ANSI B16.36 FORGED FLANGES  Unit: mm
Class 400 Orifice Flanges
Nominal Pipe Size Outside Diam of Flange Thickness of Flange (1) Diam of Hub at base  Diam of raised face Diam of Hub Bevel Length thru Hub (1) Bore (B) Pitch Diam of Ring and Groove Ring Number Depth of jack screw slot Depth of jack screw slot Drilling Template Nominal Pipe Size
Raised Face Ring Joint Welding Neck Slip- on & threaded Welding Neck Slip- on  Raised face Ring Joint Raised face Ring Joint Diam of bolt circle Number of Bolts Diam. Of Stud Bolts (inch) Diam. Of Bolt Holes Length of stud bolts
D X G A Raised Face Ring joint Raised Face Ring joint P Raised face Ring Joint
1 124 38.1 31.8 53.8 50.8 35.5 82.6 76.2 47.8 41.1 See Note (1) to be specified by purchaser 34.5 50.8 R16 9.7 6.4 5/8×4.00 5/8×4.75 88.9 4  5/8 17.5 127.0 146.1 1
1 ¼  133 38.1 31.8 63.5 63.5 42.2 84.1 77.7 46.0 39.6 43.2 60.3 R18 9.7 6.4 5/8×4.00 5/8×4.75 98.6 4  5/8 17.5 127.0 120.7 1 ¼ 
1 ½  155 38.1 31.8 69.9 73.2 48.3 85.9 79.2 47.8 41.1 49.5 68.3 R20 12.7 6.4 ¾×4.25 ¾×5.00 114.3 4  3/4 21.0 133.4 152.4 1 ½ 
2 165 38.1 31.8 84.1 91.9 60.5 85.9 79.2 49.3 42.9 62.0 82.6 R23 9.7 6.4 5/8×4.00 5/8×4.75 127.0 8  5/8 17.5 127.0 152.4 2
2 ½  191 38.1 31.8 100.1 104.6 73.2 88.9 82.6 50.8 44.5 74.7 101.6 R26 12.7 6.4 ¾×4.25 ¾×5.00 149.4 8  3/4 20.6 133.4 158.8 2 ½ 
3 210 38.1 31.8 117.3 127.0 88.9 88.9 82.6 52.3 46.0 90.7 123.8 R31 12.7 6.4 ¾×4.25 ¾×5.00 168.1 8  3/4 20.6 133.4 158.8 3
4 254 35.1 35.1 146.1 157.2 114.3 88.9 88.9 50.8 50.8 116.1 149.2 R37 6.4 15.7 ¾×3.00 ¾×4.00 200.2 8  7/8 25.4 139.7 152.4 4
5 279 38.1 38.1 177.8 185.7 141.2 101.6 101.6 53.8 53.8 143.8 181.0 R41 6.4 15.7 ¾×3.00 ¾×4.00 235.0 8  7/8 25.4 146.1 158.8 5
6 318 41.1 41.1 206.2 215.9 168.4 103.1 103.1 57.2 57.2 170.7 211.1 R45 12.7 22.4 1×3.50 1×4.00 269.7 12  7/8 25.4 158.8 165.1 6
8 381 47.8 47.8 260.4 269.7 219.2 117.3 117.3 68.3 68.3 221.5 269.9 R49 12.7 22.4 1×3.50 1×4.50 330.2 12 1 28.4 171.5 184.2 8
10 445 53.8 53.8 320.5 323.9 273.1 124.0 124.0 73.2 73.2 276.4 323.9 R53 12.7 22.4 1×4.00 1×4.50 387.4 16 1 1/8 31.8 190.5 203.2 10
12 521 57.2 57.2 374.7 381.0 323.9 136.7 136.7 79.2 79.2 327.2 381.0 R57 12.7 22.4 1×4.00 1×5.00 450.9 16 1 ¼ 35.1 203.2 215.9 12
14 584 60.7 60.7 425.5 412.8 355.6 149.4 149.4   359.2 419.1 R61 12.7 22.4 1×4.25 1×5.00 514.4 20 1 ¼ 35.1 209.6 228.6 14
16 648 63.5 63.5 482.6 469.9 406.4 152.4 152.4 410.5 469.9 R65 12.7 22.4 1×4.25 1×5.00 571.5 20 1 3/8 38.1 222.3 235.0 16
18 711 66.5 66.5 533.4 533.4 457.2 165.1 165.1 461.8 533.4 R69 12.7 22.4 1×4.50 1×5.00 628.7 24 1 3/8 38.1 235.0 241.3 18
20 775 69.9 69.9 587.2 584.2 508.0 168.1 168.1 513.1 584.2 R73 12.7 22.4 1×4.75 1×5.50 685.8 24 1 ½ 41.1 247.7 260.4 20
24 914 76.2 76.2 701.5 692.2 609.6 174.8 174.8 564.4 692.2 R77 12.7 22.4 1×5.00 1×6.00 812.8 24 1 ¾ 47.8 279.4 285.8 24
Notes:
(1) For the inside diameter of Pipes (corresponding to Bore (B) of welding Neck Flanges), refer to 54.
(2) Class 400 flanges of size 3" and smaller will be furnished with 0.06" (1.6mm) raised face, which is included in 
thickness (t) and length through Hub (T)
The 0.25" (6.35mm) raised face for sizes 4" and larger is not included in (t) and (T)
(3) Each union includes two carbon steel jack screw bolts with hex nuts.
(4) Unless otherwise specified, raised face union are furnished with alloy bolt studs per ASTM A193 Grade B7 with American.
Standard heavy series hex nuts ASTM A197 Class 2H.
(5) On ring joint flanges having a groove depth 0.375" (9.5mm) and less, the distance from the center line of the tap hole to the flange
face is 0.750" (19.1mm) when the depth of groove is 0.438" (11.1mm) or greater, changes in drill size or method of drilling are necessary.
(6) Bolt lengths for raised face flanges include allowance for orifice and gasket thickness of 0.25" (6.4mm) for sizes 4-12 and 
0.38" (9.7mm) for sizes 14-24. bolt lengths for ring type joint flanges include allowance of 0.62" (15.7mm) for sizes 4-10
0.75" (19.1mm) for sizes 12-18 and 0.88" (22.4mm) for size 20.