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ASME B16.47-2025

Large Diameter Steel Flanges: NPS 26 through NPS 60 Metric/Inch Standard
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ASME B16.47-2025

Large Diameter Steel Flanges: NPS 26 through NPS 60 Metric/Inch Standard

PUBLISH DATE 2025
PAGES 142
ASME B16.47-2025

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:

  • Rating Classes: 75, 150, 300, 400, 600, and 900.
  • Flange Types: Welding Neck and Blind Flanges.
  • Materials: Flanges made from forged, cast, or plate materials (for blind flanges) in various steel alloys (carbon steel, stainless steel, etc.).

A key aspect of ASME B16.47 is that it is divided into two distinct dimensional standards that are not interchangeable:

  • Series A (MSS SP-44 derived): Generally heavier, thicker flanges that use fewer, larger bolts. Often preferred for high-stress applications.
  • Series B (API 605 derived): Generally lighter, thinner flanges that use more, smaller bolts. Often preferred for pipeline applications where weight and cost are factors.

Application and Use

ASME B16.47 is used by technical professionals to define and procure the end connections for large pipes in heavy industry:

  • Design Engineers: They use the pressure-temperature rating tables to select the appropriate flange Series (A or B) and Class for the operating conditions of their system. They specify the dimensions, bolt requirements, and tolerances dictated by the standard.
  • Manufacturers: They use the precise dimensional data, including facing types (Raised Face, Ring Type Joint, etc.), bolt circle diameter, and bolt hole quantity, to ensure the flanges they produce meet the standard and will mate correctly in the field.
  • Pipe Fabricators and Installers: They rely on the standard to ensure that large-bore pipe sections, valves, and equipment (such as pressure vessels) can be reliably bolted together using the correct number and size of fasteners.

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
Publish Date Document Id Type View
May 30, 2025 ASME B16.47-2025 Revision