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Spectacle Blind Flanges

Preventing accidental flow and enabling safe maintenance starts with the right line isolation device. Our Spectacle Blind Flanges offer mechanical shutoff without disassembly, reducing hazards during pipeline service.

Standard Specification

ASME B16.48, MSS SP-53, API 590

Pressure Rating

Class 150 to 2500 (PN10 to PN420) [Matches mating flange]

Material

Carbon Steel (A105), Stainless Steel (A182 F304/F316), Alloy Steel (A694 F52)

Nominal Size

½” to 60″ (DN15 to DN1500) [Max 24″ for manual handling]

Flange Type

Spectacle Blind (Spade + Ring spacer integrated)
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Product Description

These integrated figure-8 flanges combine a solid spade and open ring, allowing fast switching between flow and block positions. We follow ASME B16.48 and MSS SP-53 dimensions to ensure seamless fit with mating flanges across global process plants.

Facing Type

Matches mating flange (RF, FF, or RTJ) [Both sides identical]

Dimensions

Thickness per ASME B16.5 + Spade thickness (typically 1.5×flange thickness)

Bolt Circle Diameter

Matches mating flange (ASME B16.5/EN 1092-1) [±0.5mm tolerance]

Number & Size of Bolt Holes

Matches mating flange [Holes aligned for 360° rotation]

Surface Finish

125-250 μin RA (RF), 63-125 μin RA (RTJ) [Both faces identical]

Corrosion Resistance

Material-matched to mating flange [SS316 common for chemical service]

Temperature Rating

-29°C to +538°C (material-dependent) [Same as mating flange]

Material Certification

MTR, EN 10204 3.1, NACE MR0175 (if required)

Gasket Compatibility

Matches mating flange gasket [Often supplied with captive gasket]

Coating/Plating

HDG, Xylan, or material-matched [No coating on sealing surfaces]

Manufacturing Method

Plasma-cut from plate (A516) or forged (A105) + CNC machining [One-piece construction]

Technical Advantages

Standard blind flanges require full removal, but our figure-8 design only needs 180-degree rotation, saving downtime during isolation. Each unit maintains identical facing on both sides to avoid sealing mismatch when switching between spade and ring. 
 
CNC-machined from forgings or A516 plates, these spectacle blind flanges meet ±0.5mm bolt hole and bolt circle tolerances for tight alignment. Surface roughness between 125–250 μin RA (RF) and 63–125 μin RA (RTJ) supports leak-free sealing under repeated thermal cycles.

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Industry Applications

Petrochemical Processing Units

Handles pressure classes up to 2500 with reliable sealing in pipelines carrying aromatic hydrocarbons and high-temperature steam. 

Natural Gas Compressor Stations

Allows safe isolation of compressors and valves during pigging or maintenance, avoiding pressure surges or hazardous leaks. 

Refinery Heat Exchanger Systems

Used between tube bundle and header connections to simplify shutdowns without disturbing heavy flange assemblies. 

Offshore Oil Rigs

Corrosion-resistant SS316 or A694 F52 builds withstand salt-laden environments while enabling tool-free line segregation. 

Nuclear Power Cooling Loops

Ensures operational safety in secondary loop systems using RTJ facings and certified forged A105 material. 

Water Desalination Plants

Simplifies process section shutdowns during membrane flushing or chemical dosing with spade-to-ring rotation access. 

Spectacle Blind Flanges

Performance Aligned with Process Demands

These spectacle blinds reduce the risk of misaligned gaskets or bolt preload loss during frequent isolations. Matching bolt patterns and thickness ensure exact fit with ASME B16.5 or EN 1092-1 flanges, removing trial-fit errors. 
 
They support pressure ratings up to Class 2500 while withstanding temperatures from -29°C to +538°C without deformation. For documentation needs, we provide MTRs, EN 10204 3.1, and NACE MR0175 compliance for all material grades upon request. 

Spectacle Blind Flanges

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Having Doubts? Our FAQ

Check all our Frequently Asked Question

Can Spectacle Blind Flanges be reused during line maintenance?

Yes, they are reusable if surface finish and dimensional tolerance remain within mating limits. Visual inspection and gasket seating check help confirm usability. Reuse reduces downtime and consumable costs in scheduled shutdowns.

Does the spade thickness affect pressure integrity or bolting torque

Spade thickness is calculated as 1.5 times the flange thickness to maintain load distribution. This prevents gasket blowout and ensures uniform bolt torque during flange makeup. Always match this with the original flange class.

How do we ensure gasket compatibility with Spectacle Blind Flanges?

Gasket face matches the mating flanges of RF, FF, or RTJ on both sides of the spectacle. The flange accepts standard spiral wound or ring-type gaskets. This prevents seal mismatch and field-fit issues.

Does surface finish variation affect sealing performance on these flanges?

Yes, surface finish directly impacts gasket seating and long-term leak prevention. We maintain 125–250 μin RA for RF and 63–125 μin RA for RTJ as per ASME norms. Both sides of the flange are finished identically to avoid sealing imbalance.

Can Frigate customize the handle for confined space operations?

Yes, we can reduce the spade handle size or shift its orientation for access clearance. This modification maintains balance during rotation and avoids interference with nearby fittings. Custom requests require prior layout confirmation.

Can Frigate support bulk orders with consistent dimensional accuracy across batches?
  • Yes, Frigate ensures batch-to-batch consistency through CNC-controlled machining and calibrated inspection systems 
  • We maintain strict tolerance control (±0.5 mm) across high-volume production runs 
  • Each batch is traceable with heat numbers and inspection records for quality assurance 
  • Suitable for EPC contractors and large-scale plant shutdown requirements 
What lead times can Frigate offer for urgent shutdown or turnaround requirements?
  • Standard sizes are available with expedited production timelines 
  • Priority manufacturing slots are allocated for shutdown-critical orders 
  • In-house machining and forging partnerships reduce dependency delays 
  • Logistics support ensures timely dispatch aligned with project schedules 
Does Frigate provide documentation packages required for project approvals?
  • Complete documentation including MTRs, EN 10204 3.1, and compliance certificates is provided 
  • NACE MR0175 and PMI reports can be included upon request 
  • Dimensional inspection reports and surface finish records are available 
  • Documentation is aligned with EPC, consultant, and end-user approval formats 
Can Frigate supply spectacle blinds matched to existing plant flange standards?
  • Yes, we manufacture fully compatible units as per ASME B16.5, B16.48, and EN 1092-1 
  • Reverse engineering support is available for legacy or non-standard flanges 
  • Exact bolt pattern, thickness, and facing match eliminate site modification issues 
  • Ensures direct installation without trial fitting or rework 
What value does Frigate bring compared to traders or non-manufacturing suppliers?
  • Direct manufacturer advantage ensures better control over quality, cost, and delivery 
  • Engineering support from design to final inspection reduces procurement risk 
  • Customization flexibility for materials, coatings, and geometry requirements 
  • Reliable production backed by proven industrial supply experience 
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LOCATIONS

Registered Office

10-A, First Floor, V.V Complex, Prakash Nagar, Thiruverumbur, Trichy-620013, Tamil Nadu, India.

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9/1, Poonthottam Nagar, Ramanandha Nagar, Saravanampatti, Coimbatore-641035, Tamil Nadu, India. ã…¤

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LOCATIONS

Registered Office

10-A, First Floor, V.V Complex, Prakash Nagar, Thiruverumbur, Trichy-620013, Tamil Nadu, India.

Other Locations

  • Bangalore
  • Chennai
  • Coimbatore
  • Germany
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Spectacle Blind Flanges

Spectacle Blind Flanges

Need reliable wires and cables for your next project? Get in touch with us today, and we’ll help you find exactly what you need!

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Spectacle Blind Flanges

Spectacle Blind Flanges

Need reliable Machining for your next project? Get in touch with us today, and we’ll help you find exactly what you need!

Get Latest Price

Get Price Form