Pressure-Temperature Ratings for Inconel Alloy 625 Flanges
Inconel alloy 625 flanges manufactured to ASME B16.5 fall into the Group 3.8 materials of the standard specification. They can be supplied in 7 classes: 150, 300, 400, 600, 900, 1500, 2500. Flanges with hub, such as weld neck, slip on, threaded, socket weld, and LWN, are made in accordance with ASTM B564 Gr.N06625; flanges without hub, such as blind or flat, can be either made from ASTM B564 Gr.N06625 forgings or ASTM B443 Gr.N06625 plates.
The Inconel alloy 625 flange shall always be furnished in annealed condition. Since alloy 625 in the annealed condition is subject to severe loss of impact strength at room temperatures after exposure in the range of 538°C to 760°C， it shall not be used over 645°C. The typical pressure-temperature ratings for Inconel alloy 625 pipe flanges are listed in below tables.
Pressure-Temperature Rating for Alloy 625 flanges Class 150 & 300
| Temp. | Working Pressures by Classes | |
| Class 150 | Class 300 | |
| -29 to 38 | 20.0 | 51.7 |
| 50 | 19.5 | 51.7 |
| 100 | 17.7 | 51.5 |
| 150 | 15.8 | 50.3 |
| 200 | 13.8 | 48.3 |
| 250 | 12.1 | 46.3 |
| 300 | 10.2 | 42.9 |
| 325 | 9.3 | 41.4 |
| 350 | 8.4 | 40.3 |
| 375 | 7.4 | 38.9 |
| 400 | 6.5 | 36.5 |
| 425 | 5.5 | 35.2 |
| 450 | 4.6 | 33.7 |
| 475 | 3.7 | 31.7 |
| 500 | 2.8 | 28.2 |
| 538 | 1.4 | 25.2 |
| 550 | . . . | 25.0 |
| 575 | . . . | 24.0 |
| 600 | . . . | 21.6 |
| 625 | . . . | 18.3 |
| 650 | . . . | 14.1 |
| 675 | . . . | 11.5 |
| 700 | . . . | 8.8 |
Pressure-Temperature Rating for Alloy 625 flanges Class 600 & 900
| Temp. | Working Pressures by Classes | |
| Class 600 | Class 900 | |
| -29 to 38 | 103.4 | 155.1 |
| 50 | 103.4 | 155.1 |
| 100 | 103.0 | 154.6 |
| 150 | 100.3 | 150.6 |
| 200 | 96.7 | 145.0 |
| 250 | 92.7 | 139.0 |
| 300 | 85.7 | 128.6 |
| 325 | 82.6 | 124.0 |
| 350 | 80.4 | 120.7 |
| 375 | 77.6 | 116.5 |
| 400 | 73.3 | 109.8 |
| 425 | 70.0 | 105.1 |
| 450 | 67.7 | 101.4 |
| 475 | 63.4 | 95.1 |
| 500 | 56.5 | 84.7 |
| 538 | 50.0 | 75.2 |
| 550 | 49.8 | 74.8 |
| 575 | 47.9 | 71.8 |
| 600 | 42.9 | 64.2 |
| 625 | 36.6 | 54.9 |
| 650 | 28.1 | 42.2 |
| 675 | 23.0 | 34.6 |
| 700 | 17.5 | 26.3 |
Pressure-Temperature Rating for Alloy 625 flanges Class 1500 & 2500
| Temp. | Working Pressures by Classes | |
| Class 1500 | Class 2500 | |
| -29 to 38 | 258.6 | 430.9 |
| 50 | 258.6 | 430.9 |
| 100 | 257.6 | 429.4 |
| 150 | 250.8 | 418.2 |
| 200 | 241.7 | 402.8 |
| 250 | 231.8 | 386.2 |
| 300 | 214.4 | 357.1 |
| 325 | 206.6 | 344.3 |
| 350 | 201.1 | 335.3 |
| 375 | 194.1 | 323.2 |
| 400 | 183.1 | 304.9 |
| 425 | 175.1 | 291.6 |
| 450 | 169.0 | 281.8 |
| 475 | 158.2 | 263.9 |
| 500 | 140.9 | 235.0 |
| 538 | 125.5 | 208.9 |
| 550 | 124.9 | 208.0 |
| 575 | 119.7 | 199.5 |
| 600 | 107.0 | 178.5 |
| 625 | 91.2 | 152.0 |
| 650 | 70.4 | 117.3 |
| 675 | 57.6 | 96.0 |
| 700 | 43.8 | 73.0 |
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