define the allowable pressure?
No. The applicable pressure-temperature capability depends on the governing standard, flange material, service temperature, facing, and project requirements. Confirm the complete rating basis with the responsible engineer.
Can the CAD file be used directly for fabrication?
The DWG file is provided as a drafting and coordination resource. Review it against the current project specification, mating flange, material requirements, gasket arrangement, and approved fabrication information before use.
What should be checked before ordering?
Confirm the nominal size, flange class, material specification, facing, gasket, bolting, bolt length, quantity, hole details, applicable standard, and project revision. Also verify that the selected blind flange matches the mating connection.