This reference provides the source dimensions and installation-related details for a Blind Flange 12 Inch Class 400. Use the data to coordinate piping layouts, flange connections, maintenance isolation points, and CAD details.
A blind flange has no center opening, so its primary function is to close a flanged connection rather than provide a passage for fluid. Before using the listed dimensions for fabrication or procurement, compare them with the project flange specification, gasket arrangement, bolting requirements, and service conditions.
Blind Flange 12″ Class 400
Blind Flange 12″ 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 12″ Class 400 Dimensions
- Reference Standard: ANSI / ASME B16.5
- Nominal Pipe Size (NPS): 12″
- DN Size: DN300
- Flange Thickness: 57.2mm
- Weight: 102kg
- Stud Bolt Size: 1 1/4″ UNC (or M33) x 205 Long
- Number of Bolts: 16
- Hole Diameter: 1 3/8″ (34.925mm)
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 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 12″ 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 This Blind Flange Reference
The source data identifies the flange as NPS 12, with the corresponding DN designation, flange thickness, listed weight, stud bolt information, bolt quantity, and hole diameter. These values should be read together when checking a drawing or coordinating the flange with adjacent piping and equipment.
Connection and Bolting Considerations
The bolt quantity, stud size, bolt length, and hole diameter are connection details that affect flange assembly and detailing. Confirm that the selected studs, nuts, washers where required, gasket, and tightening procedure match the governing project requirements. Bolt length should also be checked against the actual flange, gasket, and facing arrangement rather than assumed from nominal pipe size alone.
Use in Layouts and Maintenance Planning
Because the flange closes a connection without a center bore, it can be shown at a pipe end, nozzle, valve connection, or other flanged isolation point. In a layout, consider access for bolting, gasket replacement, inspection, and future removal. The listed weight is useful for handling and support coordination, but lifting and temporary-support decisions require project-specific engineering review.
CAD and Related Reference Work
The downloadable DWG can support drafting, equipment arrangement, piping layout, and detail coordination. Check the drawing against the authoritative dimension list before issuing fabrication documents. Related internal references may include flange terminology, pipe schedules, gasket selection, stud bolt terminology, and other blind flange size pages.
Important Design Check
Class designation alone does not replace a pressure-temperature review. Confirm the flange material, facing, gasket, bolt specification, fluid service, design conditions, and applicable project or governing standard requirements before approval for service.
Frequently Asked Questions
What is a 12-inch Class 400 blind flange used for?
It is used to close a flanged piping, vessel, equipment, or nozzle connection. Typical uses include line-end closure, isolation, maintenance work, and connections reserved for future modification.
Does a blind flange have a center bore?
No. A blind flange is a solid flange without a center bore, allowing it to block the connected opening when correctly gasketed and bolted.
What nominal and DN sizes are listed?
The source identifies the flange as NPS 12 and DN300. Use both designations when comparing drawings, procurement documents, and related reference pages.
How many bolts are listed for this flange?
The source lists 16 bolts. Confirm the bolt arrangement and hardware against the project specification and the mating flange before installation.
Is the listed stud bolt length automatically suitable?
No. The listed stud bolt information is a reference for this flange entry, but final suitability depends on the mating flange, gasket, washers, nuts, facing, and required thread engagement.
Can the CAD file be used directly for fabrication?
The DWG is intended to support drafting and coordination. Verify its geometry and the applicable project requirements against the source dimensions before using it for fabrication or issued-for-construction documentation.