A spectacle blind is generally a piece of metal that is cut to fit between two pipe flanges and usually sandwiched between two gaskets.  A spectacle blind is often made from two metal discs that are attached to each other by a small section of steel.  The shape is similar to a pair of glasses or “spectacles” – hence the name spectacle blind.  One end of the blind will have an opening to allow flow through the pipe during operation and the other end is solid to block flow during maintenance.  They are generally installed as a permanent device to separate process piping systems.

SPECTACLE BLIND DIMENSIONS

 

Ref. 3 4 6 8 10 12 14 16 18 20 24
A In/Po 5 1/8 6 1/2 8 10 1/2 13 15 17 19 21 23 28
mm 130 165 203 267 330 381 432 483 533 584 711
B In/Po Inside diameter of pipe, unless otherwise specified
mm
C In/Po 3 3 3/4 4 3/4 5
7/8
7 1/8 8 1/2 9 3/8 10
5/8
11 3/8 12 1/2 14 3/4
mm 76 95 121 149 181 216 238 270 289 317 375
D In/Po 2 2 2 1/2 2 1/2 3 3 3 3 4 4 4
mm 51 51 63 63 76 76 76 76 102 102 102
E In/Po 3/4 3/4 7/8 7/8 1 1 1 1/8 1 1/8 1 1/4 1 1/4 1 3/8
mm 19 19 22 22 25 25 29 29 32 32 35
F In/Po 5 3/4 6 1/2 7 1/2 8 3/4 10 11 1/2 12 1/2 13 3/4 14 1/2 15 3/4 18
mm 146 165 190 222 254 292 317 349 368 400 457
G In/Po 3/4 3/4 3/4 1 1 1 1 1 1 1 1
mm 19 19 19 25 25 25 25 25 25 25 25
H In/Po 3/4 3/4 3/4 3/4 3/4 3/4 3/4 3/4 3/4 3/4 3/4
mm 19 19 19 19 19 19 19 19 19 19 19
R In/Po 1 1 1 1 1 1 1 1 1 1 1
mm 25 25 25 25 25 25 25 25 25 25 25
T In/Po 3/16 3/16 1/4 3/8 3/8 1/2 1/2 5/8 5/8 3/4 3/4
mm 4.8 4.8 6.4 9.5 9.5 12.7 12.7 15.9 15.9 19 19

Notes

  1. Thickness, see T.
  2. Material: Stainless steel 304L-316L. Other alloys available upon request.
  3. Other designs and thicknesses available upon request.
  4. Tolerances: ±1/16”.