Painting inside chiller condenser vessel

[syk35]

Hi guys

I have a problem with corrosion in a water cooled chiller vessel. Anyone have experience with painting water cooled chiller condenser vessels inside the ends to reduce corrosion? Epoxy paint seems to be used. If water treatment is correct will the steel surfaces corrode? The system that I have open at the moment has a mix of copper and steel tubing for the condenser water pipework, the steel pipework is very rusted inside and looks to be adding to my problem. What are your thoughts on painting these steel surfaces? Would having only copper pipework reduce corrosion issues?

Thanks

[chillerman2006]

Hi Syk

it sounds like masking a problem to me and if painted over and this lifts off, it will block the filters quicker than disolved rust, personally I would want a new vessel fitted & then make sure the water treatment is carried out properly to ensure maximum life, I normally find problems with scaling due to poor water treatment, causing heat transfer issues, when removed this is when the damage is exposed....depending on how bad your problem is you could be looking at another issue soon...water in the fridge system....massive clean up problem, can take compressors out too

R's chillerman

[Grizzly]

Get a water treatment company involved with the correct additives rust can be removed. Scale can be broken down and filtered out.
You can even get little microbes that eat steel.
Skimp on the correct water treatment and all sorts of Cr*p can develop.
Chilled water seems to be the worst, if you run with glycol added you don't seem to get the same problems.
I believe it is due to the oxygen levels in the water.
Treatment would be your long term solution.
So your question is correct and copper has antiseptic values so you don't get the same issues.

Chillerman has some good points to, it does seem to depend upon the extent of the damage you are having to deal with?
Good Luck Grizzly.
Ps. The longer you leave the problem the worse it will get.

[syk35]

The corrosion is just starting on the end plates, small pitting. Water treatment is being maintained, i have only recently found a design problem where in certain conditions (2 chillers running off a 1 of 2 cooling towers) that one tower overfills causing treated water to go straight down the drain. i have fixed this problem and now want to change all steel piping over to copper. What are peoples opinions on painted end plates? are most condensers left bare steel?

[Brian_UK]

If water treatment is correctly maintained then corrosion caused by excessive oxygen in the water shouldn't be a problem.

If you are proposing to change steel to copper piping then ensure that you don't generate galvanic erosion problems by having a plastic coupling between the two metals. Also get for stray earth currents going via the piped services.

[syk35]

If you are proposing to change steel to copper piping then ensure that you don't generate galvanic erosion problems by having a plastic coupling between the two metals. Also get for stray earth currents going via the piped services.

The connection onto the chiller is a victaulic connection, this is where steel piping is. Steel piping is from a flanged butterfly valve 2m away from entering and leaving connections to the condenser connections (about 4m of steel piping in total). The rest of the piping is in copper. How would i have a plastic coupling where the victaulic connection attaches to the condenser vessel?

[Magoo]

Pitting would indicate cathodic corrossion, the PH control of water is the problem, the water has gone acidic. There are additives available for closed loop chilled water systems.
By painting water boxes, you will shift the problem to somewhere else, don't paint.

[syk35]

thanks for the replies

[Emmett]

Magoo,
I think the problem he is reffering to is on the condenser side of the system which is open loop, however as you point out the pitting is a result of poor chemistry and must be adressed. Syk35, if you maintain proper water chemistry the steel piping will not be an issue.

Pitting would indicate cathodic corrossion, the PH control of water is the problem, the water has gone acidic. There are additives available for closed loop chilled water systems.
By painting water boxes, you will shift the problem to somewhere else, don't paint.

[Magoo]

Hi Emmett.
thanks for correction, as you say the problem is chemical. But I have had same situation on chilled water side of systems, where the steel pipework in a building sprung leaks everywhere.