Electrolysis Tank Failure?

solsean

Saw something?  On a recent inspection found an atmospheric 700 gallon, 304 stainless tank leaking from the walls.  Upon putting a meter on the tank and a reliable ground, found 6 mV on the tank wall.  I have a Rheem electric water heater with pre-heat from the solar buffer w/, recirc operation during solar collection, electric boiler primary circuit as backup to heating system($03.5/kwh off peak), high mass infloor w/O2 barrier, injection heat from solar buffer on secondary distribution loop, Tekmar 363 making everything talk.

Everything grounded, "to code"? 

Mark Eatherton

HMMmmmmm....

I am not a metalurgist, but I'd suspect poor water quality. How much chlorides in the water? That is the one thing that can cause chloride stress corrosion in stainless steel.



Electrolysis, to the best of my knowledge, is the plating out of metals, and the flow is usually from the lesser noble metal.



You might run it by Metro Dave and see if he's run into it.



ME

meplumber

I agree with ME.

I saw something similar on a 304L tank that was subjected to an over active water softener.

Larry Weingarten

304 vs 316

Hello:  Just to add in, I've had only trouble with 304 and hot water.  316 holds up much better in the waters I have in Central California.  As to the stray current, look around and see if there are wires running close to metal piping.  It can act like a crude transformer and induce current into the pipe.  Code may be enough for safety, but isn't as concerned about equipment longevity.



Yours,  Larry

solsean

More info

So I have not been able to reliably check the chlorides but am very suspect of them being the issue.  The house is on a well that fills a 2,000 gallon cistern before becoming availble for usage so I would think they would evaporate off.  The tank is filled twice a year so ther is new water being introduced.  Beyond spa test kits what is the best way to test for chlorides?  I have spoke with manufactures and chlorides were mentioned.

hot_rod

try this site

for more info if you want to buy a test kit.  Or contact the nearest water treatment company, like a Culligan.  They should have a means to test for chlorides.  Often it is caused by a malfunctioning softener or city water treatmeant, neither of which you have?



http://www.ky.gov/nrepc/water/wcintro.htm



Maybe contact a metal fab company and ask them how they test for stainless attacks. 



 Our wall buddy Perry would know if he is still around, search the archives for some of the info he has posted in the past on metal and corrosion.



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