Flange Serie A and Serie B 1

[HOUARI YAHIAOUI]

Hello everybody;
plz what is the difference between the two series A and B of flange for large diameter? and how to choose between the two?

 

[SnTMan]

IF you are referring to ASME B16.47 flanges, Series A flanges are physically larger than Series B. See 1.2

This make Series B generally preferred but you have to furnish whichever series is to be mated.

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[MGZmechanical]

If I'm not wrong A series come from water / liquid applications and series B comes from gas applications.

 

[KevinNZ]

Series A are larger with less, but larger studs, Series B is smaller with more studs.

From B16.47

Flange dimensions were based on the Manufacturers Standardization Society, Standard Practice (MSS SP) 44
flanges, except for Class 75 flanges that are ANSI/API 605 flanges.
At the request of the American Petroleum Institute (API), flange dimensions, in accordance with the API Standard 605,
were included in the subsequent drafts.
The API 605 flanges for Classes 150 and 300 and for sizes NPS 36 and smaller for classes higher than Class 300 are not
compatible with the MSS SP-44 flanges. [highlight #FCE94F]Thus, the MSS SP-44 flanges are designated as Series A flanges, and the API 605
flanges are designated as Series B flanges[/highlight] in this Standard. Materials covered in this Standard are as in ANSI B16.5, except
nickel base alloys are excluded. Pressure–temperature ratings are in accordance with ANSI B16.5.

 

[mk3223]

The B16.47 Series B flange is more compact dimensions than Series A. The usage of either Series of flanges could be case by case. Having a refining client who specifies the Series A flange to be used under normal condition, and the Series B flange may be used in low pressure system such as flare headers if necessary and suitable.

 

[marty007]

Many customers that I've worked with over the years will try to standardize their B16.47 flange series across their plant. They will often put in their standards that all B16.47 flanges must be series A or B.

The two series have different gasket dimensions. Standardizing helps in at least two ways:
[ol 1]
[li]It reduces the likelihood of an installer accidentally using the wrong gasket. Series B gaskets would typically fit in a series A flange, but wouldn't be the correct gasket. All the installer may consider is that it's a 36" flange, not thinking that different gaskets would be required.[/li]
[li]It reduces the number of spare gaskets that must be stored in the warehouse.[/li]
[/ol]

 

[bcd]

The background behind each is covered by KevinNZ reply. The API flange (series B) is more compact and is ideal for pipe-to-pipe connections. However, fitting this compact bolt pattern onto equipment that is installed into pipelines, such as valves, can be difficult to impossible. It is sometimes possible to get equipment like [pumps and valves with Series B flanges, but in general, equipment mostly uses Series A