This reference provides dimension and drafting information for a Blind Flange 3 1/2 Inch Class 600, including its nominal size designation, thickness, weight, bolting details, and hole diameter. Use the values below when reviewing piping layouts, flange details, and connection drawings.
A blind flange has no center bore, so it closes a flanged connection rather than providing a passage for fluid. The flange can be used at a pipe end, equipment connection, or temporary or permanent isolation point, subject to the project design and applicable pressure-temperature requirements.
Blind Flange 3 1/2″ Class 600
Blind Flange 3 1/2″ Class 600 is used to seal the end of a piping system or close off a flange connection in Class 600 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 600 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 600 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 600, which can be used for drafting, detailing, and piping layout coordination.
Available Blind Flange Class 600 Sizes
This size is part of the Blind Flange Class 600 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 flange by both NPS and DN designations. These are nominal pipe-size references used for coordination; they should not be treated as a substitute for checking the actual mating flange, gasket, and piping details. The listed thickness and weight support preliminary layout, material handling, and drawing review.
The bolt information is especially important when preparing a flange assembly or checking a CAD model. Confirm the specified stud-bolt designation, length, number of bolts, and hole diameter against the project bolting specification and the mating component. A correct flange selection still requires review of material compatibility, gasket selection, tightening procedure, and pressure-temperature limits.
Using the CAD File in a Piping Layout
The downloadable DWG can support drafting, equipment connection studies, spool detailing, and coordination with adjacent piping. Before using it for fabrication, verify units, insertion point, layer conventions, orientation, and the relationship between the flange face and the connected component. CAD geometry should be checked against the dimension list and the project’s approved design documents.
Related Reference Opportunities
- Link to the site’s Class 600 blind flange size index for comparison with other nominal sizes.
- Link to related flange dimensions and bolt pattern references when checking a mating connection.
- Link to the piping terminology guide for explanations of NPS, DN, flange faces, gaskets, and bolting.
- Link to the CAD and DWG resources section for drafting workflow guidance.
Use the source values as the local reference for this page, and confirm the latest project requirements before procurement, fabrication, or installation.
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 is commonly used for isolation, maintenance, blanking, and future connection work.
Does a blind flange have a center bore?
No. A blind flange is a solid flange without a center bore. Its purpose is to seal the opening at a flanged connection.
What bolt information is listed for this flange?
The reference lists the stud-bolt designation and length, the number of bolts, and the hole diameter. Confirm these details with the mating flange and the approved project bolting specification before assembly.
Can the DWG file be used directly for fabrication?
The DWG is intended to support drafting, detailing, and piping layout coordination. It should be checked against the listed dimensions, project units, approved drawings, material requirements, gasket details, and fabrication procedures before release.
What should be confirmed before installation?
Confirm the flange material, gasket type, bolt requirements, mating connection, and applicable pressure-temperature rating. The project engineer or responsible design authority should verify the complete connection.