This reference provides dimensional and identification data for a Blind Flange 3 1/2 Inch Class 400, including the listed flange thickness, weight, stud bolt information, bolt count, and hole diameter. Use the values below for drafting, preliminary coordination, and component comparison.
A blind flange has no center bore, so it closes a flanged piping connection rather than allowing the pipe to pass through. For related design work, compare this entry with the site’s flange dimensions, piping terminology, and CAD drawing references.
Blind Flange 3 1/2″ Class 400
Blind Flange 3 1/2″ 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 3 1/2″ Class 400 Dimensions
- Reference Standard: ANSI / ASME B16.5
- Nominal Pipe Size (NPS): 3 1/2″
- DN Size: DN90
- Flange Thickness: 35.1mm
- Weight: 13.2kg
- Stud Bolt Size: 7/8″ UNC (or M24) x 140 Long
- Number of Bolts: 8
- Hole Diameter: 1″ (25.4mm)
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 1/2″ 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 3 1/2″ 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 Use This Blind Flange Reference
The source data identifies the flange by nominal pipe size, DN size, and pressure class. These identifiers should be checked together when matching a blind flange with a mating flange, gasket, bolts, valve, nozzle, or other piping component. A matching nominal size alone does not confirm that the complete connection is suitable.
Dimension and Bolt Information
The listed thickness and weight describe the blind flange entry in this reference. The stud bolt size, bolt length, number of bolts, and hole diameter are provided to support drawing preparation and connection coordination. Before releasing a fabrication drawing, verify the bolt material, thread details, gasket arrangement, facing requirements, and the mating flange information against the project specification.
Class 400 Selection Considerations
The Class 400 designation should be reviewed with the applicable material specification and pressure-temperature requirements. It should not be treated as an independent approval for a piping system. Actual selection also depends on service conditions, flange materials, gasket performance, bolting, joint assembly, and project design requirements.
CAD and Layout Use
The downloadable DWG can help with drafting, equipment connection layouts, piping arrangement work, and coordination around a flange joint. Treat the drawing as a dimensional reference and confirm that its units, layer conventions, facing details, and project revision requirements align with the current design package.
Related Reference Topics
- Blind flange dimensions and identification
- Flange bolting and gasket coordination
- Pipe size and DN terminology
- CAD blocks for piping and flange layouts
Frequently Asked Questions
What is a blind flange used for?
A blind flange closes the end of a pipe, vessel nozzle, valve connection, or other flanged opening. It can support isolation, maintenance access, inspection planning, or a future connection, subject to the project design.
Does a blind flange have a center bore?
No. A blind flange is a solid flange without a center bore. Its purpose is to blank or close a flanged opening.
What bolt information is listed for this flange?
The source entry lists the stud bolt size, an alternative metric designation, bolt length, number of bolts, and hole diameter. Confirm the final bolting arrangement with the mating flange, gasket, material specification, and installation requirements.
Can the DWG be used directly for fabrication?
The DWG is intended to support drafting, detailing, and piping layout coordination. Before fabrication, check the drawing against the current project specification, required flange details, material requirements, and approved design documents.
What should be verified before installation?
Confirm the latest project requirements, flange material, gasket type, bolt length, mating connection, and applicable pressure-temperature rating before fabrication or installation.