Sulphidation of 9 Chrome Metal ?

[Kam999]

Can sulphidation occur in 9 Chrome Metal. Does 9 Chrome metal has copper in it.
We are seeing some flakes like deposit on the furnace tubes. These flakes glow in bright off white color when the furnace is running. I believe it might a product of sulphidation. Our tubes are 9 chrome.

Thanks
Kam999

 

[0707]

Sulphidation can occur in 9 Chromo moly materials such as A335 P9. ASTM A335 P9 has no copper in its composition.

I don’t know what kind of combustible you are burning in your heater, but the white colour flakes deposition over the tubes might be related with the type of fuel you are burning. Vanadium, Sodium, and Sulphur and Nox ash, are the usual compounds driven from the burners, which can contaminate heaters tube surfaces.

luis marques

 

[Kam999]

Thanks for the reply.

We burn lean refinery gas in the our burner. It is pretty clean fuel equivalent to natural gas. Could this fuel cause van / Na / nox ash deposit.

 

[EdStainless]

You could look at an analysis of the trace elements in the fuel and in the deposits.
This alloy is more sulfidation resistant than lower alloy grades, but it will still happen.

= = = = = = = = = = = = = = = = = = = =
Plymouth Tube

 

[unclesyd]

Table 5. Corrosion rates for different steel grades in 100%H2S at atmospheric pressure and two different temperatures (5).
Steel grade Composition Corrosion rate
(%) (mm/year)
Cr Ni 400°C 500°C
5%Cr steel 5 - 6.1 25.4
9%Cr steel 9 - 5.1 17.8
403 13 - 3.3 10.2
431 17 - 2.3 5.1
446 26 - no attack 2.5
304 18 9 2.0 5.1
310S 25 20 1.5 2.5

This data come from the following book by the way of the Outokumpu website.

D Peckner, I M Bernstein
Handbook of Stainless Steels.
McGraw-Hill, 1977