Wood boiler failures

Steve Ebels

Here's one that has me stumped. A friend of mine has an outdoor wood boiler constructed of stainless steel. He has had numerous failures/perforations on the welded seams of the boiler itself and the seams of the water jacket door. The manufacturer has told my friend that he has a high concentration of sulfur or sulfide in his water. He has sent his water in to several labs and all they have told him is that he has an elevated level of sodium in his water from the softener/tanin unit he has installed to treat his domestic water.


Any ideas what could be causing these failures??

Dan Peel

Sulfates

Sodium sulfate, sodium molybdenate and a few other derivitives are common to open systems for the control of stray O2 and initially coating inside surfaces. Too much of a good thing can be extremely corrosive to the 409 stainless used in most SS wood boilers. The 409 is actually a magnetic stainless with expansion and other thermal properties similar to those of mild steel -far less active than the food grade 300 series. Another chemical which attacks 409 is chlorine. When in doubt use DI water. Enjoy....Dan

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hr

Stainless

As Dan mentioned there are dozens of grades and alloys of stainless. The application and weld method and quality of workmanship are very critical. We learned this mid eighties when stainless indirect tanks flooded the market. It took some unfortunate "in the field" R&D headaches before the manufactures got a good handle on stainless manufacturing of pressure vessels thay under go such rapid and wide temperature swings.

Certainly the treatment and fill water needs to be addressed. The inhibitor chemicals need to be formulated to the application.

Sounds like you may have a few different contributing factors.

hot rod

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Steve Ebels

What's

DI water?? Distilled? RO'd?

Mike T., Swampeast MO

De-ionized

I believe.

Dan Peel

Zactly..



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Steve Ebels

And just where

Pray tell would a guy out in the sticks like me, come up with roughly 160 gallons of DI water. Do plumbing distributors have access to this or should I call Culligan or the like?? Also, what different about DI water? Is it inert or non-reactive to everything?

Dan Peel

Hey Culligan man...

That's where I go and get it. They call it de ionozed and demineralized (basically water with only the wet left in it). Our local outlet has a bulk program - check if they deliver in bulk. Any time you're working with questionable water quality it's great comfort to put the receipt for purchased water into the finished job file. Enjoy.....Dan

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PJO

One more thought...

about DI water. It has no buffer against pH adjustment and may be a low pH itself, which means if the slightest tendency is towards an acidic environment it will drop. In other words, if you have to add a little bit of local water to top it off, be sure the pH is okay before you walk away. Some inexpensive test strips will ease your worries.

It's improbable, but not impossible, that a few gallons of "top-off" would make a difference.

Just my thoughts. Take Care, PJO