Seawater Refredgerator scale problem

[SHARQ]

We use a refrigerator H/E to cool seawater before we return it back to the sea. We did not ?open this refrigerator for more than 6 years. We opened the refrigerator and found ?very hard scale in the tubes. The tubes are made of monel. I have a question with three ?parts


?1-? The scale is hard to remove when we used hydro jetting. We reached 14,000 ?Psi but still the scale is there. What will be the maximum allowable jetting ?pressure we can reach to clean??
?2-? We did chemical cleaning and it cleaned the tubes 70% only. We repeated the ?chemical cleaning again and there was no significant affect on removing the ?scale remained. the scale is consists of silica. My question is what is the best ?chemical solution we should use to do chemical cleaning??
?3-? We noticed there are some bulging at the end of the tubes (in the tube sheet ?area). I want to know what caused the bulging to be there? This bulging ?caused the refrigerator to fail in the pressure test. And we are not sure if we ?can only do expanding the tube or better to retube it again. What is the best ?way to return back the refrigerator to its normal condition? ?


Apppreciating your help on this regard

SHARQ

 

[Transient1]

I take it just replacing the tubes is not an option?

 

[EdStainless]

Are you sure that the bulging was not casue by the high pressure jetting? I have seen tubes torn out of tube sheets in hydroblasting.

Silica in Monel, I don't think that you can chemically disolve it without damaging the tubes.

= = = = = = = = = = = = = = = = = = = =
Rust never sleeps
Neither should your protection

http://www.trent-tube.com/contact/Tech_Assist.cfm

 

[SHARQ]

EdStainless:

We do chemical cleaning for the refrigerator every 4 years. Because we do eddy current test on it. The tubes can not be subjected to eddy current test unless it is cleaned well. The chemical cleaning is conducted by using some HCL 4% concentration. The result of the chemical cleaning is perfect.

On the other hand; the bulging concave inside the tube not outside. if it because of chemical cleaning we would see the bulging is causing the tube to deform towards the outer radius.

is there a way to upload some pictures to show you how is the bulging shape is?

SHARQ