To keep them from leaking?

Your question may be worded a bit ambiguously. The seal I believe that you are referring to is the level in the subcooling zone of the heater. You need to keep this level above a certain point to avoid steam from flashing between a vapor and a liquid in the subcooler area. If this occurs, you can have damaging water hammer.

That depends on if he means sealing between the tubes and the steam section or as you state the sub cooling area.

If he intends the tube seals it is to prevent loss of feedwater into the steam chamber. We just changed out the tubes for a feedwater heater and had difficulty when rolling the tubes to seal them in the plate separating the steam from the feedwater header.

There isn't any physical seal separating the subcooling section from the condensing section. Separation is achieved by maintaining sufficient water level in the bottom of the feedwater heater to completely cover the entrance to the sub cooling section.

Drew K

Banu,

Try to learn the normal and cutomary parts of a feedwater heater and then identify exactly WHERE this water seal is located.

Are you refering to the subcooling zone..... or what ?

C'mon....we all know you can do it !!!

Try to use just a few more English words in your questions and we will all be happy !!!