Standard: ASME B16.47-2020 | Sizes: NPS 26" to 60" | Class 150 / 300 / 400 / 600 / 900 | Units: inch / mm
ASME B16.47 covers large-diameter steel flanges from NPS 26 to NPS 60 (DN 650 to DN 1500). It is published by ASME International and applies to petroleum refinery, chemical processing, and power plant piping systems where pipe sizes exceed the NPS 24 limit of ASME B16.5.
The standard defines two flange series: Series A (based on MSS SP-44, larger outside diameter) and Series B (based on API 605, slightly smaller dimensions). Both series are dimensionally distinct — always verify which series is specified in your project documentation. Series A is more commonly specified in modern projects.
Series A vs Series B: Series A (MSS SP-44) flanges have larger outside diameters than Series B (API 605). The bolt circle diameters (W) also differ. Always confirm the applicable series from project specifications — mixing Series A and B components can cause assembly problems due to different bolt circle diameters.
Series A (MSS SP-44) — Class 150 ASME B16.47
NPS 26 – 48 (DN 650 – 1200)
NPS
(in) |
DN
(mm) |
O
(mm) |
C
(mm) |
R
(mm) |
W
(mm) |
dh
(mm) |
n |
Bolt
Size |
Weight
(kg, CS) |
| 26 |
650 |
1030 |
38.1 |
927 |
977 |
34.9 |
28 |
1¼ |
580 |
| 28 |
700 |
1110 |
41.3 |
984 |
1054 |
34.9 |
28 |
1¼ |
720 |
| 30 |
750 |
1170 |
41.3 |
1041 |
1114 |
34.9 |
28 |
1¼ |
810 |
| 32 |
800 |
1230 |
44.5 |
1092 |
1170 |
41.3 |
28 |
1½ |
960 |
| 34 |
850 |
1290 |
44.5 |
1149 |
1230 |
41.3 |
32 |
1½ |
1070 |
| 36 |
900 |
1350 |
47.7 |
1200 |
1286 |
41.3 |
32 |
1½ |
1240 |
| 38 |
950 |
1410 |
47.7 |
1262 |
1346 |
41.3 |
32 |
1½ |
1360 |
| 40 |
1000 |
1470 |
47.7 |
1319 |
1406 |
41.3 |
36 |
1½ |
1470 |
| 42 |
1050 |
1530 |
50.8 |
1372 |
1466 |
41.3 |
36 |
1½ |
1700 |
| 44 |
1100 |
1590 |
50.8 |
1429 |
1524 |
47.7 |
36 |
1¾ |
1830 |
| 46 |
1150 |
1650 |
53.9 |
1486 |
1584 |
47.7 |
40 |
1¾ |
2090 |
| 48 |
1200 |
1710 |
53.9 |
1543 |
1644 |
47.7 |
40 |
1¾ |
2250 |
| 50 |
1250 |
1770 |
57.2 |
1600 |
1702 |
47.7 |
44 |
1¾ |
2560 |
| 52 |
1300 |
1830 |
57.2 |
1657 |
1762 |
47.7 |
44 |
1¾ |
2740 |
| 54 |
1350 |
1890 |
57.2 |
1714 |
1822 |
47.7 |
44 |
1¾ |
2920 |
| 56 |
1400 |
1950 |
60.3 |
1772 |
1882 |
54.0 |
44 |
2 |
3280 |
| 58 |
1450 |
2010 |
60.3 |
1829 |
1942 |
54.0 |
48 |
2 |
3470 |
| 60 |
1500 |
2070 |
60.3 |
1886 |
2002 |
54.0 |
48 |
2 |
3690 |
Series B (API 605) — Class 150 ASME B16.47
Series B (API 605): Has smaller outside diameters than Series A. The bolt circle diameters are also different. Series B flanges are generally lighter than Series A at the same size. Note: API 605 has been formally withdrawn and replaced; however, Series B dimensions remain in ASME B16.47 for legacy compatibility.
NPS 26 – 48 (DN 650 – 1200) — Key Sizes
NPS
(in) |
DN
(mm) |
O
(mm) |
C
(mm) |
R
(mm) |
W
(mm) |
dh
(mm) |
n |
Bolt
Size |
Weight
(kg, CS) |
| 26 |
650 |
990 |
34.9 |
914 |
950 |
31.8 |
24 |
1⅛ |
490 |
| 28 |
700 |
1055 |
34.9 |
965 |
1016 |
31.8 |
28 |
1⅛ |
555 |
| 30 |
750 |
1110 |
38.1 |
1016 |
1067 |
34.9 |
28 |
1¼ |
665 |
| 32 |
800 |
1170 |
38.1 |
1067 |
1124 |
34.9 |
28 |
1¼ |
740 |
| 34 |
850 |
1230 |
38.1 |
1118 |
1181 |
34.9 |
32 |
1¼ |
820 |
| 36 |
900 |
1290 |
38.1 |
1168 |
1232 |
38.1 |
32 |
1⅜ |
910 |
| 38 |
950 |
1350 |
38.1 |
1219 |
1292 |
38.1 |
32 |
1⅜ |
990 |
| 40 |
1000 |
1410 |
38.1 |
1270 |
1343 |
38.1 |
36 |
1⅜ |
1080 |
| 42 |
1050 |
1470 |
38.1 |
1321 |
1403 |
38.1 |
36 |
1⅜ |
1175 |
| 44 |
1100 |
1530 |
41.3 |
1372 |
1454 |
41.3 |
40 |
1½ |
1385 |
| 46 |
1150 |
1590 |
41.3 |
1422 |
1510 |
41.3 |
40 |
1½ |
1490 |
| 48 |
1200 |
1650 |
41.3 |
1473 |
1568 |
41.3 |
40 |
1½ |
1600 |
Series A Class 300 / 400 / 600 — Key Dimensions ASME B16.47
Class 300+ Dimensions: Class 300, 400, and 600 dimensions for Series A (NPS 26–60) share the same basic OD as Class 150 but have progressively thicker flanges and larger bolt circles. Full tables available on request or from the ASME B16.47-2020 standard. Contact HT PIPE for specific Class 300–600 dimension datasheets.
NPS
(in) |
DN
(mm) |
Class 150
O / C (mm) |
Class 300
O / C (mm) |
Class 400
O / C (mm) |
Class 600
O / C (mm) |
Bolt
Circle W
(mm) |
| 26 |
650 |
1030 |
38.1 |
1080 |
50.8 |
1110 |
53.9 |
1130 |
63.5 |
977 |
| 28 |
700 |
1110 |
41.3 |
1150 |
53.9 |
1180 |
57.2 |
1200 |
66.7 |
1054 |
| 30 |
750 |
1170 |
41.3 |
1230 |
57.2 |
1250 |
60.3 |
1280 |
69.9 |
1114 |
| 32 |
800 |
1230 |
44.5 |
1290 |
60.3 |
1320 |
63.5 |
1350 |
73.1 |
1170 |
| 34 |
850 |
1290 |
44.5 |
1350 |
63.5 |
1380 |
66.7 |
1410 |
76.2 |
1230 |
| 36 |
900 |
1350 |
47.7 |
1410 |
66.7 |
1450 |
69.9 |
1470 |
79.4 |
1286 |
| 38 |
950 |
1410 |
47.7 |
1470 |
69.9 |
1510 |
73.1 |
1540 |
82.6 |
1346 |
| 40 |
1000 |
1470 |
47.7 |
1530 |
73.1 |
1570 |
76.2 |
1600 |
85.8 |
1406 |
| 42 |
1050 |
1530 |
50.8 |
1590 |
76.2 |
1630 |
79.4 |
1660 |
88.9 |
1466 |
| 44 |
1100 |
1590 |
50.8 |
1650 |
79.4 |
1690 |
82.6 |
1720 |
92.1 |
1524 |
| 46 |
1150 |
1650 |
53.9 |
1710 |
82.6 |
1750 |
85.8 |
1790 |
95.3 |
1584 |
| 48 |
1200 |
1710 |
53.9 |
1770 |
85.8 |
1810 |
88.9 |
1850 |
98.5 |
1644 |
| 50 |
1250 |
1770 |
57.2 |
1830 |
88.9 |
1870 |
92.1 |
1910 |
101.6 |
1702 |
| 52 |
1300 |
1830 |
57.2 |
1890 |
92.1 |
1930 |
95.3 |
1970 |
104.8 |
1762 |
| 54 |
1350 |
1890 |
57.2 |
1950 |
95.3 |
1990 |
98.5 |
2030 |
108.0 |
1822 |
| 56 |
1400 |
1950 |
60.3 |
2010 |
98.5 |
2050 |
101.6 |
2090 |
111.2 |
1882 |
| 58 |
1450 |
2010 |
60.3 |
2070 |
101.6 |
2110 |
104.8 |
2150 |
114.3 |
1942 |
| 60 |
1500 |
2070 |
60.3 |
2130 |
104.8 |
2170 |
108.0 |
2210 |
117.5 |
2002 |
ASME B16.5 vs ASME B16.47 — Key Differences
| Parameter |
ASME B16.5 |
ASME B16.47 |
| Size Range |
NPS ½ – 24 (DN 15 – 600) |
NPS 26 – 60 (DN 650 – 1500) |
| Standard Basis |
Original ASME flange standard |
B16.47 includes both Series A (MSS SP-44) and Series B (API 605) |
| Pressure Classes |
150, 300, 400, 600, 900, 1500, 2500 |
150, 300, 400, 600, 900 |
| Face Types |
RF, FF, RTJ, TG |
RF (Raised Face), RTJ (Ring Type Joint) |
| Typical Application |
General industrial, chemical, oil & gas |
Large refinery, petrochemical, power plants, offshore platforms |
| Forgings vs Plates |
Mostly forged; some castings for large sizes |
Often fabricated from plate for sizes ≥ NPS 26; some forged options |
| Weight |
Lower for same Class/DN in B16.5 |
Heavier due to larger OD and thickness for structural reasons |
When to use ASME B16.47: Use B16.47 for all piping systems with nominal pipe sizes NPS 26 and above. The standard is mandatory in API 650 storage tank nozzle design, most refinery tie-in specifications, and power plant projects per ASME Section III or Section I. Always confirm project specifications — some projects require B16.47 even for NPS 24 and below.
Reference Standard: ASME B16.47-2020 — Large Diameter Steel Flanges (NPS 26 Through NPS 60). Published by ASME International. © ASME. Series A dimensions based on MSS SP-44; Series B dimensions based on API 605 (withdrawn but retained for legacy compatibility).
Disclaimer: Data shown is for reference only. Verify against ASME B16.47-2020 and applicable project specifications. HT PIPE assumes no liability for the use of this data.
