MJC,
Thanks for your reply...
The fluids we´re talking about are Natrium (Sodium) / Isoprene on one side, cooling water on the other.
So we don´t want any cooling water near Sodium...! (the tubes ar also Bi-metallic).
What i need to know is: When they use a double tube sheet , are there around the tubes secondary tubes.
If Yes: * Only between the "double" tube sheets.
* Or, over the full length of the Heat Exchanger.
Mvg.
Jeroen