Material for high temperature service in SO2 gas

[bennymartz]

Hi:
I need some help to choice a better resistant material for a butterfly valve that is a bypass valve for recovery boiler ( gas side) in the sufuric acid production, these are the conditios:


Combustion gas with 12% SO2( 79% nitrogen ,9% oxigen) at 1120°C (From the suphur burn) , 31 f/s(average) , in a duck work , 34in of diameter.

The last material that we use was Haynes 556 , but had a catastrophic failure las february.

Now we use temporaly, SS 310S, but we want to choice hayness HR 160 or Supertherm( duraloy trademark) .

Can anybody help me to choice or suggest a better material?, Thanks.

 

[0707]

Austenitic stainless steel types 321H or 347H and nickel base Alloy 600/600H and Alloy 800/800H might work.

 

[EdStainless]

HR-160 is the most sulfidation resistant grade that I know of.
One thought would be to use a 310 valve and have every surface coated (weld overlay or HVOF) with Ni-Cr. Without looking it up I recall that 50/50 gives good resistance

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