This reference provides the source dimensions and drafting information for a Blind Flange 18 Inch Class 400. Use the listed flange thickness, weight, stud bolt details, bolt count, and hole diameter when checking a piping layout, fabrication drawing, or procurement specification.
Because a blind flange has no center bore, it closes a flanged connection rather than passing pipe through the flange. The data on this page should be read together with the applicable project specification, gasket requirements, material requirements, and pressure-temperature limitations.
Blind Flange 18″ Class 400
Blind Flange 18″ 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 18″ Class 400 Dimensions
- Reference Standard: ANSI / ASME B16.5
- Nominal Pipe Size (NPS): 18″
- DN Size: DN450
- Flange Thickness: 66.5mm
- Weight: 207kg
- Stud Bolt Size: 1 3/8″ UNC (or M36) x 230 Long
- Number of Bolts: 24
- 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 18″ 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 18″ 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 the Blind Flange Reference
The nominal pipe size identifies the associated piping size, while the DN designation provides the metric size reference shown in the source data. These labels help keep piping drawings, equipment connection schedules, and purchasing documents aligned.
Flange thickness and weight are useful for design coordination, handling planning, support reviews, and checking the physical envelope of a connection. The weight listed on this page is for the flange reference itself; connected components, bolts, gaskets, and temporary handling equipment should be considered separately where relevant.
Bolt and Hole Information
The stud bolt entry identifies the specified inch and metric bolt-size references together with the stated bolt length. The bolt count and hole diameter should be checked against the mating flange, gasket arrangement, and project bolting specification before fabrication or installation. Do not assume that a bolt reference alone confirms tightening procedure, material compatibility, or joint suitability.
Using the CAD File
The downloadable DWG can support piping layout, equipment coordination, detailing, and preliminary interference checks. Before issuing a drawing for fabrication, compare the CAD geometry with the authoritative dimension data and confirm the required facing, gasket, material, and connection details.
Related Pipe and Flange References
For broader design and drafting work, connect this reference with the site’s blind flange dimensions, flange bolt charts, pipe schedules, flange terminology, and CAD/DWG downloads. Reviewing adjacent Class 400 sizes can also help when coordinating a piping system with more than one nominal size.
Installation and Procurement Checks
- Confirm the mating flange standard and facing arrangement.
- Verify gasket type, material specification, and project requirements.
- Check that the specified bolts provide the required fit and engagement for the joint.
- Review pressure-temperature requirements with the responsible engineer.
- Confirm the latest approved drawing and applicable standard before fabrication.
Blind Flange 18 Inch Class 400 FAQ
What is a blind flange used for?
A blind flange closes the end of a pipe, vessel nozzle, valve connection, or other flanged opening. It can support isolation, maintenance work, equipment blanking, and future connection planning.
Does a blind flange have a center bore?
No. A blind flange is a solid flange without a center bore, so it blocks the connected opening when installed with the appropriate gasket and bolting arrangement.
What bolt information is listed for this flange?
The source data lists the stud bolt size as 1 3/8 inch UNC, or M36, with the stated length, along with the number of bolts and hole diameter. These details should be checked against the mating flange and project bolting requirements.
Can the DWG be used directly for fabrication?
The DWG is intended to support drafting, detailing, and piping coordination. Fabrication should proceed only after the drawing, material, facing, gasket, bolting, and project requirements have been reviewed and approved.
What should be verified before installation?
Confirm the mating connection, gasket, flange material, bolt specification, pressure-temperature requirements, and current approved project documents before installation.