ASME B16.47 Flange Standard

The main difference between ASME B16.47 Series A and Series B flanges lies in their design dimensions, bolt patterns, and load capacity, even though both cover sizes from 26″ to 60″ and are used for similar applications.

Engineers often choose Series A for higher mechanical strength, while Series B is selected for cost-effectiveness and compatibility with older systems.

Selecting between ASME B16.47 Series A and Series B flanges depends on several technical and project-specific factors, such as space constraints, pressure requirements, system design, and legacy compatibility.

Key Factors to Consider:

• Pressure & Load Conditions:
  • Choose Series A when the system requires higher mechanical strength and operates under more critical pressure loads.
• Space & Weight Considerations:
  • Choose Series B when installation space is limited or weight reduction is a priority — ideal for compact piping layouts.
• Project Specification or Legacy Systems:
  • Use Series B if your system follows older API 605 standards or existing flanges are Series B.
  • Use Series A for newer specifications or EPC projects that call for stronger, thicker flange profiles.
• Cost & Material Optimization:
  • Series B flanges are more economical due to reduced material volume.

Always check the design pressure, gasket type, and companion flange compatibility before making a final selection. For custom projects, consulting the project piping class or a qualified engineer is essential.

ASME B16.47 flanges are available in a range of pressure classes that determine their maximum allowable pressure under different temperature conditions. These ratings are defined by ASME standards and are critical when selecting flanges for high-performance piping systems.

Pressure Class Breakdown:

1. Series A (MSS SP-44 based):
   • Available in Class 150, 300, 400, 600, and 900
2. Series B (API 605 based):
   • Available in Class 75, 150, 300, 400, 600, and 900

Key Points:

• The pressure class determines the wall thickness, number and size of bolts, and flange dimensions.
• These classes also relate to the flange’s temperature-pressure rating as per ASME B16.47 pressure-temperature charts.
• Higher class = greater strength and sealing capacity.

Always consult the ASME pressure-temperature rating tables to ensure the selected flange class meets the operational pressure at the specified service temperature.

No, ASME B16.47 flanges are not interchangeable with ASME B16.5 flanges, as they are designed for different size ranges and dimensional standards.

Key Differences:

• Size Range:
  • ASME B16.5: Covers flanges from ½″ to 24″ (DN15 to DN600)
  • ASME B16.47: Starts from 26″ to 60″ (DN650 to DN1500)
• Bolt Hole Patterns & Dimensions:
  • The bolt circle diameters, number of bolts, and flange thicknesses differ completely and cannot be matched or bolted together.
• Applicable Standards:
  • These two flange types are governed by distinct technical criteria, and their usage depends on system design specifications.

If a pipeline or equipment has a 24″ or smaller nozzle, B16.5 flanges must be used. For anything larger, B16.47 is required. Adapters or transition flanges may be needed if connecting across standards.

The gasket selection for ASME B16.47 Series A & B flanges depends on the flange facing type, operating pressure, temperature, and media compatibility. Both Series A and Series B flanges are commonly available in Raised Face (RF) or Ring Type Joint (RTJ) facings.

Compatible Gasket Types:

• For Raised Face (RF) Flanges:
  • Spiral Wound Gaskets (with or without inner/outer rings)
  • Soft Gaskets (Compressed Non-Asbestos, PTFE)
  • Metal Jacketed Gaskets
  • Corrugated Gaskets
• For Ring Type Joint (RTJ) Flanges:
  • RTJ Ring Gaskets — typically Oval or Octagonal, as per API 6A / ASME B16.20

Selection Notes:

• Ensure the gasket material is compatible with the temperature and pressure class of the flange.
• Gasket dimensions must match the Series A or Series B bolt circle and groove specs exactly.
• Always refer to ASME B16.20 for metallic gasket construction guidelines.

Proper gasket selection ensures leak-free sealing and long-term performance in critical service applications like oil & gas, offshore, and chemical processing.

Nutech Overseas is a trusted global exporter of ASME B16.47 Series A and Series B flanges, supplying premium-quality Weld Neck and Blind flanges to customers across oil & gas, petrochemical, marine, and power sectors in more than 40 countries.

Key Export Destinations Include:

• Middle East: United Arab Emirates (UAE), Saudi Arabia, Oman, Qatar, Kuwait, Bahrain
• Asia: Singapore, Malaysia, Indonesia, Vietnam, Philippines
• Europe: Germany, Italy, Spain, Netherlands, Poland, France
• North America: United States, Canada, Mexico
• Africa: Egypt, Nigeria, South Africa, Algeria
• South America: Brazil, Chile
• CIS & Russia: Kazakhstan, Uzbekistan, Russia

We provides custom packaging, documentation (EN 10204 3.1/3.2, PED, NACE), and logistics support to ensure seamless and timely delivery of flanges globally.