This reference provides the key dimensional and connection details for a Blind Flange 4 Inch Class 300, along with practical guidance for interpreting the listed data. Use the source values when checking drawings, selecting mating components, or coordinating piping fabrication.
The flange is a solid closure component, so its dimensions should be reviewed together with the mating flange, gasket, bolting, material specification, and project pressure-temperature requirements.
Blind Flange 4″ Class 300
Blind Flange 4″ Class 300 is used to seal the end of a piping system or close off a flange connection in Class 300 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 4″ Class 300 Dimensions
- Reference Standard: ANSI / ASME B16.5
- Nominal Pipe Size (NPS): 4″
- DN Size: DN100
- Flange Thickness: 30.2mm
- Weight: 12.3kg
- Stud Bolt Size: 3/4″ UNC (or M20) x 115 Long
- Number of Bolts: 8
- Hole Diameter: 7/8″ (22.225mm)
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 4″ Class 300 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 4″ Class 300, which can be used for drafting, detailing, and piping layout coordination.
Available Blind Flange Class 300 Sizes
This size is part of the Blind Flange Class 300 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
The listed NPS and DN values identify the nominal pipe size using two commonly used designation systems. These labels support communication between piping, procurement, fabrication, and drafting teams; they should not be treated as a direct substitute for checking the applicable flange geometry.
Understanding the Connection Details
The flange thickness, bolt-hole diameter, bolt count, and stud-bolt designation are connection details used when coordinating the blind flange with its mating component. Confirm that the bolt arrangement, gasket selection, facing details, and available engagement are compatible with the complete assembly. Bolt length should be verified against the actual flange, gasket, washer, and nut arrangement rather than selected from the flange designation alone.
Why the Class Designation Matters
A Class designation is not, by itself, a universal working-pressure value. Allowable service conditions depend on factors such as material, temperature, fluid service, gasketed joint design, and the governing project requirements. Use the cited flange standard and the approved engineering specification when making a final selection.
Using the CAD Drawing
The downloadable DWG can support drafting, layout coordination, and preliminary detailing. Before issuing a drawing for fabrication, compare the CAD geometry with the authoritative dimension list and confirm that the selected flange facing, material, gasket, and bolting requirements match the project.
Related PipeSTD References
For broader piping coordination, connect this page to related flange dimensions, pipe schedules, flange terminology, and CAD/DWG reference resources. These links help readers move from a single component detail to the surrounding pipe and flange system without treating one component page as a complete design basis.
Frequently Asked Questions
What is a blind flange used for?
A blind flange closes a piping, equipment, or vessel connection where no open flow passage is required. It can also provide an accessible closure point for isolation, maintenance, inspection, or a planned future connection.
Does a blind flange have a center bore?
No. A blind flange is a solid flange without a center bore. The mating face, gasket, and bolting arrangement still need to be checked as part of the complete joint.
Can the listed bolt size be used without further checking?
The listed bolt information is a reference for this flange entry. Confirm the final bolt length and assembly arrangement against the mating flange, gasket, washers, nuts, material requirements, and project specifications.
Is the CAD file sufficient for fabrication?
The DWG is useful for drafting and coordination, but it should not replace verification against the authoritative dimension data, applicable standard, approved material specification, and project requirements before fabrication.
Does Class 300 identify the allowable pressure in every application?
No. The applicable pressure-temperature limit depends on the flange material, service conditions, and governing requirements. Engineering verification is required before installation or operation.