Shell & Tube HE - Tubes under External Pressure
Shell & Tube HE - Tubes under External Pressure
(OP)
Hi,
I'm working on a project where the shell side is rated 350/-15 psig while the tube side is rated 200/-15 psig. In my mind, the tubes could theoretically experience 350 psig external pressure, which is not what it's rated for. I can't seem to find very much literature on a HE where the shell side is at a higher pressure than the tubes. I'm specifically analyzing a tube rupture case where the shell ruptures the tubes, pressurizing them beyond it's MAWP. Can anyone provide some guidance on how to approach this?
Thanks!
I'm working on a project where the shell side is rated 350/-15 psig while the tube side is rated 200/-15 psig. In my mind, the tubes could theoretically experience 350 psig external pressure, which is not what it's rated for. I can't seem to find very much literature on a HE where the shell side is at a higher pressure than the tubes. I'm specifically analyzing a tube rupture case where the shell ruptures the tubes, pressurizing them beyond it's MAWP. Can anyone provide some guidance on how to approach this?
Thanks!





RE: Shell & Tube HE - Tubes under External Pressure
This is also a matter of economics.
Significant savings can be gained if the cost of the HX can be decreased by decreasing the system design pressure through use of a relief device.
MJCronin
Sr. Process Engineer
RE: Shell & Tube HE - Tubes under External Pressure
Now as to overpressure protection in the event of tube rupture, one approach is to a install a relief device as per MJCronin. Another commonly used is to set the low side design pressure such that in the event of a tube rupture, the low side is exposed to maximum stresses corresponding to its stresses at hydrotest.
So, for your example the tubeside pressure would be set at 1/1.3 * (350+15), or 281 psig.
In the old days this was known as the "two-thirds" rule (1/1.5), now I guess its the "ten-thirteenths" rule :)
Regards,
Mike
RE: Shell & Tube HE - Tubes under External Pressure
Regards,
Luis C.