Girth Flanges Design for Shell and Tube HE

[Simdro]

Hi Guys,

I'm checking for the design calculation of Fixed Tube Sheets HE (Tubesheets integral with Shell and Gasketed with Channel).
The channels are coupled to the Tube Sheets with girth channel flanges designed in accordance with ASME VIII Div.1 "Appendix 2".
Does anyone know if the channel flanges design shall consider, as equivalent design pressure, the exteernal loads due to the piping connection, considering that the examined channel is equipped with two 32" nozzles?

Thank you in advance for your co-operation.

 

[DonKurle]

Simdro,

If the external loads are resisted by the body flanges, usually they are, then they must be considered as they are UG-22 loadings. Currently, Section VIII-1 does not provide a method to consider the loads, an equivalent pressure method or some other method is acceptable (see U-2(g)) as long as your AI is in agreement.

DonKurle

 

[gr2vessels]

Simdro,
The PV Elite does consider the effect of those nozzle loads and I, for one, would always include the Channel nozzle loads in the Channel flange calculations. Even if the Client specification does not make specific request for inclusion of these loads, they van be significant and ending in leaking joint if not taken in consideration. I have seen completed exchanger on site which would never seal, despite of perfect hydrotest. A quick review of the input data revealed the missing loads. Depending what software you are using, you could include the known loads or include some 40 x DN forces(N) + 60 x DN moments (Nm) or calculate and include the equivalent pressure per Dennis Moss calculation. Never trust the minimum thickness as calculated by the software, unless included all the loads affecting the girth flange.
Cheers,
gr2vessels

 

[Simdro]

Thank you very much DonKurle and Gr2Vessles.

The calculation was made by Microprotol and it did not take into account the external loads acting on channel.
Therefore I'll take the real external loads acting on channel evaluated by stress analasys guys and will calculate the equivalent design pressure as per Dennis Moss Calcualtion.

Moreover the rigifity factor "J", as per ASME VIII Div.1 Appendix 2 (point 2-14), in operating conditions without external oveloads is already exceeding the unit.

I think that the application of external loads could surely make worse the actual situation.

Thanks again bye bye