Large Diameter Steel Flanges: NPS 26 through NPS 60 Metric/Inch Standard
Purpose and Scope of ASME B16.47-2025
ASME B16.47, Large Diameter Steel Flanges: NPS 26 through NPS 60, standardizes the mechanical and dimensional characteristics of welding neck and blind pipe flanges that are too large to be covered by the more common ASME B16.5 standard (which covers up to NPS 24).
Its primary goal is to ensure that large-scale piping systems—common in petrochemical, power generation, and waterworks facilities—can be built safely and consistently by providing fixed specifications for these critical, pressure-retaining components. This standardization greatly simplifies design, procurement, and field assembly.
The scope of the standard covers flanges with a Nominal Pipe Size (NPS) from 26 through 60, across several pressure-temperature rating classes:
A key aspect of ASME B16.47 is that it is divided into two distinct dimensional standards that are not interchangeable:
Application and Use
ASME B16.47 is used by technical professionals to define and procure the end connections for large pipes in heavy industry:
In essence, the standard ensures that a flange specified as an NPS 30, Class 600, Series A welding neck flange from any compliant manufacturer will physically and safely connect to any other matching component, regardless of origin, maintaining the mechanical integrity of the entire piping system.
| SDO | ASME: American Society of Mechanical Engineers |
| Document Number | B16.47 |
| Publication Date | May 30, 2025 |
| Language | en - English |
| Page Count | 142 |
| Revision Level | |
| Supercedes | |
| Committee |