Dear experts,
In Flange leakage calcualtion, surface finish has direct impact in calculation of effective gasket width(Facing sketch and column selection).Having a scenario where the two flanges (raised face serrated finish) having different surface finish. (One is other than 125-250 AARH)
How to carry out flange leakage check in this situation.
Does the type of serration has any impact too...??

Hi,
Flange surface finish is a critical aspect of gasket performance. Metallic, semi-metallic and non-metallic gasket materials interrelate with flange surfaces in a different way. Each of these gasket types require specific ranges of surface finish for most favourable gasket performance with respect to lowest leakage and operational safety. Metallic gaskets require a smoother flange finish than either semi-metallic or non-metallic types.

So as far as your surface finish point is concern you have to consult the manufacturer for the best combination of flange surface finish & gasket design along with the material of the gasket. So suggestion will be to carry out the flange leakage check once you finalized all the aspect of this assembly.

Comments are welcome.

Regadrs,
R.K.

Thank you for your information.
In my perticular case one flange is of the equipment nozzle already supplied. Now my querry is how to take care the situation while performing the check on CAESAR II detail flange leak check module.

To be specific there is a note in ASME-SEC8 Div 1 table 2-5.2: "where serration do not exceed 0.4 mm depth and 0.8 mm width spacing, skatches 1b and 1d shall be used."
which sketch to select if we exceed the above mentioned limits.


Regards,

Hi again,

Yes you are correct, but the main difference between 1b & 1d will be the factor "w" & "N". where "w" stands for the width based on the contact width between flange facing and gasket, while "N" stands for the possible contact width of the gasket.

1d can be used when you have w<=N, else go for 1b.

I hope this is clear. Let me know if something still unclear.

Regards,
R.K.