The Difference Between ASME B16.47 Series A and Series B Flanges?

ASME B16.47 is a standard published by the American Society of Mechanical Engineers (ASME) that covers large diameter steel flanges. The standard is divided into two series: Series A and Series B. Here are the main differences between ASME B16.47 Series A and Series B flanges:

1. Flange Dimensions: The dimensions of Series A and Series B flanges differ. Series A flanges have larger dimensions compared to Series B flanges. This means that Series A flanges have larger outside diameters, bolt circle diameters, and overall thicknesses compared to Series B flanges.

2. Pressure Ratings: Series A flanges have higher pressure ratings compared to Series B flanges. The pressure ratings for Series A flanges are typically in line with ASME B16.5 standard pressure classes, while Series B flanges have lower pressure ratings.

3. Face-to-Face Dimensions: The face-to-face dimensions of Series A and Series B flanges also differ. Series A flanges have larger face-to-face dimensions compared to Series B flanges. This affects the overall length of the flange and can impact the layout and design of piping systems.


4. Applicability: ASME B16.47 Series A flanges are generally used for large diameter, high-pressure applications. They are commonly found in industries such as oil and gas, petrochemicals, and power generation. ASME B16.47 Series B flanges are typically used for lower-pressure applications and are less common in industrial settings.

It’s important to note that the selection of the appropriate flange series depends on the specific application requirements, including pressure, temperature, and design considerations. Consulting with engineering professionals and following industry standards and guidelines is recommended to ensure the correct flange series is chosen for a particular application.

Flange B16.5, which refers to the ANSI standard for pipe flanges and flanged fittings, can be manufactured using a variety of materials depending on the specific application requirements. Here are some commonly used materials for B16.5 big OD flanges:

1. Carbon Steel: Carbon steel flanges are widely used due to their strength and affordability. Common grades of carbon steel used for flanges include ASTM A105/A105N and ASTM A350 LF2.

2. Stainless Steel: Stainless steel flanges are preferred when corrosion resistance is required. Common grades used include ASTM A182 F304/F304L, F316/F316L, F321, and F347.

3. Alloy Steel: Alloy steel flanges are used for applications that require higher strength and better performance at elevated temperatures. Common grades used include ASTM A182 F5, F9, F11, F22, and F91.

4. Duplex and Super Duplex Stainless Steel: These materials offer enhanced corrosion resistance and are suitable for demanding environments. Common grades used include ASTM A182 F51 (Duplex) and ASTM A182 F53/F55 (Super Duplex).

5. Nickel Alloys: Nickel alloy flanges are used in applications requiring exceptional corrosion resistance and high-temperature strength. Common materials used include Inconel, Hastelloy, Monel, and Alloy 20.

6. Titanium: Titanium flanges are used in industries where lightweight, high strength, and excellent corrosion resistance are required. Common grade used is ASTM B381 Grade 2.

7. Copper Nickel: Copper nickel flanges are used in marine and offshore applications due to their excellent resistance to seawater corrosion. Common grade used is ASTM B151 C70600 (90/10 Copper Nickel).

It’s important to select the appropriate material based on factors such as the type of fluid or gas being conveyed, temperature, pressure, and corrosion resistance requirements. It is recommended to consult with industry standards, guidelines, and engineering professionals to determine the most suitable material for your specific application.