ASME B16.48 Spectacle Blind Flange Manufacturer & Exporter in Mumbai, India
Amardeep Steel manufactures and exports Spectacle Blind Flanges to ASME B16.48, ASME B16.5, MSS SP-44 and API standards, in sizes from ½" to 48" NB and pressure classes 150# through 2500#. As an ISO-certified manufacturer based in Mumbai, we produce spectacle blinds also called Figure-8 Blanks, Spade and Spacer Flanges in Carbon Steel, Stainless Steel, Alloy Steel, Duplex Steel, Super Duplex Steel, Nickel Alloys, Inconel, Hastelloy and Monel. Every flange is supplied with EN 10204 3.1 mill test certificates and tested per ASME B16.48 dimensional tolerances before dispatch.
What Are Spectacle Blind Flanges?
A Spectacle Blind Flange also referred to as a Figure-8 Blank, Paddle Blank, or Spade and Spacer is a dual-function line-isolation device governed by ASME B16.48. Its figure-eight profile combines one solid blank disc (the 'blind') for complete flow shut-off and one open ring (the 'spacer' or 'ring spacer') for full flow passage. Operators rotate the flange 180 degrees between states without dismantling the piping system, giving immediate visual confirmation of isolation status, a critical safety requirement in oil & gas, petrochemical and power generation service.
Spectacle Blind vs Paddle Blind vs Spade Blind
Use this quick-reference table to identify the correct isolation device for your piping requirement:
| Type | Construction | Use Case | Standard |
|---|---|---|---|
| Spectacle Blind | Figure-8 — blind disc and spacer ring permanently joined by a web | Long-term installations requiring frequent switching between open/closed; positive visual indication of status | ASME B16.48 |
| Paddle Blind (Spade) | Solid disc only — separate from spacer | Single-purpose isolation; used with a separate spacer ring when space allows | ASME B16.48 |
| Spacer Ring | Open ring — no blind disc | Maintains bolt spacing when the blind is removed; used as a pair with the paddle blind | ASME B16.48 |
Key Features & Benefits
- Visual Flow Indication: Immediate confirmation of open or closed status — no need to open the piping system.
- Quick Isolation: Rotate 180° between flow and no-flow positions without system disassembly.
- Safety Enhancement: Positive shut-off for maintenance operations; visual status prevents accidental start-up.
- Cost-Effective: One component replaces a separate blind flange and spacer ring.
- Compliance: Dimensionally inspected per ASME B16.48; mating flange faces conform to ASME B16.5.
Spectacle Blind Flanges Specifications
Amardeep Steel manufactures spectacle blind flanges to the specifications below, covering the full commercial size and pressure-class range. Contact us for non-standard dimensions or custom material grades.
| Product Name | Spectacle Blind Flanges / Figure-8 Blanks / Spade and Spacer Flanges |
|---|---|
| Size Range | ½" (15 NB) to 48" (1200 NB) |
| Pressure Class | 150#, 300#, 600#, 900#, 1500#, 2500# | PN6, PN10, PN16, PN25, PN40, PN64 |
| Standards | ASME B16.48, ANSI B16.5, ANSI B16.47 (Series A & B), MSS SP-44, API-605, AWWA, Custom Drawings |
| Face Type | Raised Face (RF), Flat Face (FF), Ring Type Joint (RTJ) |
| Coating | Anti-rust Paint, Oil Black Paint, Yellow Transparent, Zinc Plated, Hot Dip Galvanized |
| Test Certificates | EN 10204 3.1, Raw Material Certificates, 100% Radiography Test Report, Third Party Inspection |
Spectacle Blind Flanges Materials & Grades
Carbon Steel Spectacle Blind Flanges
Standards: ASTM A105, ASTM A350 LF1/LF2/LF3, ASTM A694 F42/F46/F52/F60/F65/F70, A516 Gr.60/65/70
- High-temperature service: ASTM A105 (up to 650°F)
- Low-temperature service: ASTM A350 LF2 (down to -50°F) — suitable for LNG, cryogenic and sub-zero process applications. Notch toughness tested to ASME B16.48 requirements.
Stainless Steel Spectacle Blind Flanges
Standards: ASTM A182, ASTM A240 | Grades: F304, F304L, F304H, F316, F316L, F316Ti, F316H, F316LN, F310, F310H, F317, F317L, F321, F321H, F347, F347H, F201, F202, F904L
Alloy Steel Spectacle Blind Flanges
Standards: ASTM A182, ASTM A387 | Grades: F1, F5, F9, F11, F12, F22, F91
Duplex & Super Duplex Steel Spectacle Blind Flanges
Standards: ASTM A182, ASTM A240 | Grades: UNS S31803 (2205), UNS S32205, UNS S32750 (2507), UNS S32950
For seawater and chloride-rich environments, Duplex S31803 or Super Duplex S32750 are specified — both deliver PREN > 35 for chloride stress corrosion resistance. For high-temperature offshore service, Inconel 625 or Hastelloy C276 are standard choices.
Nickel Alloy Spectacle Blind Flanges
Standards: ASTM B564, SB160, SB162, SB472 | Grades: Nickel 200 (N02200), Nickel 201 (N02201), Monel 400 (N04400), Monel 500 (N05500), Inconel 600 (N06600), Inconel 625 (N06625), Inconel 601 (N06601), Inconel 800 (N08800), Inconel 825 (N08825), Hastelloy C276 (N10276), Alloy 20 (N08020)
Copper Alloy Spectacle Blind Flanges
Standards: ASTM SB61, SB62, SB151, SB152 | Grades: C10100, C10200, C10300, C70600 (Cu-Ni 90/10), C71500 (Cu-Ni 70/30)
ASME B16.48 Spectacle Blind Flanges Dimensions
Detailed spectacle blind flange dimensions as per ASME B16.48 standard. All dimensions in millimetres (mm) unless otherwise noted.
Class 150 Spectacle Blind Flange Dimensions (ASME B16.48)
Class 150 spectacle blind flanges are the standard choice for low-pressure utility and process lines. All dimensions per ASME B16.48.
| NPS | Outside Ø (A) (mm) | Inside Ø (B) (mm) | Centerline (C) (mm) | Thickness (t) (mm) | Web Width (W) (mm) |
|---|---|---|---|---|---|
| 1/2 | 45 | 16 | 60 | 3.0 | 38 |
| 3/4 | 54 | 21 | 70 | 3.0 | 38 |
| 1 | 64 | 27 | 80 | 3.0 | 38 |
| 1¼ | 73 | 42 | 90 | 6.4 | 38 |
| 1½ | 83 | 48 | 100 | 6.4 | 38 |
| 2 | 102 | 61 | 120 | 6.4 | 51 |
| 2½ | 107 | 73 | 140 | 6.4 | 51 |
| 3 | 133 | 89 | 150 | 6.4 | 64 |
| 4 | 172 | 114 | 190 | 9.7 | 64 |
| 6 | 219 | 168 | 240 | 12.7 | 76 |
| 8 | 276 | 219 | 300 | 12.7 | 76 |
| 10 | 337 | 273 | 360 | 15.7 | 102 |
| 12 | 406 | 324 | 430 | 19.1 | 102 |
| 16 | 511 | 406 | 460 | 22.4 | 108 |
| 20 | 603 | 508 | 635 | 28.4 | 121 |
| 24 | 714 | 610 | 750 | 31.8 | 140 |
Class 300 Spectacle Blind Flange Dimensions (ASME B16.48)
Class 300 flanges handle moderate-pressure service up to approximately 720 psi at 100°F in carbon steel.
| NPS | Outside Ø (A) (mm) | Inside Ø (B) (mm) | Centerline (C) (mm) | Thickness (t) (mm) | Web Width (W) (mm) |
|---|---|---|---|---|---|
| 1/2 | 51 | 16 | 65 | 6.4 | 38 |
| 3/4 | 64 | 21 | 80 | 6.4 | 38 |
| 1 | 70 | 27 | 90 | 6.4 | 38 |
| 1¼ | 79 | 42 | 100 | 6.4 | 38 |
| 1½ | 92 | 48 | 115 | 6.4 | 38 |
| 2 | 108 | 61 | 125 | 9.7 | 51 |
| 2½ | 127 | 73 | 150 | 9.7 | 51 |
| 3 | 146 | 89 | 170 | 9.7 | 64 |
| 4 | 178 | 114 | 200 | 12.7 | 64 |
| 6 | 248 | 168 | 270 | 15.7 | 76 |
| 8 | 305 | 219 | 330 | 22.4 | 76 |
| 10 | 359 | 273 | 385 | 25.4 | 102 |
| 12 | 419 | 324 | 450 | 28.4 | 102 |
| 16 | 536 | 406 | 570 | 38.1 | 108 |
| 20 | 651 | 508 | 685 | 44.5 | 121 |
| 24 | 772 | 610 | 810 | 50.8 | 140 |
Need a specific size or class not shown? Contact us for Class 900 to 2500 dimensions, custom ODs, or non-standard materials — reply within 24 hours.
Class 600 Spectacle Blind Flange Dimensions (ASME B16.48)
Class 600 flanges are selected for high-pressure service up to approximately 1480 psi at ambient temperature.
| NPS | Outside Ø (A) (mm) | Inside Ø (B) (mm) | Centerline (C) (mm) | Thickness (t) (mm) | Web Width (W) (mm) |
|---|---|---|---|---|---|
| 1/2 | 51 | 16 | 65 | 6.4 | 38 |
| 3/4 | 64 | 21 | 80 | 6.4 | 38 |
| 1 | 70 | 27 | 90 | 6.4 | 57 |
| 1¼ | 79 | 37 | 100 | 9.7 | 57 |
| 1½ | 92 | 43 | 115 | 9.7 | 67 |
| 2 | 108 | 55 | 125 | 9.7 | 57 |
| 2½ | 127 | 67 | 150 | 12.7 | 67 |
| 3 | 146 | 83 | 170 | 12.7 | 67 |
| 4 | 191 | 108 | 215 | 15.7 | 76 |
| 6 | 264 | 162 | 290 | 22.4 | 86 |
| 8 | 318 | 212 | 350 | 28.4 | 95 |
| 10 | 397 | 265 | 430 | 35.1 | 105 |
| 12 | 454 | 315 | 490 | 41.1 | 105 |
| 16 | 562 | 397 | 605 | 50.8 | 124 |
| 20 | 679 | 497 | 725 | 63.5 | 133 |
| 24 | 787 | 597 | 840 | 73.2 | 152 |
Class 900 Spectacle Blind Flange Dimensions (ASME B16.48)
Class 900 spectacle blind flanges are for high-pressure applications up to approximately 2220 psi at 100°F in carbon steel.
| NPS | Outside Ø A (mm) | Inside Ø B (mm) | Centerline C (mm) | Thickness t (mm) | Web Width W (mm) |
|---|---|---|---|---|---|
| 1/2 | 51 | 16 | 65 | 12.7 | 38 |
| 3/4 | 64 | 21 | 80 | 12.7 | 38 |
| 1 | 70 | 27 | 90 | 15.7 | 57 |
| 1½ | 95 | 43 | 120 | 19.1 | 67 |
| 2 | 114 | 55 | 135 | 19.1 | 57 |
| 3 | 152 | 83 | 175 | 22.4 | 67 |
| 4 | 203 | 108 | 225 | 25.4 | 76 |
| 6 | 292 | 162 | 320 | 34.9 | 95 |
| 8 | 368 | 212 | 400 | 41.1 | 105 |
| 10 | 451 | 265 | 485 | 50.8 | 115 |
| 12 | 508 | 315 | 550 | 57.2 | 115 |
Class 1500 Spectacle Blind Flange Dimensions (ASME B16.48)
Class 1500 flanges are for very high-pressure service up to approximately 3705 psi at 100°F in carbon steel.
| NPS | Outside Ø A (mm) | Inside Ø B (mm) | Centerline C (mm) | Thickness t (mm) | Web Width W (mm) |
|---|---|---|---|---|---|
| 1/2 | 51 | 13 | 65 | 15.7 | 38 |
| 3/4 | 64 | 18 | 80 | 15.7 | 38 |
| 1 | 70 | 24 | 90 | 19.1 | 57 |
| 1½ | 95 | 38 | 120 | 25.4 | 67 |
| 2 | 114 | 48 | 135 | 25.4 | 57 |
| 3 | 152 | 73 | 175 | 34.9 | 67 |
| 4 | 222 | 98 | 250 | 41.1 | 76 |
| 6 | 317 | 152 | 350 | 55.6 | 95 |
| 8 | 406 | 203 | 445 | 69.9 | 105 |
| 10 | 495 | 254 | 540 | 79.4 | 114 |
| 12 | 584 | 305 | 635 | 88.9 | 114 |
Class 2500 Spectacle Blind Flange Dimensions (ASME B16.48)
Class 2500 flanges serve extreme-pressure applications up to approximately 6170 psi at 100°F in carbon steel.
| NPS | Outside Ø A (mm) | Inside Ø B (mm) | Centerline C (mm) | Thickness t (mm) | Web Width W (mm) |
|---|---|---|---|---|---|
| 1/2 | 51 | 11 | 65 | 22.4 | 38 |
| 3/4 | 70 | 16 | 85 | 25.4 | 38 |
| 1 | 83 | 21 | 100 | 31.8 | 57 |
| 1½ | 111 | 33 | 135 | 38.1 | 67 |
| 2 | 140 | 43 | 165 | 44.5 | 57 |
| 3 | 184 | 62 | 215 | 57.2 | 67 |
| 4 | 251 | 87 | 285 | 73.0 | 76 |
| 6 | 356 | 133 | 395 | 98.6 | 95 |
Spectacle Blind Flanges Applications & Industries
Spectacle blind flanges are specified wherever a piping system must be positively isolated during maintenance, inspection or equipment changeover while retaining the ability to return to full flow without system disassembly. The following industries rely on spectacle blinds for operational safety:
- Oil & Gas: Offshore platforms, refineries, pipeline isolation, wellhead equipment
- Petrochemical: Process unit isolation, reactor systems, distillation columns
- Chemical Processing: Corrosive fluid handling, batch process isolation, safety systems
- Power Generation: Steam systems, boiler feeds, cooling water circuits
- Pharmaceutical: Sterile processing, clean-room applications, batch isolation — hygienic execution available, surface finish Ra ≤ 0.8 µm on request
- Food & Beverage: Sanitary CIP systems, process isolation — Ra ≤ 0.8 µm surface finish available
- Water Treatment: Municipal systems, desalination plants, wastewater facilities
- Marine & Offshore: Shipbuilding, FPSO units, subsea pipelines
Quality Assurance & Testing
Amardeep Steel operates under ISO 9001:2015 quality management and accepts third-party inspection by SGS, Bureau Veritas, Intertek and TUV on all export orders. Material traceability is maintained from raw material receipt through final dispatch.
Material Testing
- Chemical composition analysis (PMI — Positive Material Identification)
- Mechanical property testing (tensile, yield strength, elongation)
- Hardness testing (Brinell, Rockwell)
Non-Destructive Testing (NDT)
- Visual inspection for surface defects
- Dimensional inspection per ASME B16.48 tolerances
- Magnetic particle inspection (MPI) for surface cracks
- Ultrasonic testing (UT) for internal defects
- Radiography testing (RT) when specified
Certification & Documentation
- EN 10204 3.1 Manufacturer Test Certificates
- Raw material certificates with heat numbers
- 100% Radiography test reports (when required)
- Third-party inspection reports — SGS, Bureau Veritas, Intertek, TUV, PDIL, EIL
- Material traceability documentation
Why Choose Amardeep Steel for Spectacle Blind Flanges?
- ISO 9001:2015 Certified: Quality management systems certified by accredited body — certificate available on request.
- Complete Size Range: ½" to 48" NB, Class 150# to 2500#, all materials in stock or made-to-order.
- Third-Party Inspection Accepted: SGS, Bureau Veritas, Intertek, TUV, PDIL and EIL on all export orders.
- EN 10204 3.1 Certificates: Mill test certificates supplied with every order; PMI testing and Radiography available on request.
- Fast Dispatch: Standard stock sizes dispatch within 2-5 business days from Mumbai; non-standard and special-material items within 3-6 weeks.
- Global Export: Regular exports to UAE, Saudi Arabia, Qatar, UK, USA, Germany, Singapore, Australia, South Korea and South Africa.
- Custom Manufacturing: Non-standard sizes, special bore profiles and jackscrew tapped holes available for large-bore spectacle blinds to facilitate handling.
Frequently Asked Questions — Spectacle Blind Flanges
What is a spectacle blind flange?
A spectacle blind flange (ASME B16.48) is a figure-eight shaped device combining a solid blind disc and an open spacer ring, allowing operators to isolate or open a pipeline by rotating 180 degrees without dismantling the system.
What is the difference between a spectacle blind and a blind flange?
A spectacle blind provides both an open (flow) and closed (isolation) position in a single component, while a blind flange permanently seals a pipeline end with no open position available.
What standard governs spectacle blind flange dimensions?
ASME B16.48 governs line blanks, spectacle blinds and spacers. Spectacle blinds install between ASME B16.5 flanges. Dimensions including outside diameter, bore, thickness and web width are all defined in B16.48.
What is the difference between ASME B16.5 and ASME B16.48 for spectacle blinds?
B16.5 covers flanges (weld neck, slip-on, blind etc.). B16.48 specifically governs line blanks, spectacle blinds and spacers installed between B16.5 flanges. A spectacle blind must comply with B16.48 for dimensions and B16.5 for the mating flange face.
What material should I choose for a seawater spectacle blind?
Duplex Steel UNS S31803 or Super Duplex S32750 are the standard choices for seawater service, providing pitting resistance (PREN > 35) and chloride-stress corrosion resistance. For higher temperatures, Inconel 625 or Hastelloy C276 are specified.
What is the maximum size available for a spectacle blind flange?
Per ASME B16.48, spectacle blinds are standardised up to 24" NB in Classes 150-600 and up to 12" NB in Classes 900-2500. Amardeep Steel manufactures custom spectacle blinds up to 48" NB to drawing.
What is the maximum pressure class for a spectacle blind flange?
ASME B16.48 spectacle blind flanges are available up to Class 2500#, corresponding to approximately 6170 psi at 100°F in carbon steel. Custom higher-pressure blanks can be manufactured to client drawings.
Do spectacle blind flanges require gaskets?
Yes. Spectacle blinds install between existing flanges and require gaskets on both mating faces. The gasket type — spiral wound, ring type joint, or sheet — is selected based on pressure class, temperature, and flange face type (RF, FF, RTJ).
Related Flange Products
Explore our complete range of industrial flanges designed for various piping applications:
Flange Types
- Weld Neck Raised Face Flanges - High-pressure applications
- Slip-On Raised Face Flanges - Easy installation, cost-effective
- Blind Raised Face Flanges - Pipeline termination
- Socket Weld Raised Face Flanges - Small bore piping
- Screwed/Threaded Flanges - No welding required
- Orifice Flanges - Flow measurement
- Reducing Flanges - Size transitions
- Ring Type Joint Flanges - High-pressure sealing
- Groove & Tongue Flanges - Positive alignment
- Flat Face Flanges - Non-metallic gaskets
