IS-1538
Standard Flange Drilling as IS 1538
Nominal
Diameter DN		 OD ID Thickness Holes PCD
Number A Diameter d
mm mm mm mm   mm  
80 200 91 21 4 19 160
100 220 117 22 8 19 180
125 250 144 22.5 8 19 210
150 285 171 23 8 23 240
200 340 222 24.5 8 23 295
250 395 277 26 12 23 350
300 445 327 27.5 12 23 400
350 505 359 29 16 23 460
400 565 411 30 16 28 515
450 615 462 31.5 20 28 565
500 670 513 33 20 28 620
600 780 616 36 20 31 725
700 895 716 38.5 24 31 110
750 960 765 40 24 31 117.7
800 1015 819 41.5 24 34 950
900 1115 920 44 28 34 1050
1000 1230 1020 47 28 37 1160
1100 1340 1124   32 37 124.6
1200 1455 1223 50 32 40 1380
1500 1800 1530 53 40 43 1710
1800 2100 1832   48 46 200

PCD x 3.14 / No of holes = Center

American Standard

British Standard

German Standard

BS EN 1092-1:2002

Indian Standard