Bore diameter "B" Flange ASME B 16.5

[aaloui]

Hi,

for high rating and/or large size flanges in ASME B 16.5 the bore diameter (Dimension B) is not specified in the dimensions tables.
It's stated there that this is to be specified by the purchaser.
My question is, how to specify this dimension such that the flange will "still" conform to the standard B 16.5 and in particular to the rating tables there?
The paragraph 2.7 of the standard provides a formula for determining the maximum B, but I am not sure if this is what I have to do?
The text in this paragraph is not clear for me.

Thank you

 

[saplanti]

You need to look at the connected pipe wall thickness and specify the same for the flange.

If you use Sch STD for the pipe use Sch STD for the flange.

 

[aaloui]

Thank you saplanti.
Regards
aaloui

 

[LittleInch]

Just be careful about mixing flanges and pipe of different strength materials though. That's a whole different thing...

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[aaloui]

As I understood, the hub thickness shall be determined as a pipe under internal pressure (for example using the formula of ASME B31 oder ASME Section VIII).
The material will be the flange material.

I'am thankful if someone can tell me the meaning or the background of the equation Bmax=Ah(1-CoPc/50,000) stated in paragraph 2.7 of ASME B 16.5.
I could not understand it, nor I could reproduce the bore diameter in the dimensional tables using this equation.

Thank you

 

[jt1234]

Don't mix up piping code to vessel code. They have their own criteria to calculate bore thickness. It is very common that nozzle can be XS while piping is STD bore. Don't be surprised more than 50% are in this case for a typical petrochemical plant, and most of the time it won't create any process issue. So I disagree with saplanti.

 

[saplanti]

aaloui,

I guess you are a flange forging manufacturer, and you were given very little information that you are not familiar.

Full bore and reduced bore is a terminology that used mostly in valves. Normally the internal diameter of the piping for a dedicated line is called full bore. It may change with the line required thickness. The full bore flange means that the internal diameter of the flange has to match the internal diameter of the piping.

ASME B16.5 therefore does not give the internal diameter, it leaves it to the purchaser to comply with the pipe specification.

In case you have not given any of these you ask the client of yours to give it to you, either the pipe wall thickness or the flange specification.

I hope this clarifies everything for you.