Stainless steel boiler/exchanger?

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rkcarguy
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Stainless steel boiler/exchanger?

Post by rkcarguy » Mon Oct 09, 2017 11:27 pm

Hey live steam group, I got a quick question for you. I have access to stainless pipe remnants through work, some rather large. Now I'm in my 40's and a diesel era guy, but is there any reason I couldn't use this for a live steam locomotive boiler instead of copper, brass, steel, etc, that I've seen used?
I'm pretty familiar with fabrication, I know that for firebox use it would warp like crazy and discolor, but for the water cooled portion of the boiler I don't see why it wouldn't work. I realize it has less heat conductivity than copper, but it would last a long time I think.

Harold_V
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Re: Stainless steel boiler/exchanger?

Post by Harold_V » Tue Oct 10, 2017 12:05 am

There's a considerable amount of information published in regards to failure of stainless when exposed to chlorides (water is commonly infused with chlorine). One article I read described the failure of heat exchangers in less than a year. For that reason, its use in boilers is often questioned. By sharp contrast, stainless boilers have been built and used successfully---so before making a decision about investing a huge amount of time in building a stainless boiler that may or may not serve as you'd hope, might pay to investigate until you've concluded that it is, or isn't, for you. Here's a link that may prove useful in that regard. http://www.ssina.com/corrosion/stress-c ... cking.html

H
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Marty_Knox
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Re: Stainless steel boiler/exchanger?

Post by Marty_Knox » Tue Oct 10, 2017 8:57 am

I worked as a Boilermaker for DuPont, in a primary acid plant.
DuPont had a whole Materials Science department, to select the exact material required. They never hesitated to spend the money for the material they decided was the best for the application - Carpenter 20, Hastelloy, Inconel, even Gold and Silver.

ALL our boilers were carbon steel.

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BigDumbDinosaur
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Re: Stainless steel boiler/exchanger?

Post by BigDumbDinosaur » Tue Oct 10, 2017 10:19 am

rkcarguy wrote:Hey live steam group, I got a quick question for you. I have access to stainless pipe remnants through work, some rather large. Now I'm in my 40's and a diesel era guy, but is there any reason I couldn't use this for a live steam locomotive boiler instead of copper, brass, steel, etc, that I've seen used?
I'm pretty familiar with fabrication, I know that for firebox use it would warp like crazy and discolor, but for the water cooled portion of the boiler I don't see why it wouldn't work. I realize it has less heat conductivity than copper, but it would last a long time I think.
I do not recommend the use of any austenitic stainless steel to fabricate any boiler in which tap water, treated or not, is to be used. The primary problem is reaction between chlorine that is present in tap water and the nickel that has been alloyed into austenitic stainless. Deterioration can be surprisingly rapid, as Harold has noted.

Also, welding of stainless steel gives rise to a phenomenon known as carbide precipitation in the fusion zone of the weld. What this is is the chromium in the steel reacting with the carbon that is also in the steel, producing chromium carbide. Carbide precipitation is unavoidable, even when using the low-carbon versions of stainless, e.g., 304L. Hence stainless welds do not have the corrosion resistance of the base metals and often fail when the base metals are still intact.

While it is tempting to fabricate a boiler from stainless because it seems to promise corrosion resistance, it isn't so. I recommend you stick with low carbon mild steel, as boilermakers have been doing for over 150 years.
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rkcarguy
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Re: Stainless steel boiler/exchanger?

Post by rkcarguy » Tue Oct 10, 2017 10:32 am

That's right, I forgot about the chlorine and crevice corrosion issues.
I could have tube sheets laser cut and put something together pretty quick. It's a tough one, because you think about the stainless tank water heaters with a lifetime tank warranty, those 50 year old stainless pans passed down from grandma, and you'd think it would work. I know in the pipe shop they purge the stuff(close off the section of pipe and fill it with shielding gas), and passivate the welds afterwards. It's really cool because it looks like it was welded from both sides but it wasn't.
I think I'd be more concerned with warping and/or differential heat causing cracks from expansion and contraction around the tube welds.

John Hasler
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Re: Stainless steel boiler/exchanger?

Post by John Hasler » Tue Oct 10, 2017 10:48 am

rkcarguy writes:
I could have tube sheets laser cut and put something together pretty quick. It's a tough one, because you think about the stainless tank water heaters with a lifetime tank warranty, those 50 year old stainless pans passed down from grandma, and you'd think it would work.

Perhaps the water heaters aren't welded. The pans aren't.

rkcarguy
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Re: Stainless steel boiler/exchanger?

Post by rkcarguy » Tue Oct 10, 2017 10:52 am

Properly cared for, I know cast iron boat manifolds last for decades in fresh water use so its makes sense. The only experience I've had is I got a free hot tub and wood stove from craigslist, and built a radiator looking thing from 304L pipe scraps which I then mounted inside the wood stove to heat the hot tub. I only used it for a couple years though before I sold the house.

rkcarguy
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Re: Stainless steel boiler/exchanger?

Post by rkcarguy » Tue Oct 10, 2017 10:53 am

John Hasler wrote:rkcarguy writes:
I could have tube sheets laser cut and put something together pretty quick. It's a tough one, because you think about the stainless tank water heaters with a lifetime tank warranty, those 50 year old stainless pans passed down from grandma, and you'd think it would work.

Perhaps the water heaters aren't welded. The pans aren't.
I bet you're right, I bet its stamped, and has room to grow.

squandt
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Re: Stainless steel boiler/exchanger?

Post by squandt » Wed Oct 11, 2017 7:40 pm

In the book" So you want to build a live steam locomotive" on page 102 you will find an artical writen by Douglas Alkire, (see IBLS web site under people if you want to find out about him).He built his engine in the early 1960's in 1'' scale. If this engine is still running it would give a good study in the use of s/s in boiler work.
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Trainman4602
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Re: Stainless steel boiler/exchanger?

Post by Trainman4602 » Wed Oct 11, 2017 8:06 pm

Doug's locomotive is still running. There are two other noted locomotive around with all stainless steel boilers. That would be Tom Millers Big Boy now in New Zealand and Dave Moor's Challenger. My K4 has stainless steel flues. There is nothing wrong with stainless steel in model boilers.

This subject has gone around on this forum many times.
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SteveR
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Re: Stainless steel boiler/exchanger?

Post by SteveR » Wed Oct 11, 2017 10:14 pm

From what I can tell, there are too many variables involved in boiler failure as well as too many different failure modes to definitively say that there is any one best or worst way to build a boiler. Its going to be a tradeoff between a bunch of factors, none of which anyone really keeps track of.

Maybe here is an (incomplete) list of factors that affect boiler failure:
boiler shell material type, thickness, welding rod type, welding style (mig, tig, stick, combinations), weldor skill, tube material, rolled in or soldered, solder type, tube thickness, water quality (dissolved solids, pH, water treatment), put away wet or dry, how often used (# of hours), number of heat cycles, maximum firebox temp seen during operation, operating pressure, what else?

What is a boiler failure?
Leak/pinholes at seams, leaks/pinholes in boiler shell, leaks at tube/shell interface, collapsed tubes, rusted tubes, rusted shell, failed seam, failed shell. What else?

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Carrdo
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Re: Stainless steel boiler/exchanger?

Post by Carrdo » Wed Oct 11, 2017 10:56 pm

The Australians and the New Zealanders are way ahead of us when it comes to research, testing and experience with the use of stainless steels in live steam locomotive boilers.

Just Google "Live Steam Boilers Duplex Stainless Steel" or just "Duplex Stainless Steel" and you can read the numerous articles written about this material and what has been done with it.

I am not trying to influence anyone one way or the other.

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