ASME B16.48 Spectacle Blind Dimensions (Figure-8)
This chart gives ASME B16.48 spectacle blind (figure-8 blank) dimensions in millimetres for raised-face Class 150, 300 and 600 flanges — outside and inside diameter, centre-to-centre distance, thickness and web width. A spectacle blind is fitted between two flanges to positively isolate a line: the solid end blocks flow, the ring end lets it through.
Teshi Group manufactures spectacle blinds, spades and ring spacers in India in carbon, low-temperature, alloy, stainless and duplex steel.
Key to dimensions
- A
- Outside diameter of blank and ring
- B
- Inside diameter of the ring (spacer) end
- C
- Centre line distance between blank and ring
- t
- Thickness
- W
- Web (tie bar) width
ASME B16.48 Spectacle Blind Dimensions (Figure-8) — tables
Spectacle blind, RF — Class 150 (mm)
| NPS | AOutside dia · mm | BInside dia · mm | CCentre line · mm | tThickness · mm | WWeb width · mm |
|---|---|---|---|---|---|
| 1/2" | 45 | 16 | 60 | 3 | 38 |
| 3/4" | 54 | 21 | 70 | 3 | 38 |
| 1" | 64 | 27 | 80 | 3 | 38 |
| 1 1/2" | 83 | 48 | 100 | 6.4 | 38 |
| 2" | 102 | 61 | 120 | 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 |
| 14" | 448 | 356 | 475 | 19.1 | 108 |
| 16" | 511 | 406 | 460 | 22.4 | 108 |
| 18" | 546 | 457 | 580 | 25.4 | 114 |
| 20" | 603 | 508 | 635 | 28.4 | 121 |
| 24" | 714 | 610 | 750 | 31.8 | 140 |
Spectacle blind, RF — Class 300 (mm)
| NPS | AOutside dia · mm | BInside dia · mm | CCentre line · mm | tThickness · mm | WWeb width · mm |
|---|---|---|---|---|---|
| 1/2" | 51 | 16 | 65 | 6.4 | 38 |
| 3/4" | 64 | 21 | 80 | 6.4 | 38 |
| 1" | 70 | 27 | 90 | 6.4 | 38 |
| 1 1/2" | 92 | 48 | 115 | 6.4 | 38 |
| 2" | 108 | 61 | 125 | 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 |
| 14" | 483 | 356 | 515 | 31.8 | 108 |
| 16" | 536 | 406 | 570 | 38.1 | 108 |
| 18" | 594 | 457 | 630 | 41.1 | 114 |
| 20" | 651 | 508 | 685 | 44.5 | 121 |
| 24" | 772 | 610 | 810 | 50.8 | 140 |
Spectacle blind, RF — Class 600 (mm)
| NPS | AOutside dia · mm | BInside dia · mm | CCentre line · mm | tThickness · mm | WWeb width · mm |
|---|---|---|---|---|---|
| 1/2" | 51 | 16 | 65 | 6.4 | 38 |
| 3/4" | 64 | 21 | 80 | 6.4 | 38 |
| 1" | 70 | 27 | 90 | 6.4 | 57 |
| 1 1/2" | 92 | 43 | 115 | 9.7 | 67 |
| 2" | 108 | 55 | 125 | 9.7 | 57 |
| 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 |
| 14" | 489 | 346 | 525 | 44.5 | 114 |
| 16" | 562 | 397 | 605 | 50.8 | 124 |
| 18" | 610 | 448 | 655 | 53.8 | 133 |
| 20" | 679 | 497 | 725 | 63.5 | 133 |
| 24" | 787 | 597 | 840 | 73.2 | 152 |
Notes
- All dimensions are in millimetres.
- Web (tie bar) thickness: 6 mm minimum, or equal to t if t is less than 6 mm.
- Reference values for estimation and checking. Verify against the current edition of the standard and the purchase specification before design, purchase or fabrication.
Reference information compiled from the published standard for convenience. It does not replace the current edition of the governing standard, which takes precedence. Verify critical dimensions and properties before design, purchase or fabrication. Teshi Engineers & Sales Promoters (P) Ltd accepts no liability for errors or omissions.
FAQ
ASME B16.48 Spectacle Blind dimensions (Figure-8): common questions
What is a spectacle blind?
A figure-8 shaped plate with a solid blank at one end and a ring spacer at the other, joined by a web. It is installed between flanges and rotated to open or isolate the line.
What is dimension C on a spectacle blind?
C is the centre-to-centre distance between the blank and the ring, which equals the flange bolt circle geometry for that size and class.
Does Teshi Group make spectacle blinds?
Yes — spectacle blinds, spades and ring spacers to ASME B16.48 in all classes, and larger sizes to drawing.
Related products, data sheets and standards
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