Use of monel rivets in gas turbine exhaust stream

By exhaust plume are you implying a unconfined exhaust 400-500 deg F?

Low sulfur fuel, etc.?

Yes, this is core flow from an APU so it could well be around 1100 deg F before it starts to mix with entrained compartment flow. Fuels used, run the gamut of normal fuels, Jet A, JP 4 etc.

Any help would be useful since we only have non-documented experience rather than documented lessons learned and unfortunately thats what the customer wants !!

The best information that I can provide is that this would be a questionable application. Monel alloy 400 (SAE AS7233 rivet material) begins to lose strength when temperatures exceed 800 F. I don't have any data on resistance to sulfidation at those kind of temperatures. I would review the available information on the Special Metals website and contact them for specific data. A link to the website is below:

The APUs I have worked with generally have exhaust temperatures ranging from a min of 900° F to 1400° F. With failure modes that can provide 1700° F. I believe I had to Inconel fasteners.

Be sure of your mixing temperatures.

Allied Signal ( I think they are Honeywell now) publishes an APU installation design handbook.

Boathouse, I was wondering if you found any information for monel rivets. I have a monel rivet failure in an exhaust ejector assembly.