Fittings
No. Dia of of Bolts Bolts
Length of Studs 1/16 in Raised Face
Bolt Length
in
Length Thru Hub
Thickness
Weld Neck1
SO Threaded SW1
L a p J o in t
Blind1
in
in
in
in
in
Nominal Pipe Size
Flange OD
Dia of Bolt Circle
in
in
in
in
1/2 1/ 2
3 1/ 1/2 2
2 3/ 3/8 8
1/2 1/ 2
4
2 1/ 1/4 4
1 3/ 3/4 4
1 7/ 7/8 8
5/8 5/ 8
5/8 5/ 8
7/16 7/ 16
3/4
3 7/8
2 3/4
1/2
4
2 1/4
2
2 1/16
5/8
5/8
1/2
1
4 1/4
3 1/8
1/2
4
2 1/2
2
2 3/16
11/16
11/16
9/16
1 1/4
4 5/8
3 1/2
1/2
4
2 1/2
2 1/4
2 1/4
13/16
13/16
5/8
1 1/2
5
3 7/8
1/2
4
2 3/4
2 1/4
2 7/16
7/8
7/8
11/16
2
6
4 3/4
5/8
4
3
2 3/4
2 1/2
1
1
3/4
2 1/ 1/2 2
7
5 1/ 1/2 2
5/8
4
3 1/ 1/4 4
3
2 3/4
1 1/8
1 1/ 1/8 8
7/8 7/ 8
3
7 1/ 1/2 2
6
5/8
4
3 1/ 1/2 2
3
2 3/4
1 3/ 3/1 16
1 3/ 3/16 16
15/ 5/16 16
3 1/2
8 1/2
7
5/8
8
3 1/2
3
2 13/16
1 1/4
1 1/4
15/16
4
9
7 1/2
5/8
8
3 1/2
3
3
1 5/16
1 5/16
15/16
5
10
8 1/2
3/4
8
3 3/4
3 1/4
3 1/2
1 7/16
1 7/16
15/16
6
11
9 1/2
3/4
8
3 3/4
3 1/4
3 1/2
1 9/16
1 9/16
1
8
13 1/2
11 3/4
3/4 3/
8
4
3 1/2
4
1 3/4
1 3/4
1 1/8
10
16
14 1/4
7/8
12
4 1/2
3 3/4
4
1 15/16
1 15/16
1 3/16
12
19
17
7/8
12
4 1/2
4
4 1/2
2 3/16
2 3/16
1 1/4
14
21
18 3/4
1
12
5
4 1/4
5
2 1/4
3 1/8
1 3/8
16
23 1/2
21 1/4
1
16
5 1/4
4 1/2
5
2 1/2
3 7/16
1 7/16
18
15
22 3/4
1 1/8
16
5 3/4
4 3/4
5 1/2
2 11/16
3 13/16
1 9/16
20
17 1/2
25
1 1/8
20
6
5 1/4
5 11/16
2 7/8
1 11/16
22
29 1/ 1/2 2
27 1/ 1/4 4
1 1/ 1/4 4
20
6 1/ 1/2 2
5 1/ 1/2 2
5 7/ 7/8 8
3 1/ 1/8 8
1 13 13/1 /16 6
24
32
29 1/ 1/2 2
1 1/ 1/4 4
20
6 3/ 3/4 4
5 3/ 3/4 4
6
3 1/ 1/4 4
1 7/ 7/8 8
26
34 1/4 34
31 3/4
1 1/4
24
7
6
5
3 3/8
2
30
38 3/ 3/4 4
36
1 1/ 1/4 4
28
7 1/ 1/4 4
6 1/ 1/4 4
5 1/ 1/8 8
3 1/ 1/2 2
2 1/ 1/8 8
34
43 3/4
40 1/2
1 1/2
32 32
8
7
5 5/16
3 11/16
2 5/16
36
46
42 3/ 3/4 4
1 1/ 1/2 2
32
8 1/ 1/4 4
7
5 3/ 3/8 8
3 3/ 3/4 4
2 3/ 3/8 8
42
53
49 1/ 1/2 2
1 1/ 1/2 2
36
8 3/ 3/4 4
7 1/ 1/2 2
5 5/ 5/8 8
4
2 5/ 5/8 8
1
The 1/16” raised face fac e is included in the “Length thru th ru Hub” dimension of o f the Weld Neck (WN), Slip On O n (SO), Threaded, and Socket Weld (SW) flange, and also in the “Thickness” dimension of the Blind flange.
TABLE 7.2 ANSI B16.5 Flange dimensions for 150 lb flanges. Bolting arrangement for 125 lb cast iron (ANSI B 16.1) flanges are the same as for 150 lb ANSI B16.5 steel flanges.
153
154
Chapter 7
Nominal Pipe Size
Length of Studs 1/16” Raised Face
Bolt Length
in
in
Length Thru Hub
Thickness
Weld Neck1
SO Threaded SW1
Lap Joint
Blind 1
Flange OD
Diam of Bolt Circle
Diam of Bolts
in
in
in
in
1/2
3 3/4
2 5/8
1/2
4
2 1/2
2
2 1/16
7/8
7/8
9/16
3/4
4 5/8
3 1/4
5/8
4
2 3/4
2 1/2
2 1/4
1
1
5/8
1
4 7/8
3 1/2
5/8
4
3
25 1/2
2 7/16
1 1/16
1 1/16
11/16
1 1/4
5 1/4
3 7/8
5/8
4
3
2 3/4
2 9/16
1 1/16
1 1/16
3/4
1 1/2
6 1/8
4 1/2
3/4
4
3 1/2
3
2 11/16
1 3/16
1 3/16
13/16
2
6 1/2
5
5/8
8
3 1/4
3
2 3/4
1 5/16
1 5/16
7/8
2 1/2
7 1/2
5 7/8
3/4
8
3 3/4
3 1/4
3
1 1/2
1 1/2
1
3
8 1/4
6 5/8
3/4
8
4
3 1/2
3 1/8
1 11/16
1 11/16
1 1/8
3 1/2
9
7 1/4
3/4
8
4 1/4
3 3/4
3 3/16
1 3/4
1 3/4
1 3/16
4
10
7 7/8
3/4
8
4 1/4
3 3/4
3 3/8
1 7/8
1 7/8
1 1/4
5
11
9 1/4
3/4
8
4 1/2
4
3 7/8
2
2
1 3/8
3/4
12
4 3/4
4 1/4
3 7/8
2 1/16
2 1/16
1 7/16
7/8
12
5 1/4
4 3/4
4 3/8
2 7/16
2 7/16
1 5/8
6 8
12 1/2 10 5/8 15
13
No. of Bolts
10
17 1/2 15 1/4
1
16
6
5 1/4
4 5/8
2 5/8
3 3/4
1 7/8
12
20 1/2 17 3/4
1 1/8
16
6 1/2
5 3/4
5 1/8
2 7/8
4
2
20 1/4
1 1/8
20
6 3/4
6
5 5/8
3
4 3/8
2 1/8
25 1/2 22 1/2
1 1/4
20
7 1/4
6 1/2
5 3/4
3 1/4
4 3/4
2 1/4
14 16
23
18
28
24 3/4
1 1/4
24
7 1/2
6 3/4
6 1/4
3 1/2
5 1/8
2 3/8
20
30 1/2
27
1 1/4
24
8
7
6 3/8
3 3/4
5 1/2
2 1/2
22
33
29 1/4
1 1/2
24
8 3/4
7 1/2
6 1/2
4
6
2 5/8
24
36
32
1 1/2
24
9
7 3/4
6 5/8
4 3/16
2 3/4
1 5/8
28
10
8 3/4
7 1/4
7 1/4
3 1/8
39 1/4
1 3/4
28
11 1/4
10
8 1/4
8 1/4
3 5/8
47 1/2 43 1/2
1 7/8
28
12 1/4
10 3/4
9 1/8
9 1/8
4
26 30 34
38 1/4 34 1/2 43
36
50
46
2
32
12 3/4
11 1/4
9 1/2
9 1/2
4 1/8
42
57
52 3/4
2
36
13 3/4
13 1/2
10 7/8
10 7/8
4 5/8
1
The 1/16” raised face is included in the “Length thru Hub” dimension of the Weld Neck (WN), Slip On (SO), Threaded, and Socket Weld (SW) flange, and also in the “Thickness” dimension of the Blind flange.
TABLE 7.3 ANSI B16.5 Flange dimensions for 300 lb flanges. Bolting arrangement for 250 lb cast iron (ANSI B 16.1) flanges are the same as for 300 lb ANSI B16.5 steel flanges.
Fittings
Diam of Bolts
Length of Studs 1/4” Raised Face in
Length Thru Hub
Thickness
Nominal Pipe Size
Flange OD
Diam of Bolt Circle
in
in
in
in
1/2
3 3/4
2 5/8
1/2
4
3
3/4
4 5/8
3 1/4
5/8
4
3 1/4
1
4 7/8
3 1/2
5/8
4
3 1/2
1 1/4
5 1/4
3 7/8
5/8
4
3 3/4
1 1/2
6 1/8
4 1/2
3/4
4
4
2
6 1/2
5
5/8
8
4
2 1/2
7 1/2
5 7/8
3/4
8
4 1/2
3
8 1/4
6 5/8
3/4
8
4 3/4
3 1/2
9
7 1/4
7/8
8
5 1/4
4
10
7 7/8
7/8
8
5 1/4
3 1/2
2
2
1 3/8
5
11
9 1/4
7/8
8
6 1/2
4
2 1/8
2 1/8
1 1/2
6
12 1/2
10 5/8
7/8
12
5 3/4
4 1/16
2 1/4
2 1/4
1 5/8
8
15
13
1
12
6 1/2
4 5/8
2 11/16
2 11/16
1 7/8
10
17 1/2
15 1/4
1 1/8
16
7 1/4
4 7/8
2 7/8
4
2 1/8
12
20 1/2
17 3/4
1 1/4
16
7 3/4
5 3/8
3 1/8
4 1/4
2 1/4
14
23
20 1/4
1 1/4
20
8
5 7/8
3 5/16
4 5/8
2 3/8
16
25 1/2
22 1/2
1 3/8
20
8 1/2
6
3 11/16
5
2 1/2
18
28
24 3/4
1 3/8
24
8 3/4
6 1/2
3 7/8
5 3/8
2 5/8
20
30 1/2
27
1 1/2
24
9 1/2
6 5/8
4
5 3/4
2 3/4
22
33
29 1/4
1 5/8
24
10
6 3/4
4 1/4
24
36
32
1 3/4
24
10 1/2
6 7/8
4 1/2
26
38 1/4
34 1/2
1 3/4
28
11 1/2
7 5/8
7 5/8
3 1/2
30
43
39 1/4
2
28
13
8 5/8
8 5/8
4
34
47 1/2
43 1/2
2
28
13 3/4
9 1/2
9 1/2
4 3/8
36
50
46
2
32
14
9 7/8
9 7/8
4 1/2
42
57
52 3/4
2 1/2
36
16 1/4
11 3/8
11 3/8
5 1/8
No. of Bolts
Weld Neck1
SO Threaded SW1
Lap Joint
Blind 1
in
in
in
in
Use 600 lb
1
2 7/8 6 1/4
3
The 1/16” raised face is included in the “Length thru Hub” dimension of the Weld Neck (WN), Slip On (SO), Threaded, and Socket Weld (SW) flange, and also in the “Thickness” dimension of the Blind flange.
TABLE 7.4
ANSI B16.5 Flange dimensions for 400 lb flanges.
155
156
Chapter 7
Nominal Pipe Size
Flange OD
Diam of Bolt Circle
Diam of Bolts
in
in
in
in
1/2
3 3/4
2 5/8
1/2
3/4
4 5/8
3 1/4
1
4 7/8
1 1/4
Length of Studs 1/4” Raised Face
Length Thru Hub
Thickness
Weld Neck1
SO Threaded SW1
Lap Joint1
Blind1
in
in
in
in
in
4
3
2 1/16
7/8
7/8
9/16
5/8
4
3 1/4
2 1/4
1
1
5/8
3 1/2
5/8
4
3 1/2
2 7/16
1 1/16
1 1/6
11/16
5 1/4
3 7/8
5/8
4
3 3/4
2 5/8
1 1/8
1 1/8
13/16
1 1/2
6 1/8
4 1/2
3/4
4
4
2 3/4
1 1/4
1 1/4
7/8
2
6 1/2
6
5/8
8
4
2 7/8
1 7/16
1 7/16
1
2 1/2
7 1/2
5 7/8
3/4
8
4 1/2
3 1/8
1 5/8
1 5/8
1 1/8
3
8 1/4
6 5/8
3/4
8
4 3/4
3 1/4
1 13/16
1 13/16
1 1/4
3 1/2
9
7 1/4
7/8
8
5 1/4
3 3/8
1 15/16
1 15/16
1 3/8
4
10 3/4
8 1/2
7/8
8
5 1/2
4
2 1/8
2 1/8
1 1/2
5
13
10 1/2
1
8
6 1/4
4 1/2
2 3/8
2 3/8
1 3/4
6
14
11 1/2
1
12
6 1/2
4 5/8
2 5/8
2 5/8
1 7/8
8
16 1/2
13 3/4
1 1/8
12
7 1/2
5 1/4
3
3
2 3/16
10
20
17
1 1/4
16
8 1/4
6
3 3/8
4 3/8
2 1/2
12
22
19 1/4
1 1/4
20
8 1/2
6 1/8
3 5/8
4 5/8
2 5/8
14
23 3/4
20 3/4
1 3/8
20
9
6 1/2
3 11/16
5
2 3/4
16
27
23 3/4
1 1/2
20
9 3/4
7
4 3/16
5 1/2
3
18
29 1/4
25 3/4
1 5/8
20
10 1/2
7 1/4
4 5/8
6
3 1/4
20
32
28 1/2
1 5/8
24
11 1/4
7 1/2
5
6 1/2
3 1/2
22
34 1/4
30 5/8
1 3/4
24
12
7 3/4
5 1/4
24
37
33
1 7/8
24
12 3/4
8
5 1/2
26
40
36
1 7/8
28
13 1/4
8 3/4
8 3/4
4 1/4
30
44 1/2
40 1/4
2
28
14
9 3/4
9 3/4
4 1/2
34
49
44 1/2
2 1/4
28
15
10 5/8
10 5/8
4 3/4
36
51 3/4
47
2 1/2
28
15 3/4
11 1/8
11 1/8
4 7/8
42
58 3/4
53 3/4
2 3/4
28
17 1/2
12 3/4
No. of Bolts
1
3 3/4 7 1/4
4
5 1/2
The 1/16” raised face is included in the “Length thru Hub” dimension of the Weld Neck (WN), Slip On (SO), Threaded, and Socket Weld (SW) flange, and also in the “Thickness” dimension of the Blind flange.
TABLE 7.5
ANSI B16.5 Flange dimensions for 600 lb flanges.
Fittings
Pressure Class
25
125
250
800 ASTM
Material
ASTM A 126
Class
A
NPS (in)
4-36
ASTM A 126 A
42-96
1-12
ASTM A 126
B 1-12
14-24
A 30-48
1-12
A 126
B 1-12
Service Temp
Maximum Non-Shock Pressure
(°F)
(psig)
B
14-24
30-48
2-12
800
-20 to 150
45
25
175
200
150
150
400
500
300
300
200
40
25
165
190
135
115
370
460
280
250
225
35
25
155
180
130
100
355
440
270
225
250
30
25
150
175
125
85
340
415
260
200
275
25
25
145
170
120
65
325
395
250
175
300
140
165
110
50
310
375
240
150
325
130
155
105
295
355
230
125
265
315
210
375
145
425
130
270
450
125
250
Limitations: Class 25: Maximum pressure shall be limited to 25 psig when Class 25 cast iron flanges and flanged fittings are used for gaseous service. Tabulated pressure-temperature ratings above 25 psig for Class 25 cast iron flanges and flanged fittings are applicable for non-shock hydraulic service only. Class 250: When used for liquid service the tabulated pressure-temperature ratings in sizes 14 in and larger are applicable to Class 250 flanges only and not to Class 250 fittings. Class 800: The tabulated rating is not a steam rating and applies to non-shock hydraulic pressure only. TABLE 7.6
ANSI B16.1 Cast Iron Flange Temperature and Pressure Ratings.
Pressure Class PN Number Service Temperature
150 20
300 50
400 68
600 100
900 150
1500 250
2500 420
Maximum Non-Shock Pressure (psig)
(°F)
100
285
740
990
1480
2200
3705
6170
200
260
675
900
1350
2025
3375
5625
300
230
655
875
1315
1970
3280
5470
400
200
635
845
1270
1900
3170
5280
500
170
600
800
1200
1795
2995
4990
600
140
550
730
1095
1640
2735
4560
650
125
535
715
1075
1610
2685
4475
700
110
535
710
1065
1600
2665
4440
750
95
505
670
1010
1510
2520
4200
800 TABLE 7.7
NOT RECOMMENDED ABOVE 800 ANSI B16.5 Temperature and Pressure Ratings for ASTM A105 Carbon Steel Flange.
157
158
Chapter 7
Most of what the average engineer deals with is at moderate temperatures and pressures, say up to 300°F and 200 psig. That is, it falls into the realm of Class 150, ASTM A105 flanges. But sometimes we are faced with more demanding services, whether they are related to elevated temperatures, pressures, or corrosive fluids that require different metallurgy. In those cases, the reader is advised to obtain access to ANSI B16.5 (or B16.47) to determine the pressure rating at the particular temperature for that service. Do not rely on tables gleaned from generic sources, since these tend to generalize the term “carbon steel.” Carbon steel covers a lot of territory, and the difference in pressure rating for Class 300 flanges at 100°F can swing from 620 to 750 psig. Some tables list pressures for carbon steel flanges up to 1000°F, but ANSI B16.5 suggests that carbon steels not be used above 800°F. At those elevated temperatures, higher grades of stainless or the Group 3 nickel-molybdenum alloys should be used. Pressure classes of cast iron flanges are established by ANSI B16.1. These are rated at Classes 25,125, 250, and 800. The Class 125 flanges are always flat faced, and can be mated to 150 lb steel flanges. When this is done, there are two choices to prevent the cast iron flange from cracking due to the stress of bolting to a raised face flange: 1. Use low-strength bolting (less than 30 ksi minimum yield strength). 2. Machine off the raised face of the steel mating flange, and use a full face gasket
as shown in Figure 7.1 with intermediate or high-strength bolts. The same holds true for mating Class 250 cast iron flanges with 300 lb steel raised face flanges. Class 250 CI flanges have a raised face, and according to ANSI B16.5, both mating flange faces should be machined flat. In practice, sometimes you will see Class 250 CI raised face flanges installed against Class 300 steel flanges with ring gaskets as shown in Figure 7.2 and no machining. In these cases, the low-strength bolting should be used.
