I moved a response to a different topic by member "Berlin" to a new thread because this is very interesting and may not have been fully appreciated in the prior thread.
Berlin stated:
"the problem w/ metal brushes on stainless chimneys/liners flex or not IS real. It will damage the chimney, not as fast w/ wood as with fuel oil/coal due to less acidity, but it will cause a shorter lifespan nonetheless. Bits of steel become embedded in the protective oxide layer of the stainless which allows a pit to form like a cancer. some alloys are more resistant to this than others, 316ti being one, but damage is still being done. btw, it has nothing to do with actually “scraping” away at the liner itself, rather, as i mentioned, the embedding of non-stainless steels into the exterior of stainless steels allows corrosion to start on an otherwise healthy chimney thus giving it a shortened lifespan… and it ends up looking like swiss cheese. Coal is especially bad for stainless chimneys/liners because the flyash naturally contains bits of iron, as well as higher acidity etc. This is why Coal should not be used with stainless unless the user has the expectation that the liner/chimney won’t last more than a decade, and likely not even that. There is a very good thread (on the Nepa coal website) on a stainless flex 316ti (the MOST corrosion resistant alloy) being used with coal; it collapsed after less than 5 years and looked like a slinky. That is what happens when iron particles allow pinholes to begin on “stainless” steels in a corrosive environment. "
At first, I thought, well, maybe, opinions are like a@#holes (borrowed from Clint Eastwood). But, then I did some reading and found this:
"Contact Corrosion
This combines elements of pitting, crevice and galvanic corrosion, and occurs where small particles of
foreign matter, in particular carbon steel, are left on a stainless steel surface. The attack starts as a
galvanic cell - the particle of foreign matter is anodic and hence likely to be quickly corroded away, but
in severe cases a pit may also form in the stainless steel, and pitting corrosion can continue from this
point."
Before cleaning my stainless chimney I inquired about whether to use a poly or steel brush. There were various opinions in this forum, but I also asked Selkirk Metalbestos since they made the pipe I own. They didn't have a problem with me using steel wire.
I tried both. I think that the steel cleans better, but I only used it on occasion when I thought plastic didn't do the job.
I guess I will be contacting Selkirk again to see what they have to say about this. Fortunately, I did keep a copy of their response to my original question, so my warranty should be in tact.
I can't be sure if this really is a problem for wood burners, but it is certainly is worthy of further discussion. If anyone has SS pipe cleaned with a metal brush over a long period of time, please comment.
Once again, I have to thank every member on this site who takes the time to share their information and opinions.
Berlin stated:
"the problem w/ metal brushes on stainless chimneys/liners flex or not IS real. It will damage the chimney, not as fast w/ wood as with fuel oil/coal due to less acidity, but it will cause a shorter lifespan nonetheless. Bits of steel become embedded in the protective oxide layer of the stainless which allows a pit to form like a cancer. some alloys are more resistant to this than others, 316ti being one, but damage is still being done. btw, it has nothing to do with actually “scraping” away at the liner itself, rather, as i mentioned, the embedding of non-stainless steels into the exterior of stainless steels allows corrosion to start on an otherwise healthy chimney thus giving it a shortened lifespan… and it ends up looking like swiss cheese. Coal is especially bad for stainless chimneys/liners because the flyash naturally contains bits of iron, as well as higher acidity etc. This is why Coal should not be used with stainless unless the user has the expectation that the liner/chimney won’t last more than a decade, and likely not even that. There is a very good thread (on the Nepa coal website) on a stainless flex 316ti (the MOST corrosion resistant alloy) being used with coal; it collapsed after less than 5 years and looked like a slinky. That is what happens when iron particles allow pinholes to begin on “stainless” steels in a corrosive environment. "
At first, I thought, well, maybe, opinions are like a@#holes (borrowed from Clint Eastwood). But, then I did some reading and found this:
"Contact Corrosion
This combines elements of pitting, crevice and galvanic corrosion, and occurs where small particles of
foreign matter, in particular carbon steel, are left on a stainless steel surface. The attack starts as a
galvanic cell - the particle of foreign matter is anodic and hence likely to be quickly corroded away, but
in severe cases a pit may also form in the stainless steel, and pitting corrosion can continue from this
point."
Before cleaning my stainless chimney I inquired about whether to use a poly or steel brush. There were various opinions in this forum, but I also asked Selkirk Metalbestos since they made the pipe I own. They didn't have a problem with me using steel wire.
I tried both. I think that the steel cleans better, but I only used it on occasion when I thought plastic didn't do the job.
I guess I will be contacting Selkirk again to see what they have to say about this. Fortunately, I did keep a copy of their response to my original question, so my warranty should be in tact.
I can't be sure if this really is a problem for wood burners, but it is certainly is worthy of further discussion. If anyone has SS pipe cleaned with a metal brush over a long period of time, please comment.
Once again, I have to thank every member on this site who takes the time to share their information and opinions.
