As per ASME procedure, the stresses in the tubesheet should be checked for different load cases ( 3 load cases for U tube tubesheet & 7 load cases for fixed tubesheet). However in general which load case can be dominating the tubesheet stresses ?

I think there is no general case that always contribute to maximum stresses in the tubesheet. Check all cases and find out which is more conservative for your application.

Thanks.

Mukesh

Thanks Mukesh,

For your kind reply

Dear all

while designing the tubesheet in the fixed tube heat exchanager?

Generated stress are very higher.

Which type of stress are critical in the fixed tubesheet or when we designed the fixed tubesheet is there any relevance with the expansion bellow?

Which type of expansion bellow is more used to reduces the actual stress?

As to the original question posed, the greatest stress can be in any component. Therefor all 7 (or 3) load cases have to be considered to determine the governing case.

You have a lot of questions,

In a fixed tubesheet exchanger, there is a problem of differential thermal expansion between shells and tubes. Tubes may expand at different rate than the shell, creating pushing/pulling at the tubesheet.

Hence, the metal temperatures of tube and shell are very important. They should be as accurate as possible.

An expansion joint will reduce this thermal expansion problem.

A bellows exp. jt. is lot more flexible than the thick (flanged and flued) expansion jt.

While going through the literature about knuckle tubesheets, I came across the term Stayed tubes. What does this mean?