Coalpail.com Forum

I have seen flyash corrode stainless steel.
I have read flyash corrodes copper.
Does flyash corrode aluminum?

Would like to find a chimney cap that is not going to rust out in a few years.
Wondering if aluminum mesh instead of steel or copper would last longer.

I'm using a stainless steel chimney cap. It's a few years old now, seems to be holding up very well. The first cap a bought was just regular tin metal, it disintegrated in two years. I'm not sure about aluminum.

I bought a Metal-Fab chimney system about 8 years ago. I’ve been through 2 caps already. The product description says it’s stainless and claims it’s good for coal. It’s crap!!! I had to fight with the company to get replacement caps under the warranty. Coal gas is corrosive when mixed with moisture so anything exposed to the elements will not last that long.

Does anyone have some flyash they can put in a used aluminum can with some moisture, see if it gets eaten?

I had some aluminum heat protection near my stainless chimney and it rotted little holes thru it. I had a stainless cap and I think it was after 3 years of coal the wind broke it off. I didnt notice any pitting on the cap but it was destroyed from the wind and the fall to the ground. To be fair, that stainless cap had seen a lot of wood burning and may have been protected from the creosote on it. Ive never used copper.

Its the nature of the beast, as they say.

I wonder if powder coating would help?

I powder coated many years and did some stuff for myself too. I think it would depend on the type/brand of paint and it seemed like even the color sometimes for how tough it was. There were a few light colors you could hardly chip with a hammer.

We used to paint boat trolling motors by the thousands and when it was motors that were going to be used for salt water, it got 2 coats. The 1st coat was a zinc rich primer. That was put on and cured and then a black wrinkle over that. Without some thought I cannot remember the brand of black wrinkle but I will remember at some point. I think the zinc primer was the most important part. They do sell it in spray cans and those cans are quite heavy. I use it for outdoor stuff and some car parts before the paint.

I have a problem with heights but i have always wanted to paint my chimney flashing with that zinc spray. Someday I will feel brave again and go up there and spray it or not

AL29-4C Stainless Steel will last the longest. Al alloy wil corrode in no time when subjected to wet fly ash.

I have a buddy that made an aluminum ash pan. Yes, it corrodes. He had to replace it after 4 or 5 years.

As others have mentioned aluminum will corrode. Copper will also.

A few years ago i got creative and experimented with #12 copper wire to hold the chimney cap in place. The cap was SS and held up but its screen and legs to fasten to the pipe were apparently lesser quality as they corroded to nothing after many years. I have lots of scrap wiring in a box in the shop so i thought I'd fashion something out of that to hold the cap in place. I got two seasons out of it before the copper became brittle and broken.

I replaced the cap last year with a cheap $10 one from TSC and that cap wasted away to rusty flaking tissue paper consistency in one year! Had to get a new one this year.

The chimney itself is a 6" double wall SS installed in January 1993. It is still in great shape, no corrosion at all. The outside of the highest section of pipe is discolored (probably from the caps) but is not corroded at all.

I've also got an ash pan that Freddy made a few years back that is still in great shape...no corrosion. Not sure what gauge you used Freddy, but it is certainly heavier than the oem!

Aluminum does funny things. I gave a buddy of mine a 283 Chevy engine. He took it apart and cleaned everything up. Only problem was he left the pistons and rods soaking in a bucket of Tide. When he pulled out the first rod and all that was left on it was the wrist pin he knew he had a problem.

Here what aluminm does when it gets aquainted with mercury.

That is pretty freaking cool!!!

THAT Aluminum Vs. Mercury looks like that "Mercury" is either heavily contaminated with Gallium or entirely replaced with Gallium...

But as Coal is a form of marine sedimentary rock it is "contaminated" with a certain quantity of "Lime" (Calcium Carbonate) which is converted to Calcium Hydroxide at combustion temperatures, and Calcium Carbonate is indeed corrosive to Aluminum.

Hell,even I corrode! Honor the Animal that You're working with and protect against it's corrosive properties! You could get in touch with your Inner Mad Scientist and experiment with both base metal and flue appropriate protective coatings.....