Design of Tube Sheets of Single Tube Pass Floating Head HEX with Bellows in Floating Head Tail pipe.

[DK44]

Request following clarifications for Design of Tube sheets for a single Tube pass Floating Head Heat Exchanger (Ex: TEMA AES Type) having an Expansion bellow in the Tail Pipe at Floating Head.
1. What is the affect of Bellows (in respect of spring rate / Axial load etc) on the Tube sheet design.
2. Does ASME Sec VIII Div 1 cover the procedure for the design of Tube sheets for such condition.
3. Any worked out example available for such case?

 

[SnTMan]

DK44, in my experience, the presence of a bellows is not accounted for, neither under the old TEMA rules, nor under Part UHX rules. I suspect the reason is that the effect would be negligible. I suspect that the spring rate of a pipe-sized bellows joint is so low that this is so.

There is no explicit means under Part UHX to account for the bellows, however I imagine that if one wished to do so it could be done as follows:

1) The product of the spring rate and (worst case) displacement of the bellows, a force, could then rendered to an equivalent pressure acting on the floating tubesheet. This equivalent pressure would then be used to adjust either the shell or tubeside design pressure, depending whether the bellows is extended or compressed. (See the below discussion)

2) This adjusted pressure then is used to calculate the Part UXH quantity Pe, UHX-14.5.6.

3) The rest of the Part UHX calculations are completed as written.

I imagine it would be necessity to distinguish the bellows movement among the load cases per Part UHX 14.4(b)(1).

This is, in my opinion, the other reason the effect of the bellows is neglected. It complicates the calculations without necessarily improving their accuracy.

Regards,

Mike



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