AISI 321 corrosion

[siretb]

We have in one instance, tremendous corrosion with AISI 321 used in a gas burner shaft. The gas burner reheat flue gas.
Outlet (shaft outside) is around 250-300°C
Inside (high temperatures, resulting from flame)

The only factor is that when we have corrosion, the flue gas outside contains HCl (hydrogen chloride), about 1000mg/m3 and some SO2.
The flue gaz would contain about 10%O2, some 15% water, about 10% CO2 and some dust.

Question: would HCl/SO2 explain the difference in behavior, because experience is quite satisfactory on similar units where no HCl and no SO2 is present. NO is always present.

 

[TVP]

Answer: Yes.

 

[siretb]

Thank you, TVP. May I ask what a suitable material would be?

 

[EdStainless]

How mich corrosion are you seeing? Do you need something a little better, or a lot?

= = = = = = = = = = = = = = = = = = = =
Corrosion, every where, all the time.
Manage it or it will manage you.

http://www.trent-tube.com/contact/Tech_Assist.cfm

 

[siretb]

We need probably something that is a lot better. The shaft lasted for one month, before they were completly corroded
I am not a specialist in corrosion. From the photographs, entire sections of shaft was "eaten" (loss of material).
The velocity around the shaft is not that high (10-15 m/s) so I think that erosion is not significant.

 

[valfitman]

ALLOY C276 or Hasteloy C22 are exceptionally corrossion resistant to both wet and dry HCL. You might wish to check out their corrossion resistance to Sulphuric Acid and SO2.
Note these are very hard materials and can be difficult to machine if you are not experienced with them. They are also several times the price of austenitic stainless steels, but often a high price for the right material can work out lower cost in the long run