Welding Neck Orifice Class 300 Flanges
Welding Neck Orifice Class 300 Flanges
Welding Neck Orifice Class 300
  Drilling
  Nom  Size OD Thickness OD of RF Dia at Base Dia Bevel LTH Dia of Pressure Connection Bolt Circle Hole Dia # of Holes Bolt Dia
O C R X A Y TT        
in 1 4.88 1.50 2.00 2.12 1.32 3.25  1/4 3.50 0.69 4  5/8
mm   124.0 38.1 50.8 53.8 33.5 82.6 6.4 88.9 17.5   15.9
in 1 1/2 6.12 1.50 2.88 2.75 1.90 3.38  1/4 4.50 0.81 4  3/4
mm   155.4 38.1 73.2 69.9 48.3 85.9 6.4 114.3 20.6   19.1
in 2 6.50 1.50 3.62 3.31 2.38 3.38  1/4 5.00 0.69 8  5/8
mm   165.1 38.1 91.9 84.1 60.5 85.9 6.4 127.0 17.5   15.9
in 2 1/2 7.50 1.50 4.12 3.94 2.88 3.50  1/4 5.88 0.81 8  3/4
mm   190.5 38.1 104.6 100.1 73.2 88.9 6.4 149.4 20.6   19.1
in 3 8.25 1.50 5.00 4.62 3.50 3.50  3/8 6.62 0.81 8  3/4
mm   209.6 38.1 127.0 117.3 88.9 88.9 9.5 168.1 20.6   19.1
in 4 10.00 1.50 6.19 5.75 4.50 3.62  1/2 7.88 0.81 8  3/4
mm   254.0 38.1 157.2 146.1 114.3 91.9 12.7 200.2 20.6   19.1
in 6 12.50 1.50 8.50 8.12 6.63 3.94  1/2 10.62 0.88 12  3/4
mm   317.5 38.1 215.9 206.2 168.4 100.1 12.7 269.7 22.4   19.1
in 8 15.00 1.62 10.62 10.25 8.63 4.38  1/2 13.00 1.00 12  7/8
mm   381.0 41.1 269.7 260.4 219.2 111.3 12.7 330.2 25.4   22.2
in 10 17.50 1.88 12.75 12.62 10.75 4.62  1/2 15.25 1.12 16 1   
mm   444.5 47.8 323.9 320.5 273.1 117.3 12.7 387.4 28.4   25.4
in 12 20.50 2.00 15.00 14.75 12.75 5.12  1/2 17.75 1.25 16 1 1/8
mm   520.7 50.8 381.0 374.7 323.9 130.0 12.7 450.9 31.8   28.6
in 14 23.00 2.12 16.25 16.75 14.00 5.62  1/2 20.25 1.25 20 1 1/8
mm   584.2 53.8 412.8 425.5 355.6 142.7 12.7 514.4 31.8   28.6
in 16 25.50 2.25 18.50 19.00 16.00 5.75  1/2 22.50 1.38 20 1 1/4
mm   647.7 57.2 469.9 482.6 406.4 146.1 12.7 571.5 35.1   31.8
in 18 28.00 2.38 21.00 21.00 18.00 6.25  1/2 24.75 1.38 24 1 1/4
mm   711.2 60.5 533.4 533.4 457.2 158.8 12.7 628.7 35.1   31.8
in 20 30.50 2.50 23.00 23.12 20.00 6.38  1/2 27.00 1.38 24 1 1/4
mm   774.7 63.5 584.2 587.2 508.0 162.1 12.7 685.8 35.1   31.8
in 24 36.00 2.75 27.25 27.62 24.00 6.62  1/2 32.00 1.62 24 1 1/2
mm   914.4 69.9 692.2 701.5 609.6 168.1 12.7 812.8 41.1   38.1
Note:  Weld Neck flanges NPS 3" and smaller are identical to Class 600 flanges and may be so marked.
(1)  Bore diameter to be specified by purchaser.
(2)  Other NPT and SW connections available upon request.

Welding Neck Orifice Class 300 Flange PDF (for printing).