1000 gallon home made tank cause corrosion issues?

[sparke]

I just picked up a 1000 gallon tank very cheap.  I think is is made out of galvanized steel.  The tank is built just like a propane tank and is expertly made.  The previous owner said it was pressurized.  If I use this as pressurized hot water storage - will the galvanized tank cause issues with the rest of the heating system?  I know there will be corrosion issues at the fittings but what about the rest of the system?  My intention was pressurized storage but I am wondering if I should isolate the tank with a heat exchanger?  Any input is appreciated...

The first picture is a close up of the steel.  The prior owner was not sure if it was galvanized...




(broken link removed to http://i126.photobucket.com/albums/p83/sparkie68/New) Tank/121.jpg


(broken link removed to http://i126.photobucket.com/albums/p83/sparkie68/New) Tank/Picture115.jpg


To see link copy and paste the whole line...

 

[ewdudley]

I just picked up a 1000 gallon tank very cheap.  I think is is made out of galvanized steel.  The tank is built just like a propane tank and is expertly made.  The previous owner said it was pressurized.  If I use this as pressurized hot water storage - will the galvanized tank cause issues with the rest of the heating system?  I know there will be corrosion issues at the fittings but what about the rest of the system?  My intention was pressurized storage but I am wondering if I should isolate the tank with a heat exchanger?  Any input is appreciated...

The first picture is a close up of the steel.  The prior owner was not sure if it was galvanized...

[/quote]

Yes it's galvanized.

If it is kept above the dew-point the exterior fittings will not corrode exceptionally, exposed steel is exposed steel, the galvanized has nothing to do with it in this respect.

Inside the system the galvanizing layer will is pretty much inert, as it is intended to be.  The only reason you don't typically find galvanized buffer tanks in hydronic heating systems is because galvanized is more expensive and it is an unnecessary expense in an oxygen depleted envrionment.  

But in your case it's not an additional expense at all.  Nice score.


Cheers   --ewd

 

[stee6043]

I'm not sure I'd rely on someone telling me a tank was "expertly welded". Do you have a way to safely pressure test it prior to installation?

 

[sparke]

Thanks for the replies. The welding on the tank looks as good as anything I have ever seen. I have worked in paper mills, nukies, etc... Anyway my plan is to charge it to 20 - 30 PSI and let it sit over night. The same way one would test a plumbing system. Do you think that is sufficient? The prior owner said the tank had been used in a pressurized system but I still plan on testing it.

 

[in hot water]

If it was professionally manufactured it should have a data label or at least the manufacturers name. The gauge of the material and the types of heads (ends) are an indicator of the construction. Water tests are safer than air pressure, as can be demonstrated with a balloon.

Will it be located in an area where a rupture would not cause a problem

Brass fittings at the connection points would be a good idea.

hr

 

[peakbagger]

If there isnt a data label on the tank its not rated for pressure and your insurance company does not have to pay for any damage incurred if it ever lets loose. Someone with a mig welder can make great looking welds with minimal penetration. 20 to 30 PSI doesnt sound like much but when you figure out the kinetic energy, its a lot. Generally the tanks "oil can" pretty quickly when pressurized.

 

[sparke]

I am really not worried about the structual integrity of the tank. The welds and construction are solid. But for reasons mentioned I think I am going to use a heat exchanger and keep the tank unpressurized. How much efficiency is lost using a 30 plate HEX vs pressurized? I was really looking forward to a pressurized system.

 

[ewdudley]

If there isnt a data label on the tank its not rated for pressure and your insurance company does not have to pay for any damage incurred if it ever lets loose. Someone with a mig welder can make great looking welds with minimal penetration. 20 to 30 PSI doesnt sound like much but when you figure out the kinetic energy, its a lot. Generally the tanks "oil can" pretty quickly when pressurized.

It sounds like nobody can get the URL to work, if they did it would be clear to all that the tank is a conventional galvanized tank with domed ends and designed to hold many dozens of pounds of pressure. There is no opportunity for this tank to 'oil can'.

If by kinetic energy you mean potential energy, if you really did figure it out it would not 'be a lot' because in its application as a hydronic heating system buffer tank there would be no compressed gas in the tank.

If it ever 'let loose' it would be with all the drama of frozen pipe, again assuming no compressed air and no water above boiling temperatures.

Cheers --ewd

 

[Nofossil]

Looks like a normal pressure tank - domed ends, commercial construction. Where I am, I'd fill it with water and test to 30psi, then run it pressurized. I don't think you want to have copper threaded into galvanized, but otherwise it looks like it should be OK.

You'l have better luck posting links if you don't have spaces in the names of your folders and/or pictures. Just because Microsoft and Apple think it's OK to have spaces doesn't mean that it works in the real world.

 

[sparke]

I have tried every way possible to get the space out and when I re-paste the link it automatically cuts it out. Almost like the hearth.com only allows has x amount of space in the url... The link that is copied has no spaces in it. I used every differnt code photbucket offers and none of them work.

Anyway if you could see the tank in person you would see it is built as well as a commercial tank. Nofo - that is exactly what I had intended to do to test the tank. But I was getting gun shy after reading a few of the posts. I fell like I am back on track now. If I can't go with a pressurized system there is really no sense in changing out my home made tank other then gaining about 250 gallons. How big of an expansion tank do I need? (90 gallons)? I am lucky enough to know Chris from Floor Heating Systems (also Garn rep) who will hopefully help engineer the system. He helped me with the piping on my home made tank and came up with a very clever design to get reverse flow through my HEX.

One more thing I should mention about the tank. You can't see in the pic but one end is concave. In other words the bell end is inverted into the tank. Any idea why they would do this? My first thought is they did it to shorten the length of the tank. But since the tank is custom made they could have achieved that in other ways...

Thanks for all your input guys, I appreciate it.

 

[Chris Hoskin]

I would guess that the concave end is meant to be the bottom of the tank when standing vertically. The dome shape, of course, resists oil-canning much better than a flat bottom. It is probably worth testing for leaks, etc. , but it certainly looks like a great tank for a pressurized set up - especially if you can stand it vertically, but either way. I agree with EWD, nice score!

 

[sparke]

Was a heck of a score $200. I could not pass it up. Right now I am in the process of taking apart my home made tank. Kinnda makes me sad but I know the new tank will be worth the effort!

 

[mwk1000]

I agree , test it yourself to remove the FUD and go pressurized. Make sure it sits somewhere where an insurance claim will not be in your future even if it did leak.

 

[Nofossil]

Make sure it sits somewhere where an insurance claim will not be in your future even if it did leak.

I pretty much assume that anything with water in it will leak eventually. I try to design installations to anticipate and minimize the consequences.