Thread: "Hostile" Chimney Fire

I have only run across this type damage once before.

It may be difficult to see, but the stainless is discolored - which was the first hint something was amiss. The closeup shot shows damage from corrosion.

Just thought I would share these for anyone who may have not seen this type damage to a stainless liner.

Jim

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Be careful Jim, that exterior corrosion alone does not make it prima facie evidence of a chimney fire. There was a class action lawsuit filed against several manufacturer's of factory built solid packed chimney for failures. It seems the insulation contained a lot of chloride ions, which, formed HCL if it got wet. The method of forming the male end crimp of these brands allowed moisture to enter the insulation pack, which did two things: it reduced the R valve, thus creating hot spots, and two, formed HCL, which attacked the steel. Most of these mfrs. use 430 or 444 stainless, which may resist rain ok but not strong acids. The term "stainless" is an unfortunate one that gives the impression of Super Man's cape.

I suggest the chimney be identified and the manufacturer contacted. It may be out of the settlement period in which case you would have to channel it as any other warranty claim.

To ascertain if this was possibly caused by a chimney fire, you need to visualize the inner lining. There will be zones of discoloration but more damming is the presence of rust in the stainless inner liner. When stainles steels are heated above about 1,380F, they become susceptible to what is known as forming chromium carbides or intergranular corrosion. The stainless steel is then no longer "stainless" so it stains or rusts. See my attached photos from a witnessed chimney fire.

Think of factory chimney like a fuse--it protected the home from burning down so now it needs to be replaced. This is usually an insurable loss. Most mfrs. will consider the warranty void after a chimney fire but reinstate it once the fireplace has been thoroughly inspected (Level II or III) and the chimney replaced.

In Jim's case, this is a clear cut Red Flag for a Level II inspection. Irregardless, the chimney must be replaced before being used. However, if it was from an unfriendly fire, the insurance may pay for it. If it is from a manufacturing defect, the mfr. may or may not pay for it. The simplest way to ascertain which it is would be from a Level II inspection. If there is no sign of a creosote fire in the flue, no damage to the inner sections, joints, and no signs of rust or corrosion, then it probably is from chloride attack. Either way, the mfr. should be involved.

HTH,
Bob

The best remedy to any chimney fire is regular maintenance. This should include twice yearly visual inspections, proper flue cleaning (professionally), burning only well seasoned dry wood, proper ventilation, damping the fire properly, covered wood storage and clearances to combustibles. There are others.

The local fire hall has lots of good information on the do's and don'ts.

I have had my stainless chimney system for 20 years and had them all replaced twice, just for safety sake. And only one small fire.

T.Neyedli
www.alphahomeinspections.ca

Originally Posted by Bob Harper

Be careful Jim, that exterior corrosion alone does not make it prima facie evidence of a chimney fire.

Thanks for that, Grey Beard. I'll be on the lookout for the killer chlorine in the future.

My photo does not show it but there was a discoloration halo - tints of blue and brown, that makes me lean towards the chimney fire. Chlorine would not cause that effect, would it?

Too bad I can't do the Level III and take it apart! Drats, Bob gets all the fun!

Jim

Do I see two different vents there? If so, I would question whether they are rated for use with each other, not to mention rated for use with the firebox.

Just a wandering thought.

Eric, a common fire investigative technique is to re-construct the order in which each component was in the original installation. Here, we have the outer galvanized casings (in the rear) alongside the inner stainless steel liners. This way you can correlate what happened where. Did the inner liner contain it or did heat, smoke and gases escape into the annular space? Did the lances hold the inner liner sections or fail? Was there a hot spot so intense it cooked away the galvanized coating on the inner surface of the outer casing? BTW, the chimney did its job and contained the fire. Now, it must be replaced as per the warranty and is an insurable loss.

No, these pipes are all from the same fireplace just laid out for inspection. Still it's good you thought to question it Eric.

FYI, I'm getting really busy so ya'll won't see me chiming in as often.
Bob