This reference page provides the dimensional and installation-planning information for an 18 inch Class 600 blind flange. Use the source data below to check the nominal size, DN designation, flange thickness, weight, bolt arrangement, and hole diameter before preparing piping drawings or procurement documents.
A blind flange has no center opening. It closes a flanged connection while retaining a bolted arrangement that can be opened for inspection, maintenance, equipment isolation, or a future piping change. For coordinated design work, compare this page with the project’s flange dimensions, piping classes, gasket selection, and CAD/DWG reference requirements.
Blind Flange 18″ Class 600
Blind Flange 18″ Class 600 is used to seal the end of a piping system or close off a flange connection in Class 600 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 600 Dimensions
- Reference Standard: ANSI / ASME B16.5
- Nominal Pipe Size (NPS): 18″
- DN Size: DN450
- Flange Thickness: 82.6mm
- Weight: 286kg
- Stud Bolt Size: 1 5/8″ UNC (or M42) x 275 Long
- Number of Bolts: 20
- Hole Diameter: 1 3/4″ (44.45mm)
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 600 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 600, which can be used for drafting, detailing, and piping layout coordination.
Available Blind Flange Class 600 Sizes
This size is part of the Blind Flange Class 600 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 Reference Data
The listed NPS and DN designations identify the nominal pipe size in two commonly used sizing systems. They are reference designations rather than a substitute for checking the complete flange geometry and the mating components used on the project.
The flange thickness and weight are useful for detailing, handling planning, support coordination, and shipping or procurement review. Weight should not be used alone to determine lifting equipment, support requirements, or allowable loads; those decisions require project-specific engineering and verified material information.
The bolt entry identifies the stud bolt size, thread designation, length, and bolt count shown for this flange. The hole diameter is a separate flange dimension: it describes the opening through the flange for the fasteners and should not be confused with the bolt’s nominal outside dimension. Confirm the complete bolting arrangement, gasket, washers, tightening procedure, and mating flange before fabrication or installation.
Design and Drafting Checks
- Confirm that the blind flange matches the connected flange face, rating, gasket arrangement, and project piping specification.
- Check bolt access and clearance in the piping layout, especially near valves, equipment, structural members, and insulation.
- Use the provided DWG as a drafting reference, then verify the drawing against the approved project standard and current procurement information.
- Review material, corrosion allowance, service conditions, pressure-temperature limits, and inspection requirements with the responsible engineer.
- For a permanent closure or high-consequence service, verify whether additional analysis, testing, or a different closure arrangement is required.
Related Reference Topics
For broader design coordination, link this page to related resources covering blind flange dimensions, Class 600 flange references, stud bolt sizing, gasket selection, pipe schedules, and flange CAD drawings. These references help users compare adjacent sizes and coordinate flange connections without treating one dimension list as a substitute for the project specification.
Frequently Asked Questions
What is an 18 inch Class 600 blind flange used for?
It is used to close a piping end, equipment nozzle, valve connection, or other flanged opening where a solid bolted closure is required. Typical uses include isolation, maintenance shutdown work, and provision for a future connection.
Does a blind flange have a center bore?
No. A blind flange is a solid flange without a center bore. Its purpose is to block the connected opening rather than allow fluid to pass through the flange.
What bolt information is provided for this flange?
The reference data lists the stud bolt size as 1 5/8 inch UNC (or M42) x 275 long, together with a bolt count of 20. Confirm the final bolting specification, length, materials, washers, and tightening requirements before installation.
Is the Class 600 designation the same as a pressure value?
Class 600 is a flange pressure-class designation, not a single universal pressure value for every temperature and material condition. The applicable pressure-temperature rating must be confirmed from the governing standard, material specification, and project requirements.
Can the supplied DWG be used directly for fabrication?
The DWG is intended as a drafting and piping-layout reference. Before fabrication, check it against the approved project drawings, material specification, gasket and bolting requirements, and the governing flange standard.