ASME B16.47 Series B Flanges
Series B is the lighter, compact series, carried over from API 605. It uses a smaller outside diameter and a larger number of smaller-diameter bolts, which makes it thinner and cheaper but leaves less flange rigidity. It also carries a Class 75 rating that Series A does not. In Classes 400, 600 and 900 it has dimensions of its own through NPS 36 only; from NPS 38 up it uses the Series A dimensions.
- Standard
- ASME B16.47
- Series
- Series B
- Derived from
- API 605
- Sizes
- NPS 26 through NPS 60, Class 900 through NPS 48
- Classes
- 75, 150, 300, 400, 600 and 900
Not interchangeable with Series A. The two series differ in outside diameter, bolt circle and bolt count in Classes 75, 150 and 300, and in NPS 36 and smaller in the higher classes. At NPS 38 and larger in Classes 400, 600 and 900 the two series have the same dimensions. Never mix them in a joint without checking.
Common questions
What is ASME B16.47 Series B?
Series B is the lighter, compact series, carried over from API 605. It uses a smaller outside diameter and a larger number of smaller-diameter bolts, which makes it thinner and cheaper but leaves less flange rigidity. It also carries a Class 75 rating that Series A does not. In Classes 400, 600 and 900 it has dimensions of its own through NPS 36 only; from NPS 38 up it uses the Series A dimensions.
What classes does Series B come in?
Class 75, Class 150, Class 300, Class 400, Class 600 and Class 900, in sizes nps 26 through nps 60, class 900 through nps 48. Series A carries Class 150, Class 300, Class 400, Class 600 and Class 900 instead, which is one reason the two are easy to confuse on a requisition.