Figure 8 Spectacle Blinds

At Flowell, our Figure 8 Spectacle Blinds — also known as spectacle flanges or figure-of-eight blinds—are precision-engineered to deliver reliable, secure shutoff capabilities for pipeline systems where frequent maintenance or safety checks are necessary. These devices are critical components in isolating segments of piping, ensuring not just efficiency but also the safety of personnel and integrity of the overall system.

Our Spectacle Blinds are manufactured to meet stringent industry standards and are available in a variety of materials, sizes, and pressure classes. Whether you’re working in petrochemical, oil and gas, chemical processing, or power generation, our figure 8 spectacle blinds offer dependable performance under challenging conditions.

API 590 Compliance for Safety and Reliability

We manufacture our Spectacle Blinds to conform to API 590 standards. This ensures our products maintain the thickness and integrity required to withstand the pressure and temperature ratings associated with ANSI-rated flanges. Meeting API 590 requirements is not just a box we check—it’s a commitment to safety and reliability in every application.

By adhering to these industry-recognized specifications, we offer you the peace of mind that our products can handle extreme operating conditions, resist deformation, and retain their shape and strength over time. This level of precision is essential when dealing with high-pressure systems where failure is not an option.

Materials Readily Available & Material Selection

We maintain a substantial inventory of carbon steel Spectacle Blinds, allowing for the rapid fulfillment of most standard orders. Carbon steel is a popular choice due to its excellent strength, durability, and cost-effectiveness, making it suitable for a wide range of industrial applications.

In addition to carbon steel, we also stock 304 and 316 stainless steel Spectacle Blinds. These materials offer superior corrosion resistance and are ideal for harsh environments, including chemical processing and marine applications. When operating conditions demand even more specialized properties, we’re equipped to provide Spectacle Blinds in alternative materials such as alloy steels, duplex stainless steels, Inconel, Monel, and other high-performance metals. Custom materials are available upon request, and we’re happy to consult with you on spectacle blind material selection for your specific application.

Design and Functionality of Figure 8 Spectacle Blinds

The Figure 8 Spectacle Blind gets its name from its shape—a combination of a solid plate (blank) on one end and an open ring (spacer) on the other, connected by a central bridge. This design allows for easy switching between the pipeline’s open and closed states without the need to fully remove the component from the line.

When the solid side is in place between flanges, the flow is completely shut off, making it ideal for isolating a section of piping for maintenance or emergencies. When the ring side is installed, flow is allowed through the system. This simple yet effective configuration ensures a clear, visible indication of line status, minimizing the risk of errors during operation. Compare spectacle blind vs spacer or difference between spectacle blind and blank flange to understand benefits of this design.

Figure 8 Spectacle Blinds Dimensions & Weight

Accurate dimensions are crucial for a proper fit and seal. Our figure 8 spectacle blind dimensions span standard flange sizes from ½” to 24″ and beyond, with custom fabrication available for larger or non-standard configurations. We also provide approximate weight of figure 8 spectacle blinds via weight charts to aid handling and lifting planning.

Pressure Ratings & Standards

Our Spectacle Blinds are available in multiple pressure classes to suit varied applications. See figure 8 blinds pressure ratings to choose the correct class for your system. We adhere to spectacle blind standards such as ANSI B16.48, ASME, and API requirements, ensuring safety and compatibility with existing flange systems.

• Standard ratings: Class 150, 300, 600, 900, 1500, etc., per ANSI flange pressure classes.
• Custom pressure classes available upon request for specialized applications.
• Each blind is marked with its pressure rating and heat number for traceability.

Installation & Fitting Instructions

Proper installation of spectacle blinds is essential for safe operation. Follow our installation of spectacle blinds and figure 8 blind fitting instructions to ensure a leak-free seal and clear line status indication.

• Preparation: Verify flange faces are clean and undamaged. Confirm correct blind size and pressure rating.
• Orientation: Align the central bridge section so the solid side or ring side can be easily rotated into position.
• Gasket & Spacer Alternatives: For certain operations, consider pipe blind spacer alternatives or use a spacer plate when required.
• Torque Sequence: Apply flange bolts in a cross pattern to the recommended torque per flange class.
• Verification: After installation, perform a pressure test if needed and visually confirm the correct side (solid or ring) is in place.
• Spectacle Blind Code Requirements: Ensure compliance with local or industry code requirements for isolation devices; document installation per regulatory standards.

Applications & Uses

Our applications of figure 8 blinds span many industries requiring reliable isolation. Below are common uses of figure 8 spectacle blinds:

• Oil and Gas Processing: Isolate line segments safely during maintenance or turnaround.
• Chemical Manufacturing: Provide secure shutoff during batch changes or emergency shutdown.
• Power Generation: Safely isolate turbine, boiler, or heat exchanger circuits.
• Petrochemical Plants: Enable verifiable flow stoppage in critical lines.
• Marine & Offshore: Withstand corrosive saltwater environments; allow quick isolation for safety checks.
• Water Treatment & Utilities: Control flow for inspection and maintenance of pump stations or pipe networks.
• Pharmaceutical & Food Processing: When compatible materials selected, permit sanitary isolation in process lines.

Ordering Information & Custom Fabrication

For ordering information for spectacle blinds, contact our sales team with details: required size (nominal diameter), pressure class, material grade, and any special surface finish. We also support custom spectacle blind fabrication for non-standard dimensions, exotic alloys, or unique tolerances.

• Standard stock: Common sizes and materials (carbon steel, 304/316 SS) available for quick delivery.
• Custom requests: Provide detailed specs; our engineers will supply drawings, lead time, and quotes.
• Lead times: Standard items: typically 1–2 weeks. Custom items: per complexity and material availability.
• Documentation: We supply mill certificates, material test reports, and compliance certificates as needed.

Inspection & Maintenance

Regular inspection of spectacle blinds and maintenance of figure 8 blinds help ensure long service life and safety:

• Visual Checks: Inspect for corrosion, cracks, or deformation on both solid and ring sides before installation.
• Dimensional Verification: Confirm critical dimensions (bolt hole pattern, outer diameter) match flange specs.
• Surface Condition: Check finish; re-passivate stainless surfaces if needed; touch up coatings to prevent corrosion.
• Storage: Store blinds flat in a clean, dry environment to avoid warping; tag with size and rating for easy identification.
• Replacement Schedule: Replace or refurbish after repeated use in abrasive or high-temperature services per your maintenance plan.

Surface Finish and Identification

Each Spectacle Blind is clearly marked with essential information, including material grade, pressure rating, heat number, and size. This makes traceability easy and aligns with ISO 9001 quality assurance systems.

Surface finishes are tailored to your needs—standard mill finishes are common, but we also offer sandblasted, pickled, passivated, and coated options depending on your requirements for cleanliness, corrosion resistance, or aesthetic uniformity.

Why Choose Flowell For Figure 8 Spectacle Blinds?

When you partner with Flowell, you’re not just buying a component—you gain decades of technical expertise, responsive customer service, and a supply chain built for reliability. We’re committed to delivering high-performance pipeline components that meet or exceed your expectations.

• In-Stock Availability: Fast delivery on commonly used materials like carbon steel and stainless steel spectacle blinds.
• Expert Consultation: Guidance on material selection, design, and compliance with spectacle blind code requirements.
• Custom Capabilities: Tailored solutions for non-standard systems and custom spectacle blind fabrication.
• Uncompromising Quality: Every blind is manufactured to the highest industry standards.
• Dedicated Support: Our team assists from inquiry through installation and maintenance.

Request a Quote or Consultation

Whether you’re placing a bulk order or sourcing a single custom unit, we’re ready to help. Reach out to us today for a quote, consultation, or technical specification support. Our knowledgeable team can guide you through the selection process to ensure you get the right spectacle blind for your project.

At Flowell, we don’t just deliver parts—we deliver confidence.

Figure 8 Spectacle Blinds FAQs