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Brand new Saf-T Pipe flue has lots of rust on inside - is this normal?

Post in 'The Hearth Room - Wood Stoves and Fireplaces' started by tradergordo, Jul 17, 2006.

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  1. tradergordo

    tradergordo Minister of Fire

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    My flue pipe just arrived today, its one 4 foot length, and one two-part telescoping length of Heat-Fab 6" standard black Saf-T Pipe. I didn't really know what to expect, but the pipe looks fine and clean on the outside, was wrapped in brown paper, and is pretty rusted on the inside. I am just wondering:

    1) Is this normal, and if so, how long do these flue pipes typically last?

    2) Should I apply anything to the inside of the pipe for further rust prevention? If so, what? (for example Home Depot sells "High Heat" Rust-Oleum that resists heat up to 1200 degrees F but I have no idea if its appropriate to use on the inside of my flue pipe?

    Attached are pictures just taken!

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  2. MountainStoveGuy

    MountainStoveGuy New Member

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    The stainless they use on the inside of pipes isnt the highest quality, some brands are better then others. I dont know your pipe well enough to comment on the quality, but i would not take it in that condition, you should not have to paint the inside of your pipe to protect it. Take it back to the place you bought it.

    edit: wait thats black pipe, shure it will rust, that pipe has obviously gotten wet. I didnt look at the first photo, the second photo looked like double wall. sorry, your single wall will eventually rust out, but it will take some time. The rust on there now doenst look that bad, clean it up or take it back.
  3. tradergordo

    tradergordo Minister of Fire

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    Its made from 22-gauge cold rolled steel. Its not stainless. My understanding is that most flue pipe is not stainless (come to think of it, I've never seen stainless flue pipe in any stove shop or hardware store before, only the chimney pipe is stainless).
  4. MountainStoveGuy

    MountainStoveGuy New Member

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    did you see the second half of my statement? black pipe is not stainless, and it will rust if wet. Double wall black (that is what i misstook your second photo for) has a stainless lining. If your pipe happend to be old stock, i would expect rust. It looks like surface rust and shouldnt hurt anything, but it wouldnt hurt cleaning it up or taking it back to the dealer you bought it from, have you called your dealer?
  5. webbie

    webbie Seasoned Moderator Staff Member

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    They use regular steel on that pipe - not protected in any way, and it was my experience that it would get some rust on the inside while sitting in my warehouse. I think it will be fine.
  6. elkimmeg

    elkimmeg Guest

    Congrats for buying a more quality 22 ga. That surface rust in this humidity is normal after you bring your stove up to 500 degrees the rust is a non factor. You are fretting little things not to be concerned about
  7. Corie

    Corie Minister of Fire

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    Exactly.

    The instant non-coated mild steel is exposed to the atmosphere, it will begin to oxidize. That rust you see if you absolutely no consequence. All of the hot rolled pieces of steel I have sitting around here display some degree of oxidation.


    Also, there is stainless steel single wall stovepipe available, although it is technically made to be chimney liner. Hart's Hearth sells it online, and although it is rather costly, it will probably be the last stovepipe you ever have to buy.
  8. begreen

    begreen Mooderator Staff Member

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    Like Elk said, 22ga is a really stout pipe. A little rust on the inside will soon be history. Not to worry.
  9. tradergordo

    tradergordo Minister of Fire

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    Thanks guys - that's why I came to the experts!
    Now - I assume that in the off season, the rust is going to form every year. Back to my original question - should I try to do anything about it (like a new coating of high temperature rust-oleum every year or two) or should I just leave it be? Do any of you guys do anything to the inside of your stove pipe besides a normal brush cleaning?


    (I'd also love to know just out of curiosity, an approximate expected lifespan on this stuff - obviously there are a lot of factors - but what has your experience shown?)
  10. webbie

    webbie Seasoned Moderator Staff Member

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    Just keep the outside painted and rust-free. The inside should just be brushed.

    In my experience, it should last from 5-10 years in wood burning....perhaps to the longer end if everything is OK (not near the beach, etc.)
  11. babalu87

    babalu87 New Member

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    I dont know if this will help with anything other than that grey stuff between my ears but after I cleaned out the inside of the stove I put a big bag of that stuff that says DO NOT EAT you see with packaged electronics.
    Hopefully that will absorb any moisture that finds its way into the stove and maybe even the surrounding pipe.

    BTW a nice coating of creosote will hide that rust :)
  12. tradergordo

    tradergordo Minister of Fire

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  13. begreen

    begreen Mooderator Staff Member

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    Gordo, your mileage may vary. I just took down our system. It had 24 ga, single wall black pipe that was at least 15 yrs old and in great shape. I know it has burned 2-3 cords per year for the last 12 years.

    Here is another odd thing. The pipe went straight up to a metalbestos collar and exterior class a chimney of about 8 feet. I had it cleaned the first year and have inspected it every year since. Just removed it and even though not cleaned in 10 years, it is still exceptionally clean, virtually no build up. I don't recommend this to anyone, but I have easy access to the stack and was just curious. It's sure a testimony to clean burning Jotuls. Several cords have been fir and hemlock which should be notorious creosote producers. But we always try to burn only dry wood, a little on the hot side and rarely damper down the fire and let it smolder. That and a mild climate seem to work well for keeping creosote in check.
  14. tradergordo

    tradergordo Minister of Fire

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    Wow, that is impressive. What state are you in? Is it a very dry climate?
  15. suematteva

    suematteva New Member

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    Agree with begreen...Another thing that will affect your mileage is where the installation is...Basement humidity is higher summer rust etc..may make a difference also...We put 5 cords of hardwood (1/2 cord of poplar begining & end of season) through ours minimum 18 mths dry..clean once a year between a cup an cup and half of creosote....inside of the single wall there is nothing...burning a non cat hearthsone mansfield in basement...I believe our pipe is 22 gauge..this will be the 4th season and we check every year and guestimate is at least 10...maybe 15 years of life...Picturing stainless in our installation...reminds me of the kitchen...IMO
    good luck
  16. elkimmeg

    elkimmeg Guest

    My gestimate is 22 ga. steel welded seams will last at least 1/3 longer if not more I say please post your results in 2024
  17. MountainStoveGuy

    MountainStoveGuy New Member

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    If you want to go to something else, i would recommend you buy the interior double wall that is already black on the outside and stainless on the inside. Then you will never have to mess with it. Including having to paint stainless single wll.
  18. babalu87

    babalu87 New Member

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    Ah MSG but then you lose all that "free heat" that emmits from the single wall pipe.

    Thats why I ran mine as tight to the ceiling as I could before going out and up the outside.
  19. MountainStoveGuy

    MountainStoveGuy New Member

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    Sometimes that free heat comes at a price, if you have a long run of it it will actually rob the chimney of heat that it needs to draft. The more efficient the stove the more this comes into play.
  20. babalu87

    babalu87 New Member

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    Understood MSG

    I think I wound up with a great balance
    About 3 feet of pipe inside and the other 21 feet outside and it drafts great.
  21. begreen

    begreen Mooderator Staff Member

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    WA state, Puget Sound region. Wet in winter, dry in summer.

    7 ft. singlewall, 8 ft. class a., strong draft (have to run with a draft damper after it warms up).
  22. tradergordo

    tradergordo Minister of Fire

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    I had the same thoughts regarding the "free heat" from the single wall which is specifically why I also did a pretty big (9 foot) single wall run straight up inside the house (cathedral ceiling). I am aware of the potential drafting issues but I do not think it will be a problem to tell you the truth - mostly because my run is completely straight (no angles, elbows, or tees whatsoever). If draft is a problem I can always switch at least part of the flue over to the double wall stove pipe later.

    As for painting stainless steel - no way! It looks great unpainted.

    For now I'm just going to keep what I have and see how it all works out.
  23. MountainStoveGuy

    MountainStoveGuy New Member

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    short runs of single wall dont create a problem, i consider short anything less then 6'. There are other factors, it might appear ro work fine, but if you have a lot of pipe on the exterior it might not work fine, the cap would plug faster, the exposed pipe would gunk up faster etc. it hard to say that something is true all the time. For example, 9' of single wall on a VC .8 gram per hour stove, with 8' of class A sticking out of the roof would not draft as well if the same install had 3' of pipe on the outside. When you have a large run of pipe on the exterior its critical to maintain hot flue temps.
  24. Corie

    Corie Minister of Fire

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    Talking about single wall pipe and such. My girlfriends family has a Russo connected to 12 feet of single wall and then 6 feet of Class A up through the tall cathedral ceiling. Never in my life have I experienced a stove with a stronger draft than this.

    If you leave the ash pan door open for more than 10 minutes, no matter how big or small the fire was, you will be coming back to a flaming glowing monster of a coal bed.
  25. MountainStoveGuy

    MountainStoveGuy New Member

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    perfect example of a good single wall installation.
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