Shell and tube exchanger with stationary tubesheets
Shell and tube exchanger with stationary tubesheets
(OP)
Hello everyone
I have a question referring design/construction of shell and tube heat exchanger.
Dose anybody meet in own design practice bellow described design case:
Shell and tube exchanger with stationary/fixed tubesheets with relief grooves at connection between tubesheets and shell./
Some amount of tubes go across part of relief groove, OTL has diameter covered part of it closer to the center of tubesheet.
Is such solution acceptable? My client said that yes but in my eyes it is wrong. At the point of contact between tubes with surface of groove additional stress concentration can occur and further we loose main task of groove.
Unfortunately, client till now dose not allow to increased I.D. of the shell and process engineer who design exchanger from the process point of view said that there is only small addition in exchange surface and reduction of tubes is really the last solution. Moreover, neither ASME in subsection UHX nor THEMA do not give any information/requirements for relief grooves.
Thank you in advance for any answer or opinion.
I have a question referring design/construction of shell and tube heat exchanger.
Dose anybody meet in own design practice bellow described design case:
Shell and tube exchanger with stationary/fixed tubesheets with relief grooves at connection between tubesheets and shell./
Some amount of tubes go across part of relief groove, OTL has diameter covered part of it closer to the center of tubesheet.
Is such solution acceptable? My client said that yes but in my eyes it is wrong. At the point of contact between tubes with surface of groove additional stress concentration can occur and further we loose main task of groove.
Unfortunately, client till now dose not allow to increased I.D. of the shell and process engineer who design exchanger from the process point of view said that there is only small addition in exchange surface and reduction of tubes is really the last solution. Moreover, neither ASME in subsection UHX nor THEMA do not give any information/requirements for relief grooves.
Thank you in advance for any answer or opinion.





RE: Shell and tube exchanger with stationary tubesheets
This new to me and we have numerous fixed tubesheet exchangers.
RE: Shell and tube exchanger with stationary tubesheets
1)You can ask client to show if they have done any similar design in past which is working properly.
2) UHX/TEMA does not address such configuration. Client has to prove that this design is safe. He might propose to do FEA. But in that case he should do detailed FEA & not any simplified FEA based on some assumptions. The operating conditions for FEA should be specified accurately. It is also necessary to carry out FEA for startup, shutdown, accidental, upset conditions etc.
In my opinion such configuration should be avoided. (especially if the exchanger is subjected to frequent cycles (fatigue).)
RE: Shell and tube exchanger with stationary tubesheets
I have done in same way as you proposed. I have askesd client to confirm such design and his good experiance in this, but i have only received answer: Yes, we have used such solution in the past and our experiance is good.
But such answer dose not convince me and thereofore my question.
RE: Shell and tube exchanger with stationary tubesheets
As unclesyd said, post the sketch of this configuration. This is to make sure that what we have imagined is correct. (since we have never seen something like this)
RE: Shell and tube exchanger with stationary tubesheets
Thanks for help.
RE: Shell and tube exchanger with stationary tubesheets
Can you comeback with the physical parameters and process fluids?
The only thing I've seen is we experimented with machining such a groove in SS tubesheets on vertical exchangers to mitigate Chloride SCC. We took our tubesheet vents from the groove area. The experiment failed in our case as the tubesheets would get a crown and the Chlorides would accumulate there.
RE: Shell and tube exchanger with stationary tubesheets
While I think the configuration is a little weird, assuming it meets the requirements of UW-13 etc. as to radius, TS thickness, etc. I would not be too concerned about stress concentration, this is Div. 1 design after all. The gain in surface above rated is surely negligible, lets don't assign a degree of accuracy to these calculations that does not exist.
Strictly speaking I doubt it is within the scope of UHX, but nothing unusual about that.
You for sure would not want to roll into the groove.
I'm glad it's not mine:)
Regards,
Mike
RE: Shell and tube exchanger with stationary tubesheets
I have looked into UHX and have not find requirements regarding such construction.
I thing that at the end we increase diameter of shell to reach more space to locate tubes, but is only one condition - the client agreement.
Regards
Arti
RE: Shell and tube exchanger with stationary tubesheets