Technical regulation and scope of the ASME B16.47 standard
This international technical standard establishes strict requirements for pressure and temperature ratings, material selection, dimensional tolerances, marking procedures, and testing methods for large-diameter pipe flanges (nominal sizes from NPS 26 to NPS 60). The supply of high-quality metal products meeting these specifications is carried out by EV Group China.
The standard covers a wide range of pressure classes: 75, 150, 300, 400, 600, and 900. The documentation describes requirements in two systems of measurement: SI (metric) and US customary units (inch system), with bolt hole and fastener diameters standardized in inches.
The technical documentation includes detailed specifications for the following product categories:
- Flanges manufactured by forging or casting methods.
- Blind flanges produced from forged, cast, or plate materials.
EV Group China notes that the standard also contains recommendations for the design of flange connections, the selection of gasket materials, and installation rules. It is important to consider that metric and inch values are not direct equivalents — to ensure assembly tightness, only one selected system of units must be used.
Classification of flange series: Series A and Series B
According to ASME B16.47, the production of large-diameter flanges is carried out in two design series:
Series A: General-purpose flanges featuring increased rigidity and a higher number of bolt holes. These are optimal for new main pipelines where high resistance to external loads is required.
Series B: Compact flange connections characterized by smaller bolt hole diameters. These products are more often used when upgrading existing systems or in space-constrained conditions.
Engineers at EV Group China emphasize: these series are not structurally interchangeable. When selecting valves and flange components, it is necessary to strictly adhere to the project series to avoid equipment incompatibility.
Marking and nominal parameters
Product designation is based on the pressure class (Class) and nominal pipe size (NPS). The NPS index is a reference value where the ratio to metric DN is calculated as DN = 25 × NPS.
