It is a 2 layered nozzle both layers made of incoloy 800H which refractory materials fills between them. temperature is around 900°C and CO, CO2, O2, H2O, H2, CH4 are passing inside the tube but the outer part of the tube experienced severe corrosion after 2 years.
images of the nozzle are attached.
which grades of high temperature alloys is more resistance than incoloy 800H and I can replace it in such a corrosive condition.
Hi Milad, incoloy 800H is not particularly corrosion resistant because it contains 40% iron. The nickel-base alloys without iron are significantly better, for example, Ni80Cr20, Nimonic 80A, Nimonic 81, Hastelloy C-263, Hastelloy C-22 and many others.
Dear vadim,
which one of these alloys are you sure that work better than incoloy 800H? i mean if you were me which one of them were chosen by you?
Dear Milad,
The choice depends on what you can find and in what form material to buy. The simplest variant is Nichrome (Ni80Cr20), which is available in the form of sheets and tubes on the world market. Also Hastelloy C-22 would be a perfect material, if you find it in suitable form. Nimonics as a sheet metal or pipe you hardly find.
Dear Vadim,
what do you think about inconel 718 or 617 or 625?
I also read that " Alloy C-22 should not be used in service temperatures above 1250° F due to the formation of detrimental phases which form above this temperature. " so it means maybe this is not a good choice.
Dear Milad,
In this case you should distinguish between two different types of corrosion: high-temperature corrosion and wet corrosion. Wet corrosion occurs at the start of combustion and when fuel is sulfur contaminated. It forms sulfuric acid, which attacks the material below 150°C. Against high-temperature corrosion Ni80Cr20 would be better than Hastelloy C-22, but it is the opposite not so good to wet corrosion (molybdenum-containing C-22 is much more resistant than Ni80Cr20 to acids like H2SO4).
Inconels are stronger and more expensive than Ni80Cr20, but less corrosion resistant to both types of corrosion.
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