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Dimensions of Non-Metallic Flat Gaskets ASME B16.21
CLASS 150 TO 900 NPS 1/2 TO 24
NPS d1 d2
Class 150 Class 300 Class 400 Class 600 Class 900
1/2 21 48 54 54 54 64
3/4 27 57 67 67 67 70
1 33 67 73 73 73 79
42 76 83 83 83 89
48 86 95 95 95 98
2 60 105 111 111 111 143
73 124 130 130 130.2 165
3 89 137 149 149 149 168
102 162 165 162 162 ...
4 114 175 181 178 194 206
5 141 197 216 213 241 248
6 168 222 251 248 267 289
8 219 279 308 305 321 359
10 273 340 362 359 400 435
12 324 410 422 419 457 498
14 356 451 486 483 492 521
16 406 514 540 537 565 575
18 457 549 597 594 613 638
20 508 606 654 648 683 699
24 610 718 775 768 791 838
NPS d1 Class 150 Class 300 Class 400 Class 600 Class 900
d2

General notes:

 

 Dimensions are in millimeters unless otherwise indicated.

 d1 = Inside diameter.

 d2 = Outside diameter.

 Dimensional tolerances outside diameter NPS 12 and smaller: +0 / -1.5 mm.

 Dimensional tolerances outside diameter NPS 14 and larger: +0 / -3.0 mm.

 Dimensional tolerances inside diameter NPS 12 and smaller: ± 1.5 mm.

 Dimensional tolerances inside diameter NPS 14 and larger: ± 3.0 mm.

 Thickness (t) specified by customer.