Re: Can you weld SS304 to zinc-plated ASTM A53 without corrosion?

Bill wrote:
> We have a product in constant contact with fresh water consisting of
> 304 thin-wall tubing (0.3 mm thickness) welded to a 304 reducer of
> about 3mm thickness. We are considering options to lower the
> manufacuring cost by changing the reducer material. Our manufacurer has
> suggested changing the reducer material to zinc-plated ASTM A53 carbon
> steel.
>
> 1. Is it possible to weld this to the SS304 tubing without resulting
> corrosion?
>
> 2. If not, is it possible to braze the SS304 tubing to zinc-plated
> ASTM A53 without resulting corrosion?
>
> 3. Any suggestions on any other material for the reducer to lower
> manufacturing costs in order to weld or braze the reducer to SS304
> tubing? The tubing is flexible, and must be made of SS304.
>
> Thanks for any help you can give.

Bill:

I agree with Mr. Andreas, but for another reason.

Either welding or brazing of zinc plated stainless steel is a very,
very bad idea. Once the zinc melts it quickly will cause liquid metal
embrittlement and grain (crystal) boundary cracking of the stainless
steel.

Tell the manufacturer who suggested a zinc plated steel to go look up
some of the discusions resulting from the 1974 Flixborough disaster.
(Perhaps he/she was not alive back then?) For example, see:
http://business.virgin.net/olwen.cox/pubs/FlixRevisit.htm

Also, for welding the stainless steel tube and reducer probably should
be 304L, or a stabilized grade.

Pittsburgh Pete
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