What Is ASME B16.47?
ASME B16.47 is the American National Standard for large-diameter steel flanges from NPS 26 through NPS 60, in pressure classes 150, 300, 400, 600, and 900. It provides two series: Series A (based on MSS SP-44, larger bolt circle) and Series B (based on API 605, smaller bolt circle).
Flange Types Covered
- Weld Neck — full-penetration butt weld, highest integrity
- Blind — for closing large-diameter lines
- Hub Flanges — slip-on / threaded hub configurations
Size & Class Range
| Parameter | Range |
|---|---|
| Size | NPS 26 – NPS 60 |
| Pressure class | Class 150 / 300 / 400 / 600 / 900 |
| Series | Series A (MSS SP-44) / Series B (API 605) |
| Materials | A105, A182 F304 / F316 / F321, A350 LF2 |
Relationship to ASME B16.5
ASME B16.5 covers flanges up to NPS 24; ASME B16.47 extends coverage to NPS 26–60. Choose the flange standard by your pipe size — not by pressure alone.
Related Standards
FAQ
What is the difference between Series A and Series B in B16.47?
Series A (MSS SP-44 heritage) has a larger outside diameter and bolt circle; Series B (API 605 heritage) is more compact. They are not interchangeable — always match the flange standard of your existing piping.
Does B16.47 cover flanges smaller than NPS 26?
No — sizes NPS 1/2 through NPS 24 are covered by ASME B16.5.
Which classes are available?
Class 150, 300, 400, 600, and 900, in both Series A and B.
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