Flanges by standard
ASME B16.47 large diameter flanges for data center mains
Hyperscale cooling plants run chilled water and condenser water headers well above 24 inches. ASME B16.47 picks up where B16.5 stops, covering weld neck and blind flanges from NPS 26 to NPS 60 in two series.
Use ASME B16.47 when a data center header above 24 inches is specified to ASME. Name the series on every line item: Series A and Series B flanges of the same size do not bolt together.
Series A and Series B
ASME B16.47, Large Diameter Steel Flanges, merged two older standards. Series A comes from MSS SP-44 and is the heavier design with fewer, larger bolts. Series B comes from API 605 and is lighter and more compact, with more, smaller bolts. Both series cover NPS 26 to 60, but only weld neck and blind flanges.
| Property | Series A | Series B |
|---|---|---|
| Origin | MSS SP-44 | API 605 |
| Classes | 150, 300, 400, 600, 900 | 75, 150, 300, 400, 600, 900 |
| Bolting | Fewer, larger bolts | More, smaller bolts |
| Weight | Heavier | Lighter |
| Interchangeable | With Series A only | With Series B only |
Where large flanges appear in a data center
A hyperscale campus can reject tens of megawatts of heat through a single central plant. The headers that link chillers, cooling towers and the facility water distribution are often 30 to 48 inches. Large flanges sit at:
- Chiller and heat exchanger nozzles on the condenser and evaporator sides
- Isolation valves that let one chiller or tower cell be taken out of service
- Header ends and future tie-ins, closed with blind flanges until the next phase is built
- Strainers and flow meters on the main supply and return lines
Large butterfly valves are supplied drilled to one standard. A Series A valve will not bolt to a Series B flange, and neither will match an AWWA C207 flange in every size. Confirm the valve schedule before ordering flanges.
Materials and testing
We supply B16.47 flanges in carbon steel A105 and A350 LF2, and in stainless 304L and 316L for stainless facility water and heat reuse systems. Large flanges carry the same marking and EN 10204 3.1 certification as our B16.5 range, and third-party inspection can be arranged at our works.
Alternatives above 24 inches
On water service, AWWA C207 steel flanges and AWWA C228 stainless flanges are lighter options rated for the pressures water systems need. Our guide to AWWA versus ASME flanges sets out when each makes sense.
Frequently asked questions
Are Series A and Series B flanges interchangeable?
No. For the same size and class, the two series have different outside diameters, bolt circles and bolt counts. Series B flanges are lighter, with more and smaller bolts. Check the series on the mating valve or equipment before ordering.
Does ASME B16.47 include slip-on flanges?
No. ASME B16.47 covers weld neck and blind flanges only. For large slip-on or ring flanges on water mains, specify AWWA C207 or a project drawing.
Should a 36 inch chilled water main use B16.47 or AWWA C207?
Both are used. B16.47 suits projects whose piping specification is ASME throughout. AWWA C207 is lighter and common on large condenser and chilled water mains in the United States. Mating valves decide it: match their flange standard.