stainless steel for a boiler?

[firebird]

But of course *beer* *beer* *beer*

 

[tel]

Only if you want your fuel to taste like boiled cabbage. For good tasting fuel you need a copper still.

 

[GWRdriver]

Here in TN we have a long and venerable history of making distilled umm . . . fuels, both above and below the radar, and centuries of experience has shown us that nothing works as well as copper.

 

[firebird]

Ah well, I'm sure I can find another source of fuel ;D ;D

Some way down the line, probably a long way, I might have a go at flash steam. The tube may serve as the outer casing for that?

Cheers

Rich

 

[tel]

Yep, it would be OK for that

 

[11thHour]

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.

From a recent article by Andy Probyn of Maxitrak - "As a fresh welders look at model boilers Marco started by saying why not use stainless steel? I related problems with cracking in this sort of boiler unless very careful water quality was maintained. “What about the new grades of stainless that avoid this problem” Marco asked. I had no reply to this one, except that it might be a step too far for our conservative boiler testers and insurance companies. It looks as though the usual pressures on manufacturers for modern efficiencies are not present in model engineering and anything that is not done the same way as it was a generation ago is not acceptable."

Not sure if this advances the arguement - just thought I would share.
Tim

 

[JorgensenSteam]

The risks involved in using unproven materials on a boiler are just too high.
I have operated a 12" diameter steel boiler at shows, and there are entire families standing around watching.

I don't mind loosing a flue or something, but there is no way I am going to risk a large boiler failure. Too much at stake.

 

[mrehmus]

Chloride stress corrosion can wipe the SS out in a heartbeat.

The first submarine I served on had an all SS nuclear power plant including the steam generators. Water quality control was uppermost and we used distilled water in the primary and secondary plants.

The seawater lines from outside were Aeroquip hoses which had a nasty habit of blowing apart. One did and flooded the engine room to above the deck plates. Seawater got into the vents on the condensers, the contaminated feed water was fed into the steam generators and in one quick second, cracked the tubes in the steam generators.

The cost to replace all the piping and the generators was so great, the Navy scrapped the submarine.

We ran a wee bit more than 30 psi but the SS will crack if it is hot and it will be.

Copper is a great traditional choice. Use the SS pipe as part of a low-temperature feed water system.

 

[ShedBoy]

I think the previous issue of Australian Model Engine using had a story about a different material to use for boilers. I can't remember what is was called but it had better corrosion resistance and was a stainless colour. I am at work so I can't check. Someone should have a copy nearby?

Brock

 

[ProdEng]

A boiler was made in New Zealand from SAF 2205 Duplex, which is apparently stainless.

Jan

 

[Jasonb]

From a recent article by Andy Probyn of Maxitrak - "As a fresh welders look at model boilers Marco started by saying why not use stainless steel?
Tim

Its interesting that Maxitrac and their associated boiler maker only offer boilers in copper and steel and "vestles" in stainless. None of there sites or adverts say they do copper boilers!!

J

 

[PMac]

Hi
here's a link to a guy that made a duplex stainless boiler for a Darjeeling Himalayan loco
http://sonadaworks.com/news/2011/10/28/steam.html

Thanks
Paul

 

[Steam4ian]

G'day all

Note that the Darjeeling boiler is 2205 Duplex not some unidentifyum. In Europe they seem to be making "stainless" steel boilers but using Grade 316L. I understand that 316L has a higher chloride resistance.

A problem with stianless steels is that they can change from anodic to cathodic over weld zones, also surfcae contamination can cause galvanic couple areas, all that you need for local intense corrosion. I have been associated (albeit indirectly so don't blame me) with a number of projects where stainless steel has failed.

A problem yet to be resolved with stainless steel is water treatment. Most times copper boilers have no treatment whereas steel has oxygen scavegers eg tannins for loco boilers, Hydrazine for power house boilers. Stainless steel loses its protective properties in an anoxic environement the very conditions needed for mild steel. The 316L may work in Europe where waters are traditionally hard, the line scale may protect the surface much as the hard water in Italy stopped the Romans from being poisoned by their lead pipes.

Regards
Ian

 

[Omnimill]

The subject of full size loco boilers came up the other day and it was commented that welded boilers don't seem to be lasting as long as the old riveted ones! I wouldn't know about that but if it is true I doubt there are many competent riveters out there to do the job now anyway... ;D

 

[Maryak]

The subject of full size loco boilers came up the other day and it was commented that welded boilers don't seem to be lasting as long as the old riveted ones! I wouldn't know about that but if it is true I doubt there are many competent riveters out there to do the job now anyway... ;D

A full sized scotch boiler with which I have had an intimate association and which is 65 years old of riveted construction has started to give problems with the rivets.

The mill where the steel was rolled for this boiler was not big enough to make the end plates and shell so they were made by welding sections together to get the length for the shell and the width, (diameter), for the ends. This took more than one attempt on the ends. The point is that since its assembly with rivets, the problems now arising are with the rivets and not the welds.

When you think of how many places there are with rivets where crevice corrosion can occur as opposed to correctly carried out welding then this does not come as a surprise.

I am curious, is the above anecdotal or is there some real evidence that the welds are failing. ???

Best Regards
Bob

 

[tel]

A properly riveted and caulked boiler will still allow a certain amount of flex, which is a good thing, but eventually the rivets will be the thing that goes. Shipbuilders found the same thing - a hull designed for riveting will break up pretty smartly if it is welded, same thing with certain old farm machinery (don't ask me how I know this)

 

[steamer]

It could be stress corrosion, was the boiler properly stress relieved after construction?

Dave

 

[Omnimill]

I am curious, is the above anecdotal or is there some real evidence that the welds are failing. ???

Best Regards
Bob

I don't know Bob. I think they may have been referring to the Tornado boiler that had to be returned to the manufacturers in Germany for repairs? In fairness no one said anything about welds failing.

 

[gabby]

Awwww come on Tel, How do you know this?