Spectacle blinds are commonly used to temporarily or permanently block flow through a specific section of pipe. While spectacle blinds may seem simple in design, determining the correct dimensions for them can be a complex process, as they must be precisely measured to ensure a proper fit within the piping system. In this post, we will explore the standard spectacle blind dimensions or 8 blinds which will be useful for selecting the right spectacle blind for your piping system.
Table of content:
What is spectacle blind?
Standard spectacle or 8 blind dimensions
What is spectacle blind?
A spectacle blind is basically made up of two metal discs attached to each other by a metal strip (known as the "spade") that is usually thicker than the pipe wall as shown in the figure. One is solid disc and the other is hollowed. The hollowed disc allows fluid flow and solid disc is used for positive isolation. You can simply rotate a spectacle blind by 180 degrees to close or open a pipe to allow fluid to pass.
An '8 blind' or a 'spectacle blind' is a piping fitting that is used for providing positive isolation. These fittings are used in industrial piping systems to temporarily or permanently block flow through a specific section of pipe. It is used in situations where it is necessary to isolate a section of piping for maintenance or repair work, or where it is desirable to have the option of blocking flow through a particular section of the system.
Standard spectacle or 8 blind dimensions
These standard of spectacle blinds are in specified in inches. They are as per as per ASME B16.48.
|
PIPE
SIZE |
150#
FLANGES |
|||||
|
A
|
B
|
C
|
D
|
E
|
F
|
|
|
1/2"
|
5/8
|
1-3/4
|
2-3/8
|
5/8
|
1-1/2
|
1/4
|
|
3/4"
|
13/16
|
2-1/8
|
2-3/4
|
5/8
|
1-1/2
|
1/4
|
|
1"
|
1-1/8
|
2-1/2
|
3-1/8
|
9/16
|
1-1/2
|
1/4
|
|
1-1/4"
|
1-5/8
|
2-7/8
|
3-1/2
|
9/16
|
1-1/2
|
1/4
|
|
1-1/2"
|
1-7/8
|
3-1/4
|
3-7/8
|
9/16
|
1-1/2
|
1/4
|
|
2"
|
2-3/8
|
4
|
4-3/4
|
11/16
|
2
|
1/4
|
|
2-1/2"
|
2-7/8
|
4-3/4
|
5-1/2
|
11/16
|
2
|
1/4
|
|
3"
|
3-1/2
|
5-1/4
|
6
|
11/16
|
2-1/2
|
1/4
|
|
3-1/2"
|
4
|
6-1/4
|
7
|
3/4
|
2-1/2
|
3/8
|
|
4"
|
4-1/2
|
6-3/4
|
7-1/2
|
3/4
|
2-1/2
|
3/8
|
|
5"
|
5-9/16
|
7-5/8
|
8-1/2
|
7/8
|
3
|
3/8
|
|
6"
|
6-5/8
|
8-5/8
|
9-1/2
|
7/8
|
3
|
1/2
|
|
8"
|
8-5/8
|
10-7/8
|
11-3/4
|
7/8
|
3
|
1/2
|
|
10"
|
10-3/4
|
13-1/4
|
14-1/4
|
1
|
4
|
5/8
|
|
12"
|
12-3/4
|
16
|
17
|
1
|
4
|
3/4
|
|
14"
|
14
|
17-5/8
|
18-3/4
|
1-1/8
|
4-1/4
|
3/4
|
|
16"
|
16
|
20-1/8
|
21-1/4
|
1-1/8
|
4-1/4
|
7/8
|
|
18"
|
18
|
21-1/2
|
22-3/4
|
1-1/4
|
4-1/2
|
1
|
|
20"
|
20
|
23-3/4
|
25
|
1-1/4
|
4-3/4
|
1-1/8
|
|
24"
|
24
|
28-1/8
|
29-1/2
|
1-3/8
|
5-1/2
|
1-1/4
|
|
PIPE
SIZE |
300#
FLANGES |
|||||
|
A
|
B
|
C
|
D
|
E
|
F
|
|
|
1/2"
|
5/8
|
2
|
2-5/8
|
5/8
|
1-1/2
|
1/4
|
|
3/4"
|
13/16
|
2-1/2
|
3-1/4
|
3/4
|
1-1/2
|
1/4
|
|
1"
|
1-1/8
|
2-3/4
|
3-1/2
|
11/16
|
1-1/2
|
1/4
|
|
1-1/4"
|
1-5/8
|
3-1/8
|
3-7/8
|
11/16
|
1-1/2
|
1/4
|
|
1-1/2"
|
1-7/8
|
3-5/8
|
4-1/2
|
7/8
|
2
|
1/4
|
|
2"
|
2-3/8
|
4-1/4
|
5
|
3/4
|
2
|
3/8
|
|
2-1/2"
|
2-7/8
|
5
|
5-7/8
|
7/8
|
2-1/2
|
3/8
|
|
3"
|
3-1/2
|
5-3/4
|
6-5/8
|
7/8
|
2-1/2
|
3/8
|
|
3-1/2"
|
4
|
6-3/8
|
7-1/4
|
7/8
|
2-1/2
|
1/2
|
|
4"
|
4-1/2
|
7
|
7-7/8
|
7/8
|
2-1/2
|
1/2
|
|
5"
|
5-5/8
|
8-3/8
|
9-1/4
|
7/8
|
3
|
5/8
|
|
6"
|
6-5/8
|
9-3/4
|
10-5/8
|
7/8
|
3
|
5/8
|
|
8"
|
8-5/8
|
12
|
13
|
1
|
3-1/2
|
7/8
|
|
10"
|
10-3/4
|
14-1/8
|
15-1/4
|
1-1/8
|
4
|
1
|
|
12"
|
12-3/4
|
16-1/2
|
17-3/4
|
1-1/4
|
4
|
1-1/8
|
|
14"
|
14
|
19
|
20-1/4
|
1-1/4
|
4-3/4
|
1-1/4
|
|
16"
|
16
|
21-1/8
|
22-1/2
|
1-3/8
|
4-7/8
|
1-1/2
|
|
18"
|
18
|
23-3/8
|
24-3/4
|
1-3/8
|
4-1/2
|
1-5/8
|
|
20"
|
20
|
25-5/8
|
27
|
1-3/8
|
4-3/4
|
1-3/4
|
|
24"
|
24
|
30-3/8
|
32
|
1-5/8
|
5-1/2
|
2
|
|
PIPE
SIZE |
600#
FLANGES |
|||||
|
A
|
B
|
C
|
D
|
E
|
F
|
|
|
1/2"
|
5/8
|
2
|
2-5/8
|
5/8
|
1-1/2
|
1/4
|
|
3/4"
|
13/16
|
2-1/2
|
3-1/4
|
3/4
|
1-1/2
|
1/4
|
|
1"
|
1-1/8
|
2-3/4
|
3-1/2
|
3/4
|
2-1/4
|
1/4
|
|
1-1/4"
|
1-7/16
|
3-1/8
|
3-7/8
|
3/4
|
2-1/4
|
3/8
|
|
1-1/2"
|
1-11/16
|
3-5/8
|
4-1/2
|
7/8
|
2-5/8
|
3/8
|
|
2"
|
2-1/8
|
4-1/4
|
5
|
3/4
|
2-1/4
|
3/8
|
|
2-1/2"
|
2-5/8
|
5
|
5-7/8
|
7/8
|
2-5/8
|
1/2
|
|
3"
|
3-1/4
|
5-3/4
|
6-5/8
|
7/8
|
2-5/8
|
1/2
|
|
3-1/2"
|
3-3/4
|
6-1/4
|
7-1/4
|
1
|
3
|
5/8
|
|
4"
|
4-1/4
|
7-1/2
|
8-1/2
|
1
|
3
|
5/8
|
|
5"
|
5-1/4
|
9-3/8
|
10-1/2
|
1-1/8
|
3-3/8
|
3/4
|
|
6"
|
6-3/8
|
10-3/8
|
11-1/2
|
1-1/8
|
3-3/8
|
7/8
|
|
8"
|
8-3/8
|
12-1/2
|
13-3/4
|
1-1/4
|
3-3/4
|
1-1/8
|
|
10"
|
10-7/16
|
15-5/8
|
17
|
1-3/8
|
4-1/8
|
1-3/8
|
|
12"
|
12-3/8
|
17-7/8
|
19-1/4
|
1-3/8
|
4-1/8
|
1-5/8
|
|
14"
|
13-5/8
|
19-1/4
|
20-3/4
|
1-1/2
|
4-1/2
|
1-3/4
|
|
16"
|
15-5/8
|
22-1/8
|
23-3/4
|
1-5/8
|
4-7/8
|
2
|
|
18"
|
17-5/8
|
24
|
25-3/4
|
1-3/4
|
5-1/4
|
2-1/8
|
|
20"
|
19-5/16
|
26-3/4
|
28-1/2
|
1-3/4
|
5-1/4
|
2-1/2
|
|
24"
|
23-1/2
|
31
|
33
|
2
|
6
|
2-7/8
|
|
PIPE
SIZE |
900#
FLANGES |
|||||
|
A
|
B
|
C
|
D
|
E
|
F
|
|
|
1/2"
|
0.625
|
2.375
|
3.25
|
-
|
1.50
|
1/4
|
|
3/4"
|
0.0825
|
2.625
|
3.50
|
0.875
|
1.625
|
1/4
|
|
1"
|
1.05
|
3.0
|
4.0
|
1.0
|
2.25
|
1/4
|
|
1-1/4"
|
1.44
|
3.375
|
4.375
|
1.0
|
2.25
|
3/8
|
|
1-1/2"
|
1.68
|
3.5
|
4.875
|
1.125
|
2.625
|
3/8
|
|
2"
|
2.16
|
5.5
|
6.5
|
1.0
|
2.25
|
1/2
|
|
2-1/2"
|
2.64
|
6.375
|
7.5
|
1.125
|
2.625
|
1/2
|
|
3"
|
3.25
|
6.5
|
7.5
|
1.0
|
2.625
|
5/8
|
|
4"
|
4.25
|
8.0
|
9.25
|
1.25
|
3.0
|
3/4
|
|
5"
|
5.3
|
9.625
|
11.0
|
1.375
|
3.375
|
7/8
|
|
6"
|
6.36
|
11.25
|
12.5
|
1.25
|
3.375
|
1
|
|
8"
|
8.33
|
14.0
|
15.5
|
1.5
|
3.75
|
1-3/8
|
|
10"
|
10.42
|
17.0
|
18.5
|
1.5
|
4.125
|
1-5/8
|
|
12"
|
12.39
|
19.5
|
21.0
|
1.5
|
4.125
|
1-7/8
|
|
14"
|
13.62
|
20.375
|
22.0
|
1.625
|
4.5
|
2-1/8
|
|
16"
|
15.62
|
22.5
|
24.25
|
1.75
|
4.875
|
2-3/8
|
|
18"
|
17.62
|
25.0
|
27.0
|
2.0
|
5.25
|
2-5/8
|
|
20"
|
19.56
|
27.375
|
29.5
|
2.125
|
5.25
|
2-7/8
|
|
24"
|
23.5
|
32.875
|
35.5
|
2.625
|
6.0
|
3-1/2
|
|
PIPE
SIZE |
1500#
FLANGES |
|||||
|
A
|
B
|
C
|
D
|
E
|
F
|
|
|
1/2"
|
0.625
|
2.375
|
3.25
|
-
|
1.50
|
1/4
|
|
3/4"
|
0.82
|
2.625
|
3.50
|
0.875
|
1.625
|
3/8
|
|
1"
|
1.05
|
3.0
|
4.0
|
1.0
|
2.5
|
3/8
|
|
1-1/4"
|
1.375
|
3.375
|
4.375
|
1.0
|
2.5
|
3/8
|
|
1-1/2"
|
1.61
|
3.75
|
4.875
|
1.125
|
2.75
|
1/2
|
|
2"
|
2.07
|
5.5
|
6.5
|
1.0
|
2.75
|
1/2
|
|
2-1/2"
|
2.47
|
6.375
|
7.5
|
1.125
|
3.0
|
5/8
|
|
3"
|
3.07
|
6.75
|
8.0
|
1.25
|
3.0
|
3/4
|
|
4"
|
4.03
|
8.125
|
9.5
|
1.375
|
3.5
|
7/8
|
|
5"
|
5.05
|
9.875
|
11.5
|
1.625
|
3.5
|
1-1/8
|
|
6"
|
6.06
|
11.0
|
12.5
|
1.5
|
3.5
|
1-3/8
|
|
8"
|
7.98
|
13.75
|
15.5
|
1.75
|
4.0
|
1-5/8
|
|
10"
|
10.02
|
17.0
|
19.0
|
2.0
|
4.5
|
2
|
|
12"
|
11.94
|
20.375
|
22.5
|
2.125
|
4.5
|
2-3/8
|
|
14"
|
13.12
|
22.625
|
25.0
|
2.375
|
5.0
|
2-5/8
|
|
16"
|
15.0
|
25.125
|
27.75
|
2.625
|
5.25
|
3
|
|
18"
|
16.88
|
27.625
|
30.5
|
2.875
|
5.75
|
3-3/8
|
|
20"
|
18.81
|
29.625
|
32.75
|
3.125
|
6.0
|
3-3/4
|
|
24"
|
22.62
|
35.375
|
39.0
|
3.625
|
7.0
|
4-3/8
|
|
PIPE
SIZE |
2500#
FLANGES |
|||||
|
A
|
B
|
C
|
D
|
E
|
F
|
|
|
1/2"
|
0.625
|
2.625
|
3.5
|
-
|
1.50
|
3/8
|
|
3/4"
|
0.82
|
2.875
|
3.75
|
0.875
|
1.625
|
3/8
|
|
1"
|
1.05
|
3.25
|
4.25
|
1.0
|
2.5
|
3/8
|
|
1-1/4"
|
1.38
|
4.0
|
5.125
|
1.125
|
2.5
|
1/2
|
|
1-1/2"
|
1.61
|
4.5
|
5.75
|
1.25
|
2.75
|
5/8
|
|
2"
|
2.07
|
5.625
|
6.75
|
1.125
|
2.75
|
5/8
|
|
2-1/2"
|
2.47
|
6.5
|
7.75
|
1.25
|
3.0
|
3/4
|
|
3"
|
3.07
|
7.625
|
9.0
|
1.375
|
3.0
|
7/8
|
|
4"
|
4.03
|
9.125
|
10.75
|
1.625
|
3.5
|
1-1/8
|
|
5"
|
5.05
|
10.875
|
12.75
|
1.875
|
3.5
|
1-3/8
|
|
6"
|
6.06
|
12.375
|
14.5
|
2.125
|
3.5
|
2
|
|
8"
|
7.81
|
15.125
|
17.25
|
2.125
|
4.0
|
2-1/8
|
|
10"
|
9.75
|
18.625
|
21.25
|
2.625
|
4.5
|
2-5/8
|
|
12"
|
11.37
|
21.5
|
24.375
|
2.875
|
4.5
|
3-1/8
|
