Asme B16 47 Flange Series A Vs Series B

When selecting large diameter pipe flanges, choosing between Series A and Series B under the ASME B16.47 standard is a critical decision that affects safety, cost, and performance. In this blog, we will explore what ASME B16.47 is, define the two flange series, and break down 12 essential differences to help you determine the best fit for your project.

What is ASME B16.47?

ASME B16.47 is a standard developed by the American Society of Mechanical Engineers (ASME) that covers large diameter steel flanges ranging from NPS 26 to NPS 60. This standard specifies pressure-temperature ratings, materials, dimensions, tolerances, marking, and testing requirements for flanges commonly used in oil & gas, petrochemical, and water treatment industries.

The standard includes two flange types: Series A (formerly MSS SP-44) and Series B (formerly API 605). Each has unique characteristics tailored to different application needs.

What are Series A and Series B?

Series A Flanges: Designed for high-pressure applications. They offer greater strength due to thicker walls and require more bolts, making them ideal for demanding industrial systems.

Series B Flanges: More compact and lightweight. They use fewer bolts and are better suited for lower pressure systems where space and weight are considerations.

Both series are dimensionally distinct but conform to the overall requirements of ASME B16.47.

ASME B16.47 Flange Series A vs Series B: 12 Key Differences

Standard Origin

• Series A: Derived from MSS SP-44.
• Series B: Based on API 605.

Wall Thickness

• Series A: Thicker flange body offers higher mechanical strength.
• Series B: Thinner construction, suitable for moderate loads.

Weight

• Series A: Heavier due to increased thickness and bolt count.
• Series B: Lighter, easier to handle during installation.

Bolt Hole Diameter

• Series A: Typically smaller bolt holes.
• Series B: Larger bolt holes, often requiring wider gaskets.

Bolt Quantity and Configuration

• Series A: More bolt holes for improved sealing and strength.
• Series B: Fewer bolts to minimize cost and weight.

Available Flange Types

• Series A: Primarily available in weld neck and blind types.
• Series B: May offer broader availability including slip-on types in some custom applications.

Pressure Rating

• Series A: Higher pressure ratings make it ideal for critical systems.
• Series B: Suitable for lower-pressure applications.

Size Range

• Both: NPS 26 to NPS 60, but Series B may be preferred for retrofitting older pipelines.

Common Applications

• Series A: Power plants, refineries, high-pressure gas lines.
• Series B: Water lines, fire protection systems, and low-pressure pipelines.

Cost

• Series A: More material and labor-intensive = higher cost.
• Series B: Cost-effective for non-critical applications.

Flange Facing Diameter

• Series A: Larger facing diameter improves sealing area.
• Series B: Smaller facing diameter conserves space.

Compatibility and Standard Consistency

• Series A: More aligned with current ASME B16.5 design philosophy.
• Series B: Better suited when matching older flange systems.

Conclusion: How to Choose the Right Flange for Your Project

When deciding between Series A vs Series B flanges, consider your project’s pressure requirements, space constraints, budget, and compatibility with existing equipment.

• Choose Series A for higher strength, safety, and compliance in critical systems.
• Choose Series B when cost, weight, and installation speed are priorities in less demanding environments.

By understanding the differences outlined above, you can confidently select the flange type that delivers optimal performance and long-term value.

For more information on ASME B16.47, flange sizing, and industrial piping components, feel free to contact our technical team or explore our catalog.