Flexible stainless steel exhaust flex tubing as chimney liner???

[wowchad]

I'm in trucking parts business and can get .018-.022 gauge 302 SS exhaust flex at cost. Is there any reason why that wouldn't work as insert liner?
I think it's pretty thick compared to the standard chimney liner I've seen...is 302 a lesser grade stainless?

 

[EddyKilowatt]

I'm no expert, but I noticed that the stainless for wood smoke liners is surprisingly exotic -- 316 with extra titanium, and stuff like that. Something to do with surviving a chimney fire, which ordinary stainless may not be up to. There's also quite a brew of corrosive stuff in wood smoke, and more likely to be condensation in a chimney compared to a big rig stack.

Now with this bump, maybe we'll hear from the experts... good luck.

Eddy

 

[Corey]

You're on the right track - the official explanation that I have heard is "The added titanium prevents the carbon (specifically chromium carbide) from precipitating at the grain boundaries during elevated temperature service" That is a fancy way of saying it helps the steel remain corrosion resistant at high temperatures - generally above 1500F.

So, a couple things come into play here. How many times does your flue see 1500F and higher? and would the extra thickness of your steel make up for some of the reduced corrosion resistance. It's hard to say. I suspect 1500F would probably only be seen during a chimney fire - unless you have the liner fully insulated. As for the extra thickness - again hard to say, since this deals with grain boundary corrosion of the steel, an affected area could be totally corroded away, while steel an inch away - in an unaffected area - could be in good shape.

While, I can't specifically endorse the idea, if you did go ahead with it, I would think it would be wise to keep an eye on the hottest sections - especially coming right out of the stove - for any signs of corrosion. I also have to ask - can you get this in 6" diameter or are you planning to run duals all the way up the chimney - possibly with chrome stacks on top??

 

[DriftWood]

304 , 316, 316ti Stainless Steel are wood fuel grades. I wouldnt use anything else. You dont need any suprises in the middle of the night.

 

[theheatelement]

Plus.... what might happen if you have a chimney fire and your insurance asks to see whether or not it was an approved liner... that could mean the loss of thousands of dollars.

 

[BrotherBart]

The biggie is that the joints in truck exhaust flex aren't welded or crimped. Nobody is concerned if it leaks at the joints before it blows out the top of the stack. The stuff leaks like a sieve but you just never see it. Don't do it. Been there, thought about it and bought a liner.

BB - Hauled a bunch of veggies on backhauls from Bakersfield to Dallas and used to run a truck shop.

 

[boostnut]

I knew this would come up eventually. I'm in the heavy equipment exhaust business (generators, barges, mining trucks and everything between). The liner you're likely refering to is 304 s.s., never seen or heard of 302. Interlocked flex is typically used on over the road trucks and, as you said, is much heavier than the typical stove liner material. Start with some prices. I looked into this just over 2 years ago when i installed my insert. I found that (at that time) there was very little cost savings after factoring in the freight costs. My boss, the company owner, decided to use our stock 6" 304 s.s. interlock flex with his insert, I did not. He has been running it for 2+ years, no problems to report. Btw, he had a chimney fire last year. Would I use 304 interlock if i had it to do over again? Hell yes! Its more durable and flexes thru the masonary chimney smoke shelf area easier. As stated earlier, its good to about 1600 degrees. If you're seeing that kind of temp you'll have a number of other issues to address long before. Just my $.02

 

[elkimmeg]

First of all all chimney liners must be HT 2100. Which means it can withstand chimney fires that approach 2100 degrees

1600 degree range is below many chimney fires temperatures and just plain is the wrong heat range by a wide margin

 

[TMonter]

First of all all chimney liners must be HT 2100. Which means it can withstand chimney fires that approach 2100 degrees

HT2100 means it will contain the fire but the liner will be a loss afterwards.

 

[wowchad]

After looking closer into this the price is higher and your all very right, it's not worth the risk.
Interesting topic though
Well good night all, I'm going hunting in 5 hours and if we get deer, monday I get to cut up some nice wood...oak tops.

 

[Gooserider]

Surprised Elk failed to mention the key point from where he sits - Truck exhaust pipe is NOT UL LISTED or approved for the application - no UL label at least in theory means that it can't pass an inspection, and if there were ever a fire the insurance Co. could get sticky about paying off due to the use of an unlisted product...

Gooserider