ASME B16.47 Series A class 900 flange: dimensions and bolt pattern
Large-diameter flanges, NPS 26 to 48, weld neck (WN) and blind. Series A (formerly MSS SP-44) has more robust flanges, with fewer, larger-diameter bolts. It is the most used in process piping.
Dimensions and bolt pattern
| NPS | DN | O | tf WN | tf blind | X | Ah | Y | W | Holes | Hole Ø | Bolt | WN weight* | Blind weight* |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 26" | 650 | 1085.8 | 139.7 | 160.3 | 774.7 | 660.4 | 285.8 | 952.5 | 20 | 73.0 | 2¾" | 664 | 1060 |
| 28" | 700 | 1168.4 | 142.7 | 171.5 | 831.9 | 711.2 | 298.4 | 1022.4 | 20 | 76.2 | 2⅞" | 790 | 1321 |
| 30" | 750 | 1231.9 | 149.4 | 182.4 | 889.0 | 762.0 | 311.2 | 1085.8 | 20 | 76.2 | 2⅞" | 913 | 1576 |
| 32" | 800 | 1314.5 | 158.8 | 193.5 | 946.1 | 812.8 | 330.2 | 1155.7 | 20 | 85.7 | 3¼" | 1084 | 1886 |
| 34" | 850 | 1397.0 | 165.1 | 204.7 | 1006.3 | 863.6 | 349.3 | 1225.6 | 20 | 92.1 | 3½" | 1272 | 2249 |
| 36" | 900 | 1460.5 | 171.5 | 214.4 | 1063.8 | 914.4 | 361.9 | 1289.1 | 20 | 92.1 | 3½" | 1438 | 2595 |
| 38" | 950 | 1460.5 | 190.5 | 215.9 | 1073.2 | 965.2 | 352.6 | 1289.1 | 20 | 92.1 | 3½" | 1399 | 2614 |
| 40" | 1000 | 1511.3 | 196.8 | 223.8 | 1127.3 | 1016.0 | 363.5 | 1339.9 | 24 | 92.1 | 3½" | 1478 | 2871 |
| 42" | 1050 | 1562.1 | 206.2* | 231.6 | 1176.3 | 1066.8 | 371.3 | 1390.7 | 24 | 92.1 | 3½" | 1612 | 3194 |
| 44" | 1100 | 1648.0 | 214.4 | 242.8 | 1234.9 | 1117.6 | 390.7 | 1463.5 | 24 | 98.4 | 3¾" | 1881 | 3718 |
| 46" | 1150 | 1733.6 | 225.6 | 255.5 | 1292.4 | 1168.4 | 411.0 | 1536.7 | 24 | 104.8 | 4" | 2198 | 4319 |
| 48" | 1200 | 1784.4 | 233.4 | 263.7 | 1343.2 | 1219.2 | 419.1 | 1587.5 | 24 | 104.8 | 4" | 2362 | 4748 |
O = outside diameter · tf = thickness (without raised face) · X = hub at base · Ah = diameter at bevel · Y = overall length of the WN · W = bolt circle. Weight estimated in carbon steel with STD wall bore; stainless ≈ +1 %, nickel alloys +7 % to +13 %.
Allowable pressure of class 900 (bar)
| Material (group) | −29 to 38 °C | 100 °C | 200 °C | 300 °C | 400 °C |
|---|---|---|---|---|---|
| Carbon steel A105 / A350 LF2 (1.1) | 153.2 | 139.8 | 131.4 | 119.5 | 104.2 |
| Stainless F304 / F304H (2.1) | 148.9 | 122.6 | 103.4 | 92.7 | 85.3 |
| Stainless F316 / F316H (2.2) | 148.9 | 126.6 | 107.0 | 94.9 | 88.3 |
| Duplex F51, super duplex F53 / F55 (up to 315 °C), 6Mo F44 (2.8) | 155.1 | 152.0 | 128.0 | 116.6 | 109.8 |
| Inconel 625, Incoloy 825, Hastelloy C-276 / C-22 (3.8) | 155.1 | 154.6 | 145.0 | 128.6 | 109.8 |
ASME B16.47 uses the same pressure classes as B16.5. "–" = material outside the temperature range.
Frequently asked questions
What is the difference between Series A and Series B of ASME B16.47?
Both cover NPS 26 to 60, but they are not interchangeable: outside diameter, bolt circle and number of bolts are different. Series A is more robust (formerly MSS SP-44); Series B is more compact (formerly API 605). Check the series on the drawing before buying.
When to use ASME B16.47 instead of B16.5?
ASME B16.5 goes up to NPS 24. From NPS 26 to 60, ASME B16.47 applies, in Series A or B.
What is the pressure of a B16.47 class 900 flange?
The pressure class follows the same tables as ASME B16.5. In A105 carbon steel, class 900 allows 153.2 bar from −29 to 38 °C.
