stainless steel for a boiler?

[firebird]

Hi

I have read some fors and againsts the use of stainless steel for boilers. This just came up on e bay and I couldn't resist having a bid. I won it for the princely sum of £4.70 a bargain.

Stainless steel tube 4-1/2in.o/d x 9-3/16in. long x 1/8in. thick

The question is can I use it to make a boiler? I'm thinking of using copper for the end plates silver soldered in. As with my other boiler I would be looking at a working pressure of around 30psi.

Any thoughts would be welcome.

Cheers

Rich

 

[Omnimill]

Until someone knowledgable in such things comes along ... I don't know anything about boilers or metallurgy but my guess would be using dissimilar metals is probably not a good idea? :-\

Update. I've just found this which indicates that Galvanic Corrosion should not be a problem for SS/Copper:

http://www.ssina.com/corrosion/galvanic.html

 

[GWRdriver]

Rich,
Methinks you have already made your decision. My concern would be one of setting precedent. Some unsuspecting individual might now mount the slippery slope and propose to build a 125psi coal fired boiler of stainless Unidentifyum and say to anyone who objected "Well this chap Rich did one and it's been OK." That being the case I'm unable to condone stainless for a boiler, but then what you do 'round back of the shed is your own business. Many in the ME community have an ongoing task of discouraging the Cheap = Good/Safe approach to boiler materials selection, for the good and safety of all. This doesn't help the cause.

 

[Florian]

Rich

Soldering for itself is not the Problem; Aswell to use different material for the end plates.

The problem is that when you heat crome steel up and it gets coloured, it is not protected anymore.
In fact what happens as long as there are tempering colors and water comes to those places there will be intergranular corrosion. And there's the dangerous thing about it: You won't see that unless you execute a structural examination.
And if you don't see it, the material failure will come suddenly and with no warning.

So, If you are going to use it for a boiler, you will have to pickle it with some aproppriate stuff for that job.
But then another problem shows up: This stuff etches off the solder and also copper and brass are attacked by it.

Finally, If you want to use it for a boiler, It would have to bee a Boiler completely made of chrome steel (or at least the part where you apply heat on the crome steal so you can pickle it)


I propose: use it for the smokebox or something similar.

Cheers Florian

 

[blighty]

i remember some guys talking about this at ally pally last weekend, it seems that SS boiler are ok, but the powers at be wont allow them.

http://www.nadmes.org.uk/pages/resources/boiler_testing.aspx


4. Testing of Steel Boilers

The testing of steel boilers is in many respects similar to that of copper boilers, however there are some differences as noted here:

Stainless steel boilers will not be accepted for test.
Steel boilers made of certified steel plate, welded by a coded welder and constructed to an approved design, shall be subjected to an initial hydraulic test of one and a half times working pressure, this will also apply to any subsequent test.
Steel boilers not conforming to all of these conditions will, on an initial hydraulic test be subjected to a a pressure of two and a half times working pressure. On any subsequent test, this required pressure will be twice normal working pressure.
A successful hydraulic and steam test will result in the issue of a certificate for the boiler concerned, which is valid from the date of the test for a period of one year.


i'm new at all this boiler stuff, so im learning as i go

 

[tel]

Any thoughts would be welcome.

Cider press
Olive press
Water tank
Door stop

... anything but a boiler, really!

 

[peatoluser]

A problem with stainless steel is that if you overheat it, chrome oxides will form, and the only way to remove them is with a file or grinder. fluxes wont do it.
also wereas copper conducts heat very well, stainless steel likes to hold it.
obviously, I dont know your level skill or brazing equipment, but it's something you should be aware of.

yours
peter

 

[Florian]

A problem with stainless steel is that if you overheat it, chrome oxides will form, and the only way to remove them is with a file or grinder.

Or it can be pickeled after the process that requires heat.

I also have been soldering chromesteel, its not a big deal when using silver solder. Even if it glows a little, the solder still flows if there is enough flux there (I use separate flux and bare rods of silver solder...) .

Cheers Florian

 

[firebird]

Hi

Thanks all for the swift response,

Thats pretty much what I thought so I'll use it for a water tank or similar, although the idea of a cider press sounds good Tel ;D ;D ;D

cheers

Rich

 

[Dan Rowe]

Rich,
I agree with the previous posters that stainless steel should not be used for boilers.

The AMBSC code now has a fourth section for duplex steel which is a very specialized type of stainless steel. It is allowed in the code but it requires some one experienced in the complex welding procedures required with it. That and it will take 30% more fuel as it has poor heat transfer ability.

http://www.smex.net.au/Store/Store_AALS-Codes.php

Dan

 

[Maryak]

Rich,

Sorry my friend but I agree with others who have said SS is a no no for boilers. A small still for moonshine does spring to mind

Best Regards
Bob

 

[Omnimill]

The idea of a cider press sounds good ;D ;D ;D

Pictures when it's done! :big:

 

[tel]

Pictures nothing! LARGE samples when it's done!

 

[steamer]

Pictures nothing! LARGE samples when it's done!

Large samples Sure! But I'm willing to let the sample sit a while! ;D

I seem to remember that stainless is prone to hydrogen embrittlment too.......

Dave

 

[Herbiev]

I'm with Bob on the moonshine setup. A coil of tubing inside the ss pipe, hook it up to an 18 gallon beer keg and you got a condenser for a small stil. I too would appreciate a sample :

 

[Omnimill]

Can be a bit dodgy: http://www.bbc.co.uk/news/uk-england-16742167

 

[Jasonb]

Personally I would not use it and there is also the fact you will never be able to run it in public if you wanted to.

Before totally dismissing stainless it should be remembered that in mainland Europe Stainless is very common and often the material of choice for model boilers.

J

 

[Entropy455]

Stainless steel retains significant strength at low temperatures. It is the material of choice for cryogenic liquid storage containers.

Stainless steel is specifically not permitted for use in boiler construction, because it has a tendency to form chromium carbides in the intergranular boundaries at elevated temperatures. This results in crack initiation points, which significantly weakens the material.

Commercial boilers are constructed out of ASTM-A515 Boiler Steel. This material is alloyed to retain strength at elevated temperatures. Prior to being placed into service (after forming and welding operations are complete), the entire boiler must be properly stress-relieved.

Although ASTM-A515 steel is the material of choice for constructing boilers, it is very brittle at lower temperatures - I.E. the material would be unacceptable for constructing a bridge, water-tower, or ship hull.

 

[firebird]

So how would one make a still ;D ;D ;D

Cheers

Rich

 

[GailInNM]

"So how would one make a still"

Rich,
I assume you want to make alcohol to fire a spirit fired boiler. ;D
Gail in NM