API 660 loads on BEM Heat Exchanger Channel with Concentric Cone

[FPPE]

Hi,

I'm designing a BEM heat exchanger with concentric cone and I have a doubt on evaluation of API 660 loads.
Design code is ASME VIII-1 2023 and equipment shall be marked with U designator.
Design conditions tube side: 1.77 MPa + FV @ 100 °C
Tube side MOC: SS316
Please consider the following sketch:



As you can see, I have to consider API 660 values for external loads on nozzles.
I need the following clarification:

1) API loads are applied at the intersection of shell to nozzle junction. In this case we do not have a shell, but a girth flange connected to the extended portion of tubesheet.
This seems to be a case which should be evaluated only by FEA, but API loads should be applied on flange resulting critical than the ones applied at the junction as required by standard itself.
2) Gasket of flange-tubesheet joint is a GMGC kammprofile type and there are No. 36 (0.875"). Radial load on nozzle could be a problem for flange leakege?

Is there a way to consider those loads applied on flange by formulas for which we can avoid the FEA? Is it possible in software such us PV Elite?
Do you have any other advice for these design?

Thanks in advance

 

[Trestala]

The API 660 nozzle load values are just a standard table used as reference in the design. When used, it acts as a starting point where you can design your nozzle connections (e.g. local stress at the nozzle-shell junction) and also acts as a limit for the Piping team for the loading that their piping will impose to equipment's nozzle.

Even those API 660 values are specified as acting on the nozzle-to-shell junction, those values have to be aligned with your Piping team on what is the actual loading being applied to your flange connection. You can align with your piping team that the API 660 standard load values will be considered to act on the 20" flange connection since you don't have a shell. Or have a different set of design load values acting on the 20" flange.

You don't necessarily need to use FEA to evaluate the girth flange-to-tubesheet connection. You can just account for the super-imposed axial load and moment coming from the 20" flange to the girth flange-to-tubesheet. There are different approaches, and you could probably convert those nozzle load values into an equivalent pressure that can be included in the flange and tubesheet calculations.

 

[FPPE]

Hi Trestala,

Thank you very much for your answer.
Could you kindly provide a reference for the equivalent pressure calculation?

Thank you