Stainless Steel or Galvanized

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Adamiscold
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Post Mon. Aug. 18, 2008 8:54 am

I see piping for coal stoves is offered in both types and for the Simpson brand
**Broken Link(s) Removed** they both come with a lifetime warranty, is one better then the other? Also looking at stove pipe
**Broken Link(s) Removed** they seem to say for wood only. What type of stove pipe do you use for a coal stove or will any stove pipe due or does it need to be regular Class A pipe?


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coaledsweat
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Post Mon. Aug. 18, 2008 9:09 am

You should not use galvanized smoke pipe on a solid fuel appliance. From the appliance to the thimble, use black steel smokepipe. For a metal chimney you must use a double wall insulated high grade stainless steel, 304 is good, 316 is better.

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Adamiscold
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Post Mon. Aug. 18, 2008 10:11 am

You should not use galvanized smoke pipe on a solid fuel appliance. From the appliance to the thimble, use black steel smokepipe.


What brand name black steel smoke pipe supports coal and where do you find them?
For a metal chimney you must use a double wall insulated high grade stainless steel, 304 is good, 316 is better.
On here
**Broken Link(s) Removed** for all coal supported double wall Class A 6" chimney pipe is made of the following;
Simpson and Metal-Fab use on their outer walls 430 G-90 Galvanized Steel and 430 Stainless on the inner wall at different thickness, both supported for use with wood, oil, and coal. SuperPro uses 304 Stainless Steel on the outer and inner walls but it says it's only supported for wood use. Neither Security Chimneys or Metalbestos show what type of metal they use.

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Richard S.
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Post Mon. Aug. 18, 2008 2:40 pm

coaledsweat wrote:You should not use galvanized smoke pipe on a solid fuel appliance.
Why not? That's standard installation forever on any coal furnace in these parts. The pipe we have was the same one purchased 25 years ago to the best of my knowledge. The only issue with the galvanized is if you let the furnace go out every year it tends to rot away pretty fast. Roughly 5 to 10 years if you're lucky. Just check for weak spots every year and if you find one replace it all. Should also note the pipe we have is some pretty heavy gauge stuff and there is no elbows which seem to rot out the fastest.

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coaledsweat
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Post Mon. Aug. 18, 2008 2:55 pm

The zinc used to galvanize can easily come off the pipe if it is overheated and zinc is a very toxic heavy metal. If it gets hot enough it creates an extremely poisonous gas (this is why you need very good ventilation when welding galvanized). I have galvanized on mine currently, but when it comes time to replace it I'll go with black. I'm not sure where I read about it but IIRC it was on a stovepipe manufactures website. I'm not trying to scare anyone nor suggest that you must replace the pipe now or die, just that it isn't the best for solid fuel applications due to the possibility of very high temps with a solid fuel appliance. Years ago I had some galvanized and overfired the boiler until the pipe went orange, when it cooled it looked very different. It was covered with rust within a week, obviously the zinc was gone at that point.

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Post Mon. Aug. 18, 2008 4:18 pm

What coaledsweat said. Use the regular black stovepipe for venting to the chimney. Any hardware store will have it available in 8" or 6" depending on your need. If you're unsure you could go to any shop that sells heating supplies or coal stoves and they will tell you the same thing.

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Richard S.
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Post Mon. Aug. 18, 2008 4:21 pm

coaledsweat wrote: If it gets hot enough it creates an extremely poisonous gas .
Well there is no concern there with a larger boiler. Most of the time I can touch the pipe and even when its firing full bore I can still touch it quickly without getting burned. I don't think it would be possible to fire a Van-Wert to get it that hot. How hot does it need to get before it starts getting toxic?

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coaledsweat
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Post Mon. Aug. 18, 2008 4:44 pm

Zinc is toxic to begin with, the problem is if it doesn't stay on the pipe. It can come off in a fine powder though once overheated, it can be picked up on your hands if you touch the pipe or perhaps become airborne. Either way it can be ingested and heavy metals reek havoc on the brain and central nervous system. The only way to remove them from your body is chelation. As you say, with your stoker the pipe may never approach temps where it could become an issue. However, hand fired units are not that hard to goof and cook it up.

I'm not suggesting everyone run out a replace their existing galvanized, but because the stovepipe is removed for service fairly frequently, just use caution when handling used galvanized particularly when overheated and replace it with black when the time comes. That caution amounts to not eating, smoking or putting fingers in orifices prior to washing ones hands. It can't be absorbed through the skin to my knowledge, it must be ingested into the body.

I have no idea at what temperature it starts to give off the gas, I'll see what I can find.

Here is a link to the effects if it does gas off.

https://en.wikipedia.org/wiki/Metal_fume_fever


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coaledsweat
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Post Mon. Aug. 18, 2008 6:01 pm

Here you go, I guess the temperatures are a lot lower than I thought. The issue is the boiling point of zinc
(it melts at 787*F and boils at 907*F, I'm still looking for the off gas temp) is lower than the melting point of steel. I know Richard and most old time coal people could run their galvanized until there dead and gone and never have to worry about it. I just don't want some newbie that may fire on wood/overfire/whatever their stove with a child's bedroom vented directly above and have profound problems/health issues that are difficult to diagnose/treat because of it. The chances are small, but if its one in 10 million kids that doesn't get sickened because of this thread its worth it. Heavy metals accumulate over time in the body and us old buzzards suck it up and adapt, a child's mind and body takes a significant hit when exposed. Zinc is highly suspect in Alzheimer's too.

"The process of hot-dip galvanizing results in a metallurgical bond between zinc and steel with a series of distinct iron-zinc alloys. The resulting coated steel can be used in much the same way as uncoated. Galvanized steel can be welded; however, one must exercise caution around the resulting zinc fumes. Galvanized steel is suitable for high-temperature applications of up to 392 °F (200 °C). Use at temperatures above this level will result in peeling of the zinc at the intermetallic layer. Galvanized sheet steel is commonly used in automotive manufacture to enhance corrosion performance of exterior body panels of some models."

https://en.wikipedia.org/wiki/Hot-dip_galvanizing

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Post Mon. Aug. 18, 2008 7:42 pm

Wow 392F is not that hot.I don't know of any old oil furnaces that have that low of a stack temp!
I also noticed that galv tends to peel on the inside so I came to this thread looking for 316 SS
DON

I did find some 22 GA online I wonder how long that will last(black).Pricey though.

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Post Mon. Aug. 18, 2008 9:28 pm

Here is a case study in heavy metal poisoning.

"HEAVY METAL poisoning is almost always misdiagnosed and not treated. If you KNOW you have been exposed to possibly harmful metal dust, fumes or vapors, INSIST on being tested for metal poisoning and explain why.

THINK when you are working. Consider the repercussions. Be safe, live long."

http://www.anvilfire.com/iForge/tutor.php?lesson= ... fety3/demo

Everything you always wanted to know about zinc but were afraid to ask. Not for the faint of heart.

http://www.inchem.org/documents/ehc/ehc/ehc221.htm

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Post Mon. Aug. 18, 2008 10:46 pm

The reality is they have changed the process and make up of the current galvanized steel about 8 or 10 yrs ago. I can't remember the current %'s of the new vs. the old off hand but the new process allows the nitric acid and sulphuric acid that is in the coal ash and exhaust fumes to break down the zinc very quickly. Where as with 316L stainless the nitric acid will actually normalize the alloy and make it much more impervious to corrosion and hence why they offer lifetime warranies on the 316L with coal usage. They may aslo be passivating there 316L material like I did with my water coil which takes the normalization to the next level so to speak.

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Adamiscold
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Post Tue. Aug. 19, 2008 10:56 am

szembek wrote:What coaledsweat said. Use the regular black stovepipe for venting to the chimney. Any hardware store will have it available in 8" or 6" depending on your need. If you're unsure you could go to any shop that sells heating supplies or coal stoves and they will tell you the same thing.
Like I said, ventingpipe.com sells the regular black stove pipe but the manufacturing companies say it's for wood only. Is this still ok and would it pass an inspection if the guy asks for papers to see if it's rated for coal and he reads that it says for wood only?
304 is good, 316 is better
Again according to the manufactures there is only one made out of 304 stainless steel SuperPro and all the others Simpson, Metal-Fab, Metalbestos and Security Chimneys are made out of 430 stainless steel. Is 430 stainless steel better then 316 or would I be better off just going with the 304 instead? I don't see anything on 316 stainless steel.

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Post Tue. Aug. 19, 2008 11:48 am

To be honest, if you are this unsure, a website is definitely not the place to shop for this stuff. Go to a local heating supply shop. You will be able to speak to somebody in person who can answer your questions and show you the right stuff. Also those prices on that website seem insanely high, unless I'm missing something. You should be able to pick up 6 feet of black 8" stove pipe for under $20, I haven't checked lately, but no way is it more than $20.

edit: oh, I see your link was to double wall pipe. You don't need that for your interior stove pipe as long as you have proper clearance from combustible surfaces.

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Post Tue. Aug. 19, 2008 9:44 pm

Check this black stove pipe out from selkirk the maker of metalbestos. In think 316l is the most chemical resistant type of stainless availiable . 440 is good too but even more expensive than 316L and tend to microfracture with repeated heating and cooling however. I'll have to check on the 430 as I have never worked with that type. But 316L is what they use in all pharmaceutical plants and nuclear power plants.
http://www.heatfab.com/products/saf-t-pipe/index.asp


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