This reference page explains the listed dimensions and identification details for a Blind Flange 12 Inch Class 900. Use it alongside related flange dimension pages, piping terminology resources, and CAD/DWG references when checking a piping layout or preparing fabrication documentation.
The source data provides the nominal size, DN designation, flange thickness, weight, stud bolt details, bolt quantity, and hole diameter. Treat those values as the controlling reference for this page, then verify the project specification before ordering, fabricating, or installing the flange.
Blind Flange 12″ Class 900
Blind Flange 12″ 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 12″ Class 900 Dimensions
- Reference Standard: ANSI / ASME B16.5
- Nominal Pipe Size (NPS): 12″
- DN Size: DN300
- Flange Thickness: 79.2mm
- Weight: 189kg
- Stud Bolt Size: 1 3/8″ UNC (or M36) x 255 Long
- Number of Bolts: 20
- Hole Diameter: 1 1/2″ (38.1mm)
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 12″ 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 12″ 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 Read the Blind Flange Reference
A blind flange has no center bore. Unlike a flange intended to connect directly to an open pipe bore, it closes a piping end, nozzle, or flanged connection. The solid face can support isolation, maintenance planning, or a future connection, but the complete assembly still depends on the selected gasket, bolting, facing, material, and project requirements.
NPS and DN Identification
The page identifies the flange as NPS 12 and DN300. NPS and DN are nominal designations rather than a direct statement of every physical dimension. For fabrication or drafting, use the listed flange dimensions and the supplied CAD file instead of estimating geometry from the nominal size.
Bolting and Hole Information
The listed stud bolt size, length, bolt count, and hole diameter describe the bolted connection reference provided for this flange. Confirm compatibility with the mating flange, gasket, washers, threading practice, and assembly procedure. Bolt length should not be selected from nominal size alone because the final requirement can depend on the complete joint stack-up.
Using the CAD File
The downloadable DWG can support piping layout, detailing, and coordination. Before using it for fabrication, compare the drawing with the page data and the project specification. Keep flange orientation, gasket seating, bolt access, and maintenance clearance coordinated with adjacent valves, fittings, equipment, and pipe supports.
Related Reference Topics
- Compare this page with other Class 900 blind flange sizes when selecting a matching connection.
- Use related flange dimension references to check mating components and connection terminology.
- Review the site’s CAD/DWG piping resources for drafting and layout coordination.
- Check applicable material, gasket, bolting, and pressure-temperature requirements before engineering approval.
Frequently Asked Questions
What is a blind flange used for?
A blind flange closes a pipe end, vessel nozzle, valve connection, or other flanged opening. It can provide an isolation point and allow later access or extension, subject to the project design and operating requirements.
What does Class 900 identify?
Class 900 identifies the flange pressure class designation used by the referenced flange standard. It should not be treated as a standalone approval for every service condition; the applicable pressure-temperature rating, material, gasket, bolting, and design requirements must be verified.
Are NPS 12 and DN300 interchangeable descriptions?
They are the nominal size designations shown for this reference. They help identify the flange size, but they do not replace the detailed dimensions needed for fabrication, procurement, or mating-component checks.
Can the DWG file be used directly for fabrication?
The DWG is intended to assist drafting, detailing, and piping layout coordination. Confirm its geometry and the listed page data against the project specification and approved fabrication documents before release.
What should be checked before installation?
Confirm the mating flange, facing, gasket, material specification, stud bolts, bolt length, assembly method, alignment, and applicable pressure-temperature requirements. Installation should follow the responsible engineer’s approved procedure.