[Gasification] Re: [Stoves] RE: Durability of Stainless Steel

[Thomas Reed]

Dear Crispin, Dean and All:

Good question and answers below. 

We are continually amazed that "tincanium" last forever in applications 
where chemical reactions can reach 900C.  I believe this is explained by 
Das's rule:

A metal container will reach a temperature ~ halfway between the outside 
and the inside. 

It is also explained by the fact that radiant heat loss from the outside 
surface is proportional to (surface temperature )^4. 

So use stainless when you must, but be glad that is is often not 
necessary.  Harder to cut, weld, braze and buy.

TOM REED     BEF

Crispin Pemberton-Pigott wrote:
> Dear Dean
>
> Of that group, the two with the highest temperature resistance are 309
> (which is a European knock-off of 3CR12) and 409.
>
> 3CR12 is a titanium-stabilized low chrome stainless with a maximum working
> temperature of 750 C.  Above that the chrome starts to precipitate and the
> oxidation sites on the iron are exposed as the chrome finds its like and
> forms little balls.  Rust is the result.  It is very abrasion resistant.
>
> 409 is used on catalytic converters and has a working temp of up to 745 or
> so.  The destruction process is about the same.
>
> The others are more susceptible to heat, though they resist other things
> like acids and alkalis better up to certain temperatures.
>
> None of them will last a long time at 975 so whatever you are doing, use 309
> or 409 and plan to replace the part (i.e. design it to be easy to do so).
>
> Regards
> Crispin
>
> ----- Original Message ----- 
> From: "Dean Still" <dstill at epud.net>
> To: "'Stoves-List'" <stoves at listserv.repp.org>; "'ethos'"
> <ethos at vrac.iastate.edu>
> Sent: Sunday, June 04, 2006 3:31 AM
> Subject: [Stoves] Durability of Stainless Steel
>
>
> Dear STOVERS,
>
> Does anyone have the practical experience to predict the lifespan of 309,
> 310, 304 and 430 Stainless Steel at 975C?
>
> Best,
>
> Dean
>
>
>
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