Condenser tube thickness problem and corroded

[pamungkas]

hi all,
The condensers of our 5 MW steam turbine has problem decreasing in thickness/leakage. We use sea water as cooling water. The condenser have 2 inlet of cooling water, NORTH and SOUTH. The NORTH side is higher in pressure rahter than the SOUTH. Eddy Current Test showed that the SOUTH side have more tubes (significant) defect rather than the NORTH. Can any one tell me:
1. Does different pressure NORTH and SOUTH (about 5KPa) in cooling water inlet create the defect in the SOUTH side (decreasing in thickness/leakage).
2. Is it any possibility that inside tube (condesate side) suffering corrosion?
3. We install Zn sacrificial anode for the tubes (Al brass) but the tubes still corroded. Why?

Thank you so much

regards.
pamungkas

 

[MJCronin]

pam,

I suggest that you repost under "Heat Transfer & Thermodynamics Engineering".

Sea water is pretty nasty stuff....It can corrode at various temperature ranges and can vary properties and salt concentrations throughout the year.

What is your tube material and who made your condenser ?

Is the sea water inside or outside of your tubes ?( I do not understand your item #2 above)

MJC

"There comes a time in the affairs of man when he must take the bull by the tail and face the situation." W.C. Fields

 

[pamungkas]

Thank you for your sugestion. I will get to try it.
For the item no 2. The sea water is in outside tubes. It was Pieter Brotherhood manufactured. 14 years old.

Thanks again.

Pamungkas

 

[abeltio]

Careful with Zn in applications with temperatures higher than ambient... it reverses polarity above 65degC so it protects itself using the tubes as sacrificial anodes...
Check the NACE standards.


saludos.
a.