All dimensions are in "mm" unless noted otherwise.
Dimensions of Class 900 Ring Joint (RTJ) Flanges as per ASME B16.5.

| Nominal Pipe Size (inches) |
Pitch Dia of Ring and Groove |
Width of Ring | Height of Ring | Width of Flat on Octagonal Rings |
Width of Groove | Depth of Groove | Dia of Raised Face |
Ring Number | Approx. gap between flanges after gasket compression |
|
|---|---|---|---|---|---|---|---|---|---|---|
| Oval | Octagonal | |||||||||
| P | A | B | H | C | F | E | K (min) | X | ||
| 1/2 | 39.67 | 8.0 | 14.3 | 12.7 | 5.2 | 8.7 | 6.4 | 60.5 | R12 | 4.1 |
| 3/4 | 44.45 | 8.0 | 14.3 | 12.7 | 5.2 | 8.7 | 6.4 | 66.8 | R14 | 4.1 |
| 1 | 50.80 | 8.0 | 14.3 | 12.7 | 5.2 | 8.7 | 6.4 | 71.4 | R16 | 4.1 |
| 1-1/4 | 60.33 | 8.0 | 14.3 | 12.7 | 5.2 | 8.7 | 6.4 | 81.0 | R18 | 4.1 |
| 1-1/2 | 68.28 | 8.0 | 14.3 | 12.7 | 5.2 | 8.7 | 6.4 | 92.2 | R20 | 4.1 |
| 2 | 95.25 | 11.1 | 17.5 | 15.9 | 7.7 | 11.9 | 7.9 | 124.0 | R24 | 3.0 |
| 2-1/2 | 107.95 | 11.1 | 17.5 | 15.9 | 7.7 | 11.9 | 7.9 | 136.7 | R27 | 3.0 |
| 3 | 123.82 | 11.1 | 17.5 | 15.9 | 7.7 | 11.9 | 7.9 | 155.4 | R31 | 4.1 |
| 4 | 149.22 | 11.1 | 17.5 | 15.9 | 7.7 | 11.9 | 7.9 | 180.8 | R37 | 4.1 |
| 5 | 180.98 | 11.1 | 17.5 | 15.9 | 7.7 | 11.9 | 7.9 | 215.9 | R41 | 4.1 |
| 6 | 211.12 | 11.1 | 17.5 | 15.9 | 7.7 | 11.9 | 7.9 | 241.3 | R45 | 4.1 |
| 8 | 269.88 | 11.1 | 17.5 | 15.9 | 7.7 | 11.9 | 7.9 | 307.8 | R49 | 4.1 |
| 10 | 323.85 | 11.1 | 17.5 | 15.9 | 7.7 | 11.9 | 7.9 | 362.0 | R53 | 4.1 |
| 12 | 381.00 | 11.1 | 17.5 | 15.9 | 7.7 | 11.9 | 7.9 | 419.10 | R57 | 4.1 |
| 14 | 419.10 | 15.9 | 22.2 | 20.7 | 10.5 | 16.7 | 11.1 | 466.9 | R62 | 4.1 |
| 16 | 469.90 | 15.9 | 22.2 | 20.7 | 10.5 | 16.7 | 11.1 | 523.7 | R66 | 4.1 |
| 18 | 533.40 | 19.1 | 25.4 | 23.8 | 11.1 | 19.8 | 12.7 | 593.9 | R70 | 4.8 |
| 20 | 584.20 | 19.1 | 25.4 | 23.8 | 12.3 | 19.8 | 12.7 | 647.7 | R74 | 4.8 |
| 24 | 692.15 | 25.4 | 33.4 | 31.8 | 17.3 | 27.0 | 15.9 | 771.7 | R78 | 5.6 |