Coating a soft water tank

[pumphead]

1) Coating suggestions for a soft water tank?

We are planning to install a soft water tank in between our water softener and dearator on our boiler feedwater. It will also have a recovered condensate stream coming to it.
I was suggested to go with a carbon steel tank with an interior coating. Tank would be atmospheric, 160F max. Coating would protect from pitting caused by dissolved oxygen in the water.

 

[Goahead]

Hypalon® chlorosulfonated polyethylene sheets can be field seamed using either heat welding or solvent adhesives.
This material is highly resistant to a range of harsh conditions.

http://www.welding-advisers.com/

 

[mshimko]

Regardless of the coating type or brand; take multiple steps to ensure the tank surfaces are TOTALLY FREE of any chlorides or other contaminants.

I hope the tank is large enough to allow access for good surface preparation and QA.

 

[Ashereng]

We've used IMPREGLON 410M.

Would teflon also work? The temp is onl 160°F.

 

[TBP]

Why not just send the condensate directly to the DA? It normally just dumps in - no level control valve. The make-up water moves through the softeners and to the DA (through a LCV) with the municipal or plant water system pressure. No pumps, no tanks, no liners, no corrosion ... no foolin'.

 

[rustbuster]

We have had success with Devoe thin film epoxies. There are other good options as well.

 

[ssreese1500]

International Paint makes a product called Interline 925 that is an excellent high solids Epoxy Coating. I cant seem to find any data on it as to service temperature. The only problem with it is that the steel must be grit blasted to near white condition before application, and and surface rust that flashes must be removed before application. Interline 850 is also a good product and is a lot easier to use than 925, but 925 is what I use on all my water tanks.

I am sure that if you can find an International Paint rep in your area he could look at your application and guide you in the right direction.

 

[pumphead]

Thanks for all the comments.

Our steam plant is actually mostly makeup water. We're now going to be recovering condensate from our Alky unit, and so this tank serves as a precautionary measure (in addition to other measures) to avoid process contaminating our steam.

 

[MJCronin]

pumphead....

There are companies that will supply a tank/pump combination for this specific corrosive service. They are commonly called "condensate recievers", replaced about every five years, and you would find them in college, hopsital etc district heating service.

Interesting, corrosive things happen when you combine the returned condensate with the softened make-up......

Common MOC are cast iron, heavy walled carbon steel, 304SS and epoxy coated CS.

See:

http://www.envirosep.com/dload/ECPL-S.pdf

for one...

-MJC