This reference provides the published dimension data for a Blind Flange 3 1/2 Inch Class 150, including its nominal size, flange thickness, weight, stud bolt details, bolt quantity, and hole diameter. Use the values below as a practical reference when reviewing piping layouts, flange connections, and fabrication information.
The page also explains how to interpret the flange identification and use the associated CAD file. For project work, compare the listed data with the mating flange, gasket specification, material requirements, and current project documentation before procurement or installation.
Blind Flange 3 1/2″ Class 150
Blind Flange 3 1/2″ Class 150 is used to seal the end of a piping system or close off a flange connection in Class 150 service. It is a solid flange without a center bore and is commonly applied in industrial piping, maintenance isolation points, and future line expansion connections.
This dimension data is based on ANSI / ASME B16.5.
Blind Flange 3 1/2″ Class 150 Dimensions
- Reference Standard: ANSI / ASME B16.5
- Nominal Pipe Size (NPS): 3 1/2″
- DN Size: DN90
- Flange Thickness: 22.4mm
- Weight: 5.9kg
- Stud Bolt Size: 5/8″ UNC (or M16) x 90 Long
- Number of Bolts: 8
- Hole Diameter: 3/4″ (19.05mm)
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 150 is commonly used for:
- Pipe end closure
- Equipment isolation
- Valve and nozzle blanking
- Maintenance shutdown work
- Process and utility piping systems
CAD Drawing Download
This page includes the CAD drawing file for Blind Flange 3 1/2″ Class 150, which can be used for drafting, detailing, and piping layout coordination.
Available Blind Flange Class 150 Sizes
This size is part of the Blind Flange Class 150 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
A blind flange has no center bore, so its primary function is to close a flanged connection rather than provide a passage for the pipe. This makes it useful at pipe ends, equipment connections, isolation points, and locations reserved for possible future work.
Understanding the size identification
The NPS and DN entries identify the nominal pipe-size designation used for the flange. They are reference designations, not a replacement for checking the complete flange geometry. When coordinating this component with piping drawings or a related pipe dimensions reference, confirm that the mating components use compatible size and flange classifications.
Checking bolts and connection details
The source data lists the stud bolt designation, length, bolt quantity, and hole diameter. These details should be reviewed together rather than independently. Confirm the mating flange hole pattern, gasket arrangement, available thread engagement, and project bolting requirements before selecting hardware.
Using the CAD download
The downloadable DWG can support drafting, detailing, and piping layout coordination. Treat the CAD file as a design-reference resource and verify that the selected drawing revision matches the dimension data and project requirements. Related flange dimensions, piping fittings, and CAD/DWG reference pages can help with adjacent component checks.
Before fabrication or installation
Confirm the flange material, gasket type, bolt specification, applicable pressure-temperature requirements, and project design basis. A dimension match alone does not establish that a connection is suitable for a particular service; final selection should be checked by the responsible engineering or fabrication team.
Frequently Asked Questions
What is a Blind Flange 3 1/2 Inch Class 150 used for?
It is used to close a piping end or flanged connection. Typical uses listed for this size include pipe end closure, equipment isolation, valve and nozzle blanking, maintenance shutdown work, and process or utility piping systems.
Does a blind flange have a center opening?
No. A blind flange is a solid flange without a center bore. It closes the connection instead of allowing fluid to pass through the flange.
What bolt information is provided for this flange?
The reference lists the stud bolt designation and length, the number of bolts, and the hole diameter. These details should be checked against the mating flange and the project’s bolting and gasket requirements.
Can the DWG file be used for fabrication?
The DWG is intended to support drafting, detailing, and piping layout coordination. Before fabrication, verify the drawing against the published dimension data, project specifications, material requirements, and the latest approved documents.
Is Class 150 alone enough to select the flange?
No. The flange class and dimensions are only part of the selection process. Material, gasket, bolting, service conditions, pressure-temperature requirements, and project standards must also be confirmed.