ANSI B16.5 Weld Neck Flange


All Dimensions in Millimetres

Larger Sizes Available For Weld Neck flanges

Class 150 Flanges
NB Size
Inch. MM A B C D E F G H J No. holes
1/2" 15 89.00 60.30 35.00 30.00 21.30 48.00 11.10 1.60 15.90 4
3/4" 20 98.00 69.80 43.00 38.00 26.70 52.00 12.70 1.60 15.90 4
1" 25 108.00 79.40 51.00 49.00 33.40 56.00 14.30 1.60 15.90 4
1-1/4" 32 117.00 88.90 64.00 59.00 42.20 57.00 15.90 1.60 15.90 4
1-1/2" 40 127.00 98.40 73.00 65.00 48.30 62.00 17.50 1.60 15.90 4
2" 50 152.00 120.60 92.00 78.00 60.30 64.00 19.00 1.60 19.00 4
2-1/2" 65 178.00 139.70 105.00 90.00 73.00 70.00 22.20 1.60 19.00 4
3" 80 190.00 152.40 127.00 108.00 88.90 70.00 23.80 1.60 19.00 4
3-1/2" 90 216.00 177.80 140.00 122.00 101.60 71.00 23.80 1.60 19.00 8
4" 100 229.00 190.50 157.00 135.00 114.30 76.00 23.80 1.60 19.00 8
Class 300 Flanges
NB Size
Inch. MM A B C D E F G H J No. holes
1/2" 15 95.00 66.70 35.00 38.00 21.30 52.00 14.30 1.60 15.90 4
3/4" 20 117.00 82.60 43.00 48.00 26.70 57.00 15.90 1.60 19.00 4
1" 25 124.00 88.90 51.00 54.00 33.40 62.00 17.50 1.60 19.00 4
1-1/4" 32 133.00 98.40 64.00 64.00 42.20 65.00 19.00 1.60 19.00 4
1-1/2" 40 156.00 114.30 73.00 70.00 48.30 68.00 20.60 1.60 22.20 4
2" 50 165.00 127.00 92.00 84.00 60.30 70.00 22.20 1.60 19.00 8
2-1/2" 65 190.00 149.20 105.00 100.00 73.00 76.00 25.40 1.60 22.20 8
3" 80 210.00 168.30 127.00 117.00 88.90 79.00 28.60 1.60 22.20 8
3-1/2" 90 229.00 184.20 140.00 133.00 101.60 81.00 30.20 1.60 22.20 8
4" 100 254.00 200.00 157.00 146.00 114.30 86.00 31.80 1.60 22.20 8
Class 600 Flanges
NB Size
Inch. MM A B C D E F G H J No. holes
1/2" 15 95.00 66.70 35.00 38.00 21.30 52.00 20.70 6.40 15.90 4
3/4" 20 117.00 82.60 43.00 48.00 26.70 57.00 22.30 6.40 19.00 4
1" 25 124.00 88.90 51.00 54.00 33.40 62.00 23.90 6.40 19.00 4
1-1/4" 32 133.00 98.40 64.00 64.00 42.20 67.00 27.00 6.40 19.00 4
1-1/2" 40 156.00 114.30 73.00 70.00 48.30 70.00 28.80 6.40 22.20 4
2" 50 165.00 127.00 92.00 84.00 60.30 73.00 31.80 6.40 19.00 8
2-1/2" 65 190.00 149.20 105.00 100.00 73.00 79.00 35.00 6.40 22.20 8
3" 80 210.00 168.30 127.00 117.00 88.90 83.00 38.20 6.40 22.20 8
3-1/2" 90 229.00 184.20 140.00 133.00 101.60 86.00 41.30 6.40 25.40 8
4" 100 254.00 215.90 157.00 152.00 114.30 102.00 44.50 6.40 25.40 8
Class 900 Flanges
NB Size
Inch. MM A B C D E F G H J No. holes
1/2" 15 121.00 82.60 35.00 38.00 21.30 60.00 22.20 6.40 22.20 4
3/4" 20 130.00 88.90 43.00 44.00 26.70 70.00 25.40 6.40 22.20 4
1" 25 149.00 101.60 51.00 52.00 33.40 73.00 28.60 6.40 25.40 4
1-1/4" 32 159.00 111.10 64.00 64.00 42.20 73.00 28.60 6.40 25.40 4
1-1/2" 40 178.00 123.80 73.00 70.00 48.30 83.00 31.80 6.40 28.60 4
2" 50 216.00 165.10 92.00 105.00 60.30 102.00 38.10 6.40 25.40 8
2-1/2" 65 244.00 190.50 105.00 124.00 73.00 105.00 41.30 6.40 28.60 8
3" 80 241.00 190.50 127.00 127.00 88.90 102.00 38.10 6.40 25.40 8
4" 100 292.00 235.00 157.00 159.00 114.30 114.00 44.40 6.40 31.80 8
Class 1500 Flanges
NB Size
Inch. MM A B C D E F G H J No. holes
1/2" 15 121.00 82.60 35.00 38.00 21.30 60.00 22.20 6.40 22.20 4
3/4" 20 130.00 88.90 43.00 44.00 26.70 70.00 25.40 6.40 22.20 4
1" 25 149.00 101.60 51.00 52.00 33.40 73.00 28.60 6.40 25.40 4
1-1/4" 32 159.00 111.10 64.00 64.00 42.20 73.00 28.60 6.40 25.40 4
1-1/2" 40 178.00 123.80 73.00 70.00 48.30 83.00 31.80 6.40 28.60 4
2" 50 216.00 165.10 92.00 105.00 60.30 102.00 38.10 6.40 25.40 8
2-1/2" 65 244.00 190.50 105.00 124.00 73.00 105.00 41.30 6.40 28.60 8
3" 80 267.00 203.20 127.00 133.00 88.90 117.00 47.60 6.40 31.80 8
4" 100 311.00 241.30 157.00 162.00 114.30 124.00 54.00 6.40 34.90 8
Class 2500 Flanges
NB Size
Inch. MM A B C D E F G H J No. holes
1/2" 15 133.00 88.90 35.00 43.00 21.30 73.00 30.20 6.40 22.20 4
3/4" 20 140.00 95.20 43.00 51.00 26.70 79.00 31.70 6.40 22.20 4
1" 25 159.00 107.90 51.00 57.00 33.40 89.00 34.90 6.40 25.40 4
1-1/4" 32 184.00 130.20 64.00 73.00 42.20 95.00 38.10 6.40 28.60 4
1-1/2" 40 203.00 146.00 73.00 79.00 48.30 111.00 44.40 6.40 31.80 4
2" 50 235.00 171.40 92.00 95.00 60.30 127.00 50.80 6.40 28.60 8
2-1/2" 65 267.00 196.80 105.00 114.00 73.00 143.00 57.10 6.40 31.80 8
3" 80 305.00 228.60 127.00 133.00 88.90 168.00 66.70 6.40 34.90 8
4" 100 365.00 273.00 157.00 165.00 114.30 190.00 76.20 6.40 41.30 8

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