Spectacle Blind Flange

What is Spectacle Blind Flange

A Spectacle Blind Flange, also called Spectacle Blind, Figure-8 Blind, or Line Blind, is a special flange accessory used to isolate pipeline flow.

It consists of two connected discs: one solid blind disc for blocking the pipeline and one open ring disc for allowing flow. When the solid side is positioned between two flanges, the pipeline is closed. When the open side is positioned between the flanges, the pipeline remains open.

Spectacle blind flanges are commonly used where pipeline systems require positive isolation for maintenance, safety inspection, pressure testing, or process shutdown.

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Spectacle Blind Flange Specifications

Additional Specifications:

• Type: Spectacle blind, figure-8 blind, line blind
• Structure: One blind plate + one spacer ring connected by bridge
• Face Type: Raised face, flat face, ring joint face, customized sealing face
• Installation: Installed between two standard pipe flanges
• Custom Service: Special OD, ID, thickness, handle design, marking, coating available

Spectacle Blind Flange Materials & Grades

Spectacle blind flanges can be supplied in different materials according to working pressure, temperature, pipeline medium, corrosion environment, and project standard.

Carbon steel spectacle blinds are widely used in oil and gas, refinery, power generation, and general industrial pipelines. Stainless steel spectacle blinds are suitable for chemical processing, marine systems, and corrosive media. Alloy steel and duplex steel materials are available for high-pressure, high-temperature, or special service conditions.

Spectacle Blind Flange Dimensions

Spectacle Blind Flange Dimension Drawing

Spectacle blind flanges can be manufactured according to ASME B16.48 standard dimensions or customer drawings. Key dimensions include outside diameter, inside diameter, thickness, bolt circle diameter, bolt hole diameter, sealing face, and bridge width.

Advantages of Spectacle Blind Flange

Positive Pipeline Isolation

The solid blind side provides complete shutoff for maintenance, inspection, pressure testing, or process shutdown.

Clear Open / Closed Status

The figure-8 design makes it easy to visually identify whether the pipeline is open or closed.

Reliable Sealing Performance

Accurate machining and proper sealing face treatment help reduce leakage risk between flanged joints.

Easy Operation

The spectacle blind can be rotated between the open ring side and blind side after loosening flange bolts.

Multiple Standard Options

Products can be manufactured according to ASME B16.48, ASME B16.5, ASME B16.47, EN, DIN, JIS, and custom drawings.

Wide Material Selection

Carbon steel, stainless steel, alloy steel, duplex steel, nickel alloy, and special materials are available.

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Applications

Oil and Gas Pipelines

Used for isolation in crude oil, natural gas, refinery, and offshore pipeline systems.

Petrochemical Plants

Suitable for process line isolation during maintenance, shutdown, and safety inspection.

Chemical Processing

Stainless steel and alloy spectacle blinds are used for corrosive and hazardous chemical media.

Power Generation

Applied in steam, cooling water, fuel gas, and auxiliary pipeline systems.

Refinery Systems

Used in high-pressure and high-temperature pipeline sections requiring safe flow isolation.

Marine and Shipbuilding

Suitable for ship pipeline systems, fuel lines, seawater lines, and process piping.

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Why Choose Us

Comprehensive Manufacturing Capability

We coordinate cutting, forging, heat treatment, machining, drilling, surface treatment, inspection, and packaging under one production system.

International Standards Compliance

Our products meet ASME B16.48, ASME B16.5, ASME B16.47, EN, DIN, JIS, and customer drawing requirements.

Customized Production Support

We can manufacture spectacle blind flanges with customized thickness, OD, ID, bolt holes, sealing face, bridge width, and material.

Strict Quality Inspection

Each batch is inspected for material grade, dimensions, thickness, bolt hole accuracy, surface finish, sealing face, and appearance.

Wide Material Options

Carbon steel, stainless steel, alloy steel, duplex steel, nickel alloy, and customized materials are available.

Export Packaging Support

Anti-rust treatment, wooden case packaging, steel frame packaging, and customized marking are available for international shipment.

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FAQ

Q: What is a Spectacle Blind Flange?

A: A spectacle blind flange is a figure-8 shaped pipeline isolation component with one solid blind side and one open ring side.

Q: What is the difference between Spectacle Blind and Blind Flange?

A: A blind flange is a separate solid flange used to close a pipe end, while a spectacle blind is installed between two flanges and can switch between open and closed positions.

Q: What standard is commonly used?

A: ASME B16.48 is commonly used for spectacle blinds. ASME B16.5, ASME B16.47, EN, DIN, JIS, and custom drawings can also be supplied.

Q: Can Spectacle Blind Flange be customized?

A: Yes. OD, ID, thickness, bolt holes, sealing face, bridge width, material, coating, and marking can be customized.

Q: Where are Spectacle Blind Flanges commonly used?

A: They are commonly used in oil and gas, petrochemical, chemical processing, refinery, power generation, marine, and industrial pipeline systems.

Contact Us

Ready to enhance your pipeline safety with premium Spectacle Blind Flange solutions? Contact kevin.zhao@hkflange.com for technical specifications and competitive quotations today.

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