Pipe flanges · ASME
Large-diameter pipe flanges to ASME B16.47: series A and B
ASME B16.47 series A and BNPS 26–60Dimensions in mm and incheson request
Choose a size
How to use the selection
Choose series and class, then NPS – the result shows the connection dimensions in mm with inches in brackets. Series A and series B have different bolt patterns.
Dimension table ASME B16.47
Show full table · more than 20 rows
| NPS | Series · class | O mm (in) | tf WN mm (in) | tf BL mm (in) | C mm (in) | W mm (in) | K mm (in) | Y1 mm (in) | n × hole mm (in) | Bolt | Kind of value | Availability |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 26" | A · 150 | 869.9 (34.25) | 66.8 (2.63) | 806.4 (31.75) | 24 × 35.1 (1.38) | 1.25 in | market dimension | available on request | ||||
| 30" | A · 150 | 984.2 (38.75) | 73.2 (2.88) | 73.2 (2.88) | 914.4 (36) | 781.0 (30.75) | 762.0 (30) | 135.1 (5.32) | 28 × 34.9 (1.375) | 1.25 in | market dimension | available on request |
| 36" | A · 150 | 1168.4 (46) | 88.9 (3.5) | 88.9 (3.5) | 1085.8 (42.75) | 933.4 (36.75) | 914.4 (36) | 155.7 (6.13) | 32 × 41.3 (1.625) | 1.5 in | market dimension | available on request |
| 42" | A · 150 | 1346.2 (53) | 95.2 (3.75) | 95.2 (3.75) | 1257.3 (49.5) | 1092.2 (43) | 1066.8 (42) | 169.9 (6.69) | 36 × 41.3 (1.625) | 1.5 in | market dimension | available on request |
| 48" | A · 150 | 1511.3 (59.5) | 106.4 (4.19) | 106.4 (4.19) | 1422.4 (56) | 1247.6 (49.12) | 1219.2 (48) | 190.5 (7.5) | 44 × 41.3 (1.625) | 1.5 in | market dimension | available on request |
| 60" | A · 150 | 1854.2 (73) | 130.3 (5.13) | 1758.9 (69.25) | 52 × 47.8 (1.88) | 1.75 in | market dimension | available on request | ||||
| 30" | A · 300 | 1092.2 (43) | 90.7 (3.57) | 93.7 (3.69) | 996.9 (39.25) | 827.0 (32.56) | 762.0 (30) | 208.0 (8.19) | 28 × 47.6 (1.875) | 1.75 in | market dimension | available on request |
| 36" | A · 300 | 1270.0 (50) | 103.4 (4.07) | 109.7 (4.32) | 1168.4 (46) | 990.6 (39) | 914.4 (36) | 239.8 (9.44) | 32 × 54.0 (2.125) | 2 in | market dimension | available on request |
| 42" | A · 300 | 1289.0 (50.75) | 117.6 (4.63) | 117.6 (4.63) | 1206.5 (47.5) | 1098.5 (43.25) | 1066.8 (42) | 198.6 (7.82) | 32 × 44.4 (1.75) | 1.625 in | market dimension | available on request |
| 48" | A · 300 | 1466.8 (57.75) | 131.8 (5.19) | 131.8 (5.19) | 1371.6 (54) | 1254.3 (49.38) | 1219.2 (48) | 222.2 (8.75) | 32 × 50.8 (2) | 1.875 in | market dimension | available on request |
| 30" | A · 600 | 1130.3 (44.5) | 114.3 (4.5) | 139.7 (5.5) | 1022.3 (40.25) | 862.1 (33.94) | 762.0 (30) | 247.6 (9.75) | 28 × 54.0 (2.125) | 2 in | market dimension | available on request |
| 36" | A · 600 | 1314.4 (51.75) | 124.0 (4.88) | 162.1 (6.38) | 1193.8 (47) | 1031.7 (40.62) | 914.4 (36) | 282.4 (11.12) | 28 × 66.7 (2.625) | 2.5 in | market dimension | available on request |
| 42" | A · 600 | 1403.3 (55.25) | 168.1 (6.62) | 171.4 (6.75) | 1282.7 (50.5) | 1127.3 (44.38) | 1066.8 (42) | 279.4 (11) | 28 × 66.7 (2.625) | 2.5 in | market dimension | available on request |
| 48" | A · 600 | 1593.8 (62.75) | 189.0 (7.44) | 195.3 (7.69) | 1460.5 (57.5) | 1289.0 (50.75) | 1219.2 (48) | 316.0 (12.44) | 32 × 73.0 (2.875) | 2.75 in | market dimension | available on request |
| 30" | A · 900 | 1231.9 (48.5) | 149.4 (5.88) | 182.4 (7.18) | 1085.8 (42.75) | 889.0 (35) | 762.0 (30) | 311.1 (12.25) | 20 × 79.4 (3.125) | 3 in | market dimension | available on request |
| 36" | A · 900 | 1460.5 (57.5) | 171.4 (6.75) | 214.4 (8.44) | 1289.0 (50.75) | 1063.8 (41.88) | 914.4 (36) | 361.9 (14.25) | 20 × 92.1 (3.625) | 3.5 in | market dimension | available on request |
| 42" | A · 900 | 1562.1 (61.5) | 206.2 (8.12) | 231.6 (9.12) | 1390.6 (54.75) | 1176.3 (46.31) | 1066.8 (42) | 371.3 (14.62) | 24 × 92.1 (3.625) | 3.5 in | market dimension | available on request |
| 48" | A · 900 | 1784.3 (70.25) | 233.4 (9.19) | 263.7 (10.38) | 1587.5 (62.5) | 1343.2 (52.88) | 1219.2 (48) | 419.1 (16.5) | 24 × 104.8 (4.125) | 4 in | market dimension | available on request |
| 30" | B · 150 | 887.5 (34.94) | 42.9 (1.69) | 49.3 (1.94) | 846.1 (33.31) | 787.4 (31) | 763.5 (30.06) | 98.6 (3.88) | 44 × 22.2 (0.875) | 0.75 in | market dimension | available on request |
| 36" | B · 150 | 1057.1 (41.62) | 50.8 (2) | 57.1 (2.25) | 1009.6 (39.75) | 944.6 (37.19) | 915.9 (36.06) | 116.1 (4.57) | 44 × 25.4 (1) | 0.875 in | market dimension | available on request |
| 42" | B · 150 | 1225.5 (48.25) | 57.1 (2.25) | 67.3 (2.65) | 1171.4 (46.12) | 1101.9 (43.38) | 1069.8 (42.12) | 131.8 (5.19) | 48 × 28.6 (1.125) | 1 in | market dimension | available on request |
| 48" | B · 150 | 1392.2 (54.81) | 63.5 (2.5) | 76.2 (3) | 1335.0 (52.56) | 1257.3 (49.5) | 1222.2 (48.12) | 147.8 (5.82) | 44 × 31.8 (1.25) | 1.125 in | market dimension | available on request |
| 30" | B · 300 | 990.6 (39) | 92.2 (3.63) | 92.2 (3.63) | 920.8 (36.25) | 812.8 (32) | 768.3 (30.25) | 156.5 (6.16) | 36 × 38.1 (1.5) | 1.375 in | market dimension | available on request |
| 36" | B · 300 | 1171.4 (46.12) | 101.6 (4) | 101.6 (4) | 1089.2 (42.88) | 965.2 (38) | 920.8 (36.25) | 179.3 (7.06) | 32 × 44.4 (1.75) | 1.625 in | market dimension | available on request |
| 42" | B · 300 | 1333.5 (52.5) | 117.6 (4.63) | 117.6 (4.63) | 1244.6 (49) | 1117.6 (44) | 1074.7 (42.31) | 203.2 (8) | 36 × 47.6 (1.875) | 1.75 in | market dimension | available on request |
| 48" | B · 300 | 1511.3 (59.5) | 127.0 (5) | 133.3 (5.25) | 1416.0 (55.75) | 1277.9 (50.31) | 1227.1 (48.31) | 222.2 (8.75) | 40 × 50.8 (2) | 1.875 in | market dimension | available on request |
| 30" | B · 600 | 1022.3 (40.25) | 125.5 (4.94) | 127.0 (5) | 927.1 (36.5) | 806.4 (31.75) | 762.0 (30) | 204.7 (8.06) | 28 × 50.8 (2) | 1.875 in | market dimension | available on request |
| 36" | B · 600 | 1212.8 (47.75) | 146.0 (5.75) | 150.9 (5.94) | 1104.9 (43.5) | 968.2 (38.12) | 914.4 (36) | 242.8 (9.56) | 28 × 60.3 (2.375) | 2.25 in | market dimension | available on request |
| 30" | B · 900 | 1181.1 (46.5) | 155.4 (6.12) | 176.0 (6.93) | 1035.0 (40.75) | 850.9 (33.5) | 762.0 (30) | 289.1 (11.38) | 20 × 79.4 (3.125) | 3 in | market dimension | available on request |
| 36" | B · 900 | 1346.2 (53) | 173.0 (6.81) | 201.7 (7.94) | 1200.1 (47.25) | 1016.0 (40) | 914.4 (36) | 325.4 (12.81) | 24 × 79.4 (3.125) | 3 in | market dimension | available on request |
available on request – please state series, class, NPS, flange type, facing and material in the enquiry.
Flange thickness for Class 150/300 without the 1.6 mm raised face – manufacturers’ catalogues may differ here.
Tolerances: as a forging mill states them for flanges to ASME B16.47 from NPS 26 – outside diameter ±2 mm with 1.6 mm raised face (Class 150/300) and ±1 mm with 6.4 mm raised face, flange thickness only plus.
Dimensions: as the market supplies them – from manufacturers’ and suppliers’ documentation. Series A (formerly MSS SP-44) and series B (formerly API 605) are not interchangeable.
We procure large-diameter flanges to ASME B16.47 on request – the table shows the market dimensions so that you can check series and connection beforehand.
Series A or series B?
Series A is the heavier design with fewer but larger bolts; series B is lighter with more, smaller bolts. With the same class and NPS the two do not mate – an enquiry therefore always needs the series. If it is not marked on the flange, bolt circle and number of holes decide.
Pipe flanges up to NPS 24 are under pipe flange dimensions ASME B16.5, the standard in brief in the ASME B16.5 profile.
Scratches and imperfections in the gasket face – what is acceptable?
Direction comes first, depth second. A radial scratch – from the bore outwards, across the gasket face – is a continuous leak path under the gasket and is critical even when it is shallow. A concentric scratch runs with the machining grooves and is bridged by the gasket – up to about half the groove depth it is uncritical. Pits count with their radial extent, measured across the grooves. If two lie closer together than four times that extent, they count as one imperfection. Projections above the grooves are never acceptable because they lift the gasket.
For ASME pipe flanges the standard grades the acceptable size of an imperfection in the serrated gasket face by nominal pipe size. What is measured is the radial extent – across the serrations, as the difference between the outer and inner radius of the imperfection, both struck from the centre of the bore.
| NPS | Not deeper than the bottom of the serrations: radial extent up to | Deeper than the bottom of the serrations: radial extent and depth up to |
|---|---|---|
| 26–36 | 12.7 | 6.4 |
| 38–48 | 14.2 | 7.1 |
| 50–60 | 15.7 | 7.9 |
Large-diameter flanges to ASME B16.47 (NPS 26 to 60): values taken from a manufacturer reference – the check against the standard itself is still pending.
In addition
- Two imperfections must be at least four times the largest acceptable radial extent apart.
- Imperfections shallower than half the depth of the serrations are no reason for rejection.
- Projections above the serrations – a burr or raised material – are not acceptable.
- The grades apply to raised faces and large male/female faces. Ring-type joint flanges have their own requirements for the groove flanks.
- The reference is the standard serrated gasket face (concentric or spiral, Ra 3.2 to 6.3 µm).
For EN pipe flanges there is no table of this kind – what applies there is explained on the page Tolerances.
Basis: ASME B16.5-2025 and EN 1092-1:2018 as test reference – statements about the standards, no standard text. Approval in an individual case is given by the manufacturer or by the purchaser with their specification.
Frequently asked questions
What is the difference between ASME B16.47 series A and series B?
Series A (formerly MSS SP-44) is heavier with fewer, larger bolts, series B (formerly API 605) lighter with more, smaller bolts - the two bolt patterns do not match. The dimension table on this page gives the dimensions per series, class and NPS in millimetres with inches in brackets.
Measuring the part yourself? Bolt circle W, outside diameter O, holes and tf without the raised face – and how to tell Class 150 from Class 300 on the part. How to measure correctly
About this dimension table
B16.5 ends at NPS 24 – large pipe flanges are covered by B16.47, in two series with different bolt patterns. Choose series, class and NPS and read the connection dimensions in millimetres with inches in brackets.
Types: weld neck, blind
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