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Weld Neck Flange Dimensions – Class 150 to Class 2500

Weld neck flange dimensions are covered in ASME B16.5 – which covers Pipe Flanges and Flanged Fittings for size NPS ½” to 24” for above NPS 26” to 60” it should be as per ASME B16.47.

During dimensional inspection of flange, you should check for

  • Outer & Inner Diameter of body
  • Bolt Circle & Bolt hole Diameter
  • the thickness of weld end
  • Length of the Hub and
  • Straightness and alignment of the bolt hole

weld neck flange dimensions

Class 150 Weld Neck Flange Dimensions

Size in Inch Size in mm Outer Diameter Flange Thickness Hub OD Weld Neck OD Welding Neck Length Bore RF Diameter RF Height PCD Weld Face
    A B C D E F G H I J
1/2 15 90 9.6 30 21.3 46 Refer Note 34.9 2 60.3 1.6
3/4 20 100 11.2 38 26.7 51 42.9 2 69.9 1.6
1 25 110 12.7 49 33.4 54 50.8 2 79.4 1.6
1 1/4 32 115 14.3 59 42.2 56 63.5 2 88.9 1.6
1 1/2 40 125 15.9 65 48.3 60 73 2 98.4 1.6
2 50 150 17.5 78 60.3 62 92.1 2 120.7 1.6
2 1/2 65 180 20.7 90 73 68 104.8 2 139.7 1.6
3 80 190 22.3 108 88.9 68 127 2 152.4 1.6
3 1/2 90 215 22.3 122 101.6 70 139.7 2 177.8 1.6
4 100 230 22.3 135 114.3 75 157.2 2 190.5 1.6
5 125 255 22.3 164 141.3 87 185.7 2 215.9 1.6
6 150 280 23.9 192 168.3 87 215.9 2 241.3 1.6
8 200 345 27 246 219.1 100 269.9 2 298.5 1.6
10 250 405 28.6 305 273 100 323.8 2 362 1.6
12 300 485 30.2 365 323.8 113 381 2 431.8 1.6
14 350 535 33.4 400 355.6 125 412.8 2 476.3 1.6
16 400 595 35 457 406.4 125 469.9 2 539.8 1.6
18 450 635 38.1 505 457.2 138 533.4 2 577.9 1.6
20 500 700 41.3 559 508 143 584.2 2 635 1.6
24 600 815 46.1 663 610 151 692.2 2 749.3 1.6

Note: Welding Neck bore is derived from the pipe schedule

Class 150 Weld Neck Flange Stud & Bolt Dimesions

Size in Inch Size in mm No of Bolts Bolt Size UNC Machine Bolt Length RF Stud Length Hole Size ISO Stud Size Weight in kg
1/2 15 4 1/2 50 55 5/8 M14 0.6
3/4 20 4 1/2 50 65 5/8 M14 0.9
1 25 4 1/2 55 65 5/8 M14 1.4
1 1/4 32 4 1/2 55 70 5/8 M14 1.4
1 1/2 40 4 1/2 65 70 5/8 M14 1.8
2 50 4 5/8 70 85 3/4 M16 2.7
2 1/2 65 4 5/8 75 90 3/4 M16 3.7
3 80 4 5/8 75 90 3/4 M16 4.6
3 1/2 90 8 5/8 75 90 3/4 M16 5.5
4 100 8 5/8 75 90 3/4 M16 6.8
5 125 8 3/4 85 95 7/8 M20 8.7
6 150 8 3/4 85 100 7/8 M20 10.9
8 200 8 3/4 90 110 7/8 M20 17.7
10 250 12 7/8 100 115 1 M24 24
12 300 12 7/8 100 120 1 M24 37
14 350 12 1 115 135 1 1/8 M27 50
16 400 16 1 115 135 1 1/8 M27 64
18 450 16 1 1/8 125 145 1 1/4 M30 68
20 500 20 1 1/8 140 160 1 1/4 M30 82
24 600 20 1 1/4 150 170 1 3/8 M33 118

Class 300 Weld Neck Flange Dimensions

Size in Inch Size in mm Outer Diameter Flange Thickness Hub OD Weld Neck OD Welding Neck Length Bore RF Diameter RF Height PCD Weld Face
    A B C D E F G H I J
1/2 15 95 12.7 38 21.3 51 Refer Note 34.9 2 66.7 1.6
3/4 20 115 14.3 48 26.7 56 42.9 2 82.6 1.6
1 25 125 15.9 54 33.4 60 50.8 2 88.9 1.6
1 1/4 32 135 17.5 64 42.2 64 63.5 2 98.4 1.6
1 1/2 40 155 19.1 70 48.3 67 73 2 114.3 1.6
2 50 165 20.7 84 60.3 68 92.1 2 127 1.6
2 1/2 65 190 23.9 100 73 75 104.8 2 149.2 1.6
3 80 210 27 117 88.9 78 127 2 168.3 1.6
3 1/2 90 230 28.6 133 101.6 79 139.7 2 184.2 1.6
4 100 255 30.2 146 114.3 84 157.2 2 200 1.6
5 125 280 33.4 178 141.3 97 185.7 2 235 1.6
6 150 320 35 206 168.3 97 215.9 2 269.9 1.6
8 200 380 39.7 260 219.1 110 269.9 2 330.2 1.6
10 250 445 46.1 321 273 116 323.8 2 387.4 1.6
12 300 520 49.3 375 323.8 129 381 2 450.8 1.6
14 350 585 52.4 425 355.6 141 412.8 2 514.4 1.6
16 400 650 55.6 483 406.4 144 469.9 2 571.5 1.6
18 450 710 58.8 533 457 157 533.4 2 628.6 1.6
20 500 775 62 587 508 160 584.2 2 685.8 1.6
24 600 915 68.3 702 610 167 692.2 2 812.8 1.6

Note: Welding Neck bore is derived from the pipe schedule

Class 300 Weld Neck Flange Stud & Bolt Dimesions

Size in Inch Size in mm No of Bolts Bolt Size UNC Machine Bolt Length RF Stud Length Hole Size ISO Stud Size Weight in kg
1/2 15 4 1/2 55 65 5/8 M14 1.4
3/4 20 4 5/8 65 75 3/4 M16 1.4
1 25 4 5/8 65 75 3/4 M16 1.8
1 1/4 32 4 5/8 70 85 3/4 M16 2.3
1 1/2 40 4 3/4 75 90 7/8 M20 3.2
2 50 8 5/8 75 90 3/4 M16 4.1
2 1/2 65 8 3/4 85 100 7/8 M20 5.5
3 80 8 3/4 90 110 7/8 M20 6.8
3 1/2 90 8 3/4 95 110 7/8 M20 8.2
4 100 8 3/4 95 115 7/8 M20 11.4
5 125 8 3/4 110 120 7/8 M20 14.6
6 150 12 3/4 110 120 7/8 M20 19.1
8 200 12 7/8 120 140 1 M24 31
10 250 16 1 140 160 1 1/8 M27 42
12 300 16 1 1/8 145 170 1 1/4 M30 64
14 350 20 1 1/8 160 180 1 1/4 M30 82
16 400 20 1 1/4 165 190 1 3/8 M33 113
18 450 24 1 1/4 170 195 1 3/8 M33 145
20 500 24 1 1/4 185 205 1 3/8 M33 182
24 600 24 1 1/2 205 230 1 5/8 M39 264

Class 400 Weld Neck Flange Dimensions

Size in Inch Size in mm Outer Diameter Flange Thickness Hub OD Weld Neck OD Welding Neck Length Bore RF Diameter RF Height PCD Weld Face
    A B C D E F G H I J
1/2 15 95 14.3 38 21.3 52 Refer Note 34.9 7 66.7 1.6
3/4 20 115 15.9 48 26.7 57 42.9 7 82.6 1.6
1 25 125 17.5 54 33.4 62 50.8 7 88.9 1.6
1 1/4 32 135 20.7 64 42.2 67 63.5 7 98.4 1.6
1 1/2 40 155 22.3 70 48.3 70 73 7 114.3 1.6
2 50 165 25.4 84 60.3 73 92.1 7 127 1.6
2 1/2 65 190 28.6 100 73 79 104.8 7 149.2 1.6
3 80 210 31.8 117 88.9 83 127 7 168.3 1.6
3 1/2 90 230 35 133 101.6 86 139.7 7 184.2 1.6
4 100 255 35 146 114.3 89 157.2 7 200 1.6
5 125 280 38.1 178 141.3 102 185.7 7 235 1.6
6 150 320 41.3 206 168.3 103 215.9 7 269.9 1.6
8 200 380 47.7 260 219.1 117 269.9 7 330 1.6
10 250 445 54 321 273 124 323.8 7 387.4 1.6
12 300 520 57.2 375 323.8 137 381 7 450.8 1.6
14 350 585 60.4 425 355.6 149 412.8 7 514.4 1.6
16 400 650 63.5 483 406.4 152 469.9 7 571.5 1.6
18 450 710 66.7 533 457 165 533.4 7 628.6 1.6
20 500 775 69.9 587 508 168 584.2 7 685.8 1.6
24 600 915 76.2 702 610 175 692.2 7 812.8 1.6

Note: Welding Neck bore is derived from the pipe schedule

Class 400 Weld Neck Flange Stud & Bolt Dimesions

Size in Inch Size in mm No of Bolts Bolt Size UNC RF Stud Length Hole Size ISO Stud Size
1/2 15 4 1/2 75 5/8 M14
3/4 20 4 5/8 90 3/4 M16
1 25 4 5/8 90 3/4 M16
1 1/4 32 4 5/8 95 3/4 M16
1 1/2 40 4 3/4 110 7/8 M20
2 50 8 5/8 110 3/4 M16
2 1/2 65 8 3/4 120 7/8 M20
3 80 8 3/4 125 7/8 M20
3 1/2 90 8 7/8 140 1 M24
4 100 8 7/8 140 1 M24
5 125 8 7/8 145 1 M24
6 150 12 7/8 150 1 M24
8 200 12 1 170 1 1/8 M27
10 250 16 1 1/8 190 1 1/4 M30
12 300 16 1 1/4 205 1 3/8 M33
14 350 20 1 1/4 210 1 3/8 M33
16 400 20 1 3/8 220 1 1/2 M36
18 450 24 1 3/8 230 1 1/2 M36
20 500 24 1 1/2 240 1 3/4 M39
24 600 24 1 3/4 265 1 7/8 M45 


Class 600 Weld Neck Flange Dimensions






Size in Inch
Size in mm
Outer Diameter
Flange Thickness
Hub OD
Weld Neck OD
Welding Neck Length
Bore
RF Diameter
RF Height
PCD
Weld Face




 
 
A
B
C
D
E
F
G
H
I
J




1/2
15
95
14.3
38
21.3
52
Refer Note
34.9
7
66.7
1.6




3/4
20
115
15.9
48
26.7
57
42.9
7
82.6
1.6




1
25
125
17.5
54
33.4
62
50.8
7
88.9
1.6




1 1/4
32
135
20.7
64
42.2
67
63.5
7
98.4
1.6




1 1/2
40
155
22.3
70
48.3
70
73
7
114.3
1.6




2
50
165
25.4
84
60.3
73
92.1
7
127
1.6




2 1/2
65
190
28.6
100
73
79
104.8
7
149.2
1.6




3
80
210
31.8
117
88.9
83
127
7
168.3
1.6




3 1/2
90
230
35
133
101.6
86
139.7
7
184.2
1.6




4
100
275
38.1
152
114.3
102
157.2
7
215.9
1.6




5
125
330
44.5
189
141.3
114
185.7
7
266.7
1.6




6
150
355
47.7
222
168.3
117
215.9
7
292.1
1.6




8
200
420
55.6
273
219.1
133
269.9
7
349.2
1.6




10
250
510
63.5
343
273
152
323.8
7
431.8
1.6




12
300
560
66.7
400
323.8
156
381
7
489
1.6




14
350
605
69.9
432
355.6
165
412.8
7
527
1.6




16
400
685
76.2
495
406.4
178
469.9
7
603.2
1.6




18
450
745
82.6
546
457
184
533.4
7
654
1.6




20
500
815
88.9
610
508
190
584.2
7
723.9
1.6




24
600
940
101.6
718
610
203
692.2
7
838.2
1.6






Note: Welding Neck bore is derived from the pipe schedule








Class 600 Weld Neck Flange Stud & Bolt Dimesions






Size in Inch
Size in mm
No of Bolts
Bolt Size UNC
RF Stud Length
Hole Size
ISO Stud Size
Weight in kg




1/2
15
4
1/2
75
5/8
M14
1.5




3/4
20
4
5/8
90
3/4
M16
1.8




1
25
4
5/8
90
3/4
M16
1.8




1 1/4
32
4
5/8
95
3/4
M16
2.7




1 1/2
40
4
3/4
110
7/8
M20
3.7




2
50
8
5/8
110
3/4
M16
5.5




2 1/2
65
8
3/4
120
7/8
M20
8.2




3
80
8
3/4
125
7/8
M20
10.5




3 1/2
90
8
7/8
140
1
M24
11.8




4
100
8
7/8
145
1
M24
19.1




5
125
8
1
165
1 1/8
M27
31




6
150
12
1
170
1 1/8
M27
36




8
200
12
1 1/8
190
1 1/4
M30
55




10
250
16
1 1/4
215
1 3/8
M33
86




12
300
20
1 1/4
220
1 3/8
M33
102




14
350
20
1 3/8
235
1 1/2
M36
127




16
400
20
1 1/2
255
1 5/8
M39
177




18
450
20
1 5/8
275
1 3/4
M42
216




20
500
24
1 5/8
285
1 3/4
M42
268




24
600
24
1 7/8
330
2
M48
377















Class 900 Weld Neck Flange Dimensions






Size in Inch
Size in mm
Outer Diameter
Flange Thickness
Hub OD
Weld Neck OD
Welding Neck Length
Bore
RF Diameter
RF Height
PCD
Weld Face




 
 
A
B
C
D
E
F
G
H
I
J




1/2
15
120
22.3
38
21.3
60
Refer Note
34.9
7
82.6
1.6




3/4
20
130
25.4
44
26.7
70
42.9
7
88.9
1.6




1
25
150
28.6
52
33.4
73
50.8
7
101.6
1.6




1 1/4
32
160
28.6
64
42.2
73
63.5
7
111.1
1.6




1 1/2
40
180
31.8
70
48.3
83
73
7
123.8
1.6




2
50
215
38.1
105
60.3
102
92.1
7
165.1
1.6




2 1/2
65
245
41.3
124
73
105
104.8
7
190.5
1.6




3
80
240
38.1
127
88.9
102
127
7
190.5
1.6




4
100
290
44.5
159
114.3
114
157.2
7
235
1.6




5
125
350
50.8
190
141.3
127
185.7
7
279.4
1.6




6
150
380
55.6
235
168.3
140
215.9
7
317.5
1.6




8
200
470
63.5
298
219.1
162
269.9
7
393.7
1.6




10
250
545
69.9
368
273
184
323.8
7
469.9
1.6




12
300
610
79.4
419
323.8
200
381
7
533.4
1.6




14
350
640
85.8
451
355.6
213
412.8
7
558.8
1.6




16
400
705
88.9
508
406.4
216
469.9
7
616
1.6




18
450
785
101.6
565
457
229
533.4
7
685.8
1.6




20
500
855
108
622
508
248
584.2
7
749.3
1.6




24
600
1040
139.7
749
610
292
692.2
7
901.7
1.6






Note: Welding Neck bore is derived from the pipe schedule


Class 900 Weld Neck Flange Stud & Bolt Dimesions






Size in Inch
Size in mm
No of Bolts
Bolt Size UNC
RF Stud Length
Hole Size
ISO Stud Size
Weight in kg




1/2
15
4
3/4
110
7/8
M20
2.3




3/4
20
4
3/4
115
7/8
M20
2.7




1
25
4
7/8
125
1
M24
4.1




1 1/4
32
4
7/8
125
1
M24
4.6




1 1/2
40
4
1
140
1 1/8
M27
5.9




2
50
8
7/8
145
1
M24
11.5




2 1/2
65
8
1
160
1 1/8
M27
16.5




3
80
8
7/8
145
1
M24
14




4
100
8
1 1/8
170
1 1/4
M30
23




5
125
8
1 1/4
190
1 3/8
M33
39.5




6
150
12
1 1/8
190
1 1/4
M30
50




8
200
12
1 3/8
220
1 1/2
M36
80




10
250
16
1 3/8
235
1 1/2
M36
118




12
300
20
1 3/8
255
1 1/2
M36
148




14
350
20
1 1/2
275
1 5/8
M39
182




16
400
20
1 5/8
285
1 3/4
M42
225




18
450
20
1 7/8
325
2
M48
300




20
500
20
2
350
2 1/8
M52
373




24
600
20
2 1/2
440
2 5/8
M64
680















Class 1500 Weld Neck Flange Dimensions






Size in Inch
Size in mm
Outer Diameter
Flange Thickness
Hub OD
Weld Neck OD
Welding Neck Length
Bore
RF Diameter
RF Height
PCD
Weld Face




 
 
A
B
C
D
E
F
G
H
I
J




1/2
15
120
22.3
38
21.3
60
Refer Note
34.9
7
82.6
1.6




3/4
20
130
25.4
44
26.7
70
42.9
7
88.9
1.6




1
25
150
28.6
52
33.4
73
50.8
7
101.6
1.6




1 1/4
32
160
28.6
64
42.2
73
63.5
7
111.1
1.6




1 1/2
40
180
31.8
70
48.3
83
73
7
123.8
1.6




2
50
215
38.1
105
60.3
102
92.1
7
165.1
1.6




2 1/2
65
245
41.3
124
73
105
104.8
7
190.5
1.6




3
80
265
47.7
133
88.9
117
127
7
203.2
1.6




4
100
310
54
162
114.3
124
157.2
7
241.3
1.6




5
125
375
73.1
197
141.3
156
185.7
7
292.1
1.6




6
150
395
82.6
229
168.3
171
215.9
7
317.5
1.6




8
200
485
92.1
292
219.1
213
269.9
7
393.7
1.6




10
250
585
108
368
273
254
323.8
7
482.6
1.6




12
300
675
123.9
451
323.8
283
381
7
571.5
1.6




14
350
750
133.4
495
355.6
298
412.8
7
635
1.6




16
400
825
146.1
552
406.4
311
469.9
7
704.8
1.6




18
450
915
162
597
457
327
533.4
7
774.7
1.6




20
500
985
177.8
641
508
356
584.2
7
831.8
1.6




24
600
1170
203.2
762
610
406
692.2
7
990.6
1.6






Note: Welding Neck bore is derived from the pipe schedule


Class 1500 Weld Neck Flange Stud & Bolt Dimesions






Size in Inch
Size in mm
No of Bolts
Bolt Size UNC
RF Stud Length
Hole Size
ISO Stud Size
Weight in kg




1/2
15
4
3/4
110
7/8
M20
2.3




3/4
20
4
3/4
115
7/8
M20
2.7




1
25
4
7/8
125
1
M24
4.1




1 1/4
32
4
7/8
125
1
M24
4.6




1 1/2
40
4
1
140
1 1/8
M27
5.9




2
50
8
7/8
145
1
M24
11.4




2 1/2
65
8
1
160
1 1/8
M27
16.4




3
80
8
1 1/8
180
1 1/4
M30
21.8




4
100
8
1 1/4
195
1 3/8
M33
33




5
125
8
1 1/2
250
1 5/8
M39
59




6
150
12
1 3/8
260
1 1/2
M36
75




8
200
12
1 5/8
290
1 3/4
M42
125




10
250
12
1 7/8
335
2
M48
207




12
300
16
2
375
2 1/8
M52
314




14
350
16
2 1/4
405
2 3/8
M56
427




16
400
16
2 1/2
445
2 5/8
M64
568




18
450
16
2 3/4
495
2 7/8
M72
738




20
500
16
3
540
3 1/8
M76
932




24
600
16
3 1/2
615
3 5/8
M90
1511















Class 2500 Weld Neck Flange Dimensions






Size in Inch
Size in mm
Outer Diameter
Flange Thickness
Hub OD
Weld Neck OD
Welding Neck Length
Bore
RF Diameter
RF Height
PCD
Weld Face




 
 
A
B
C
D
E
F
G
H
I
J




1/2
15
135
30.2
43
21.3
73
Refer Note
34.9
7
88.9
1.6




3/4
20
140
31.8
51
26.7
79
42.9
7
95.2
1.6




1
25
160
35
57
33.4
89
50.8
7
108
1.6




1 1/4
32
185
38.1
73
42.2
95
63.5
7
130.2
1.6




1 1/2
40
205
44.5
79
48.3
111
73
7
146
1.6




2
50
235
50.9
95
60.3
127
92.1
7
171.4
1.6




2 1/2
65
265
57.2
114
73
143
104.8
7
196.8
1.6




3
80
305
66.7
133
88.9
168
127
7
228.6
1.6




4
100
355
76.2
165
114.3
190
157.2
7
273
1.6




5
125
420
92.1
203
141.3
229
185.7
7
323.8
1.6




6
150
485
108
235
168.3
273
215.9
7
368.3
1.6




8
200
550
127
305
219.1
318
269.9
7
438.2
1.6




10
250
675
165.1
375
273
419
323.8
7
539.8
1.6




12
300
760
184.2
441
323.8
464
381
7
619.1
1.6






Note: Welding Neck bore is derived from the pipe schedule


Class 2500 Weld Neck Flange Stud & Bolt Dimesions






Size in Inch
Size in mm
No of Bolts
Bolt Size UNC
RF Stud Length
Hole Size
ISO Stud Size
Weight in kg




1/2
15
4
3/4
120
7/8
M20
3.3




3/4
20
4
3/4
125
7/8
M20
3.7




1
25
4
7/8
140
1
M24
5.5




1 1/4
32
4
1
150
1 1/8
M27
7.8




1 1/2
40
4
1 1/8
170
1 1/4
M30
11.5




2
50
8
1
180
1 1/8
M27
19




2 1/2
65
8
1 1/8
195
1 1/4
M30
24




3
80
8
1 1/4
220
1 3/8
M33
42.8




4
100
8
1 1/2
255
1 5/8
M39
66




5
125
8
1 3/4
300
1 7/8
M45
111




6
150
8
2
345
2 1/8
M52
173




8
200
12
2
380
2 1/8
M52
264




10
250
12
2 1/2
490
2 5/8
M64
490




12
300
12
2 3/4
540
2 7/8
M72
695






Disclaimer –  Please check with ASME B16.5 Before using.











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