Hastelloy C276 versus Hastelloy C-22 4

[MedicineEng]

Dear "metal masters":
which arew the differenced between Hastelloy C-276 and Hastelloy C-22 and which of the alloy is more resistant to the contact with hot HCl solution at 9%?
Thanks for your help.

 

[weldtek]

I'm pretty sure Haynes Intl. offers technical and applications assistance. I think this number is still valid 800-354-0806

 

[CoryPad]

The difference is chemical composition, as shown in these documents:

http://www.haynesintl.com/mini/C276s/C276.htm

http://www.haynesintl.com/mini/C22s/C22.htm

Haynes shows the corrosion rate in boiling 10% HCl to be 288 mils per year for C-276 and 400 mils per year for C-22. Thus, C-276 has more resistance.

Regards,

Cory

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[MedicineEng]

Thanks guys.

 

[unclesyd]

Just for curiosity is this just plain HCl or is there any other components?

 

[MedicineEng]

Let me just explain the function:
This is a part in Hestelloy at the exit of our recovery boiler. As such, this is subject to a big chemical attack because the gases exit at around 350C from the boiler and are cooled down to around 70C trough water spray in this part. The main component that might attack this is HCl.

 

[metengr]

What is the composition of your flue gas and probably more important what type of fuel are you burning? Most of the scrubbers that are being installed on Fossil Plants use C-276 materials to handle the worst corrosion conditions which occur at the inlet flue gas duct to the FGD absorber vessel. I don't believe 10% HCl concentration is going to happen.

 

[Metalguy]

Elevated temp. and HCL is Hast. B territory.

 

[MedicineEng]

This is a recovery boiler that burns the secondary products of our production processes. Taht's why the HCl content.

 

[dutchmat]

Hastelloy C22 is a further development of Hastelloy C276 for better general corrosion resistance and to handle high concentrates of chlorides better at elevated temperatures.
But as often in practice it is not that easy and there are still area’s where C276 is better than C22, in certain reducing environments. In general C22 is to prefer in highly oxidising environments.

I also like to comment on Metalguy quote “Elevated temp. and HCL is Hast. B territory”

Be very careful!!! ONLY FOR REDUCING ENVIRONMENTS you can use a Hastelloy B type! A few ppm ferric or cupro oxidising salts will generate rapid attack, sometimes in days.

Regards
dutchmat