Need help on a non corosive high temp material

[Triped]

I work on a military base and we have a device that trains students how to fight fires. We have 4 fireplaces that use flame rods to detect flame. Right now the material used corodes within 2 days and the fireplace drops until we clean the rod. We tried stainless steel last week and it failed miserably, now we are looking for a better material that comes in 3/16" rods and can handle high temps. resist corosion and has good conductivity.

The stainless was perfect for conductivity, we had a solid reading unlike we ever had before, but that dropped off when the stainless heated up.

This is a very hostile environment, outside air (cold in the winter, humid in the summer)is drawn in when the fires are off, then when the fireplaces are enabled it gets very hot in the room, and the rod could have flame on it for up to 5 minutes, it then can be instantly cooled with high pressure water from the fire hoses, and the process repeated 4-6 times a day maybe more.

Any help would be appreciated. Also the material must be relatively easy to work with, and not expensive. The lengths we are dealing with is 17.5", right now the company is considering tungsten.

Also, the flame rod and spark does not get water on it directly, it has a housing over it to protect it, however a lot of steam is created and when the fire is out. Also the fire is fueld by propane, if that makes any difference.

thank you.

 

[Carburize]

Take a look at this article it might give you some guidance as to where to go

http://www.industrialheating.com/CD...ures/BNP__Features__Item/0,2832,12105,00.html

Most furnace parts which go through similar thermal cycles to the one you describe are made of nickel base alloys but unfortunately they do not meet your low cost criterion.

 

[hacksaw]

forget tungsten

what kind of deposit are you having to remove?

 

[metengr]

With this type of cyclic service duty and exposure to radiant heat (propane can have a flame temperature of 3500 deg F), you need to use an alloy like Inconel 601 for flame detection. This is a nickel-base alloy that can withstand exposure to temperatures as high as 2000 deg F. The oxidation data I have seen indicates Inconel 601 can be exposed in air to 2000 deg F for 15 minutes followed by cooling for 5 minutes in air, with no appreciable weight loss from oxidation.

As far as cost comparison to SS, Edstainless might have better information.

 

[arunmrao]

If you are able to spend money on tungsten(which is not any where cheap),you might then consider the Ni based alloys which are easily available in rounds and are more suited for your kind of application. visit

http://www.nidi.org

for more technical information.

Edstainless must be having a busy weekend for he has let go 2 questions. Very unlikely of him!!