high temperature intermediate tube supports

[mickeymouse]

I was involved in a project that we supplied the intermediate tube supports for a convection section (this has been about 5 years back). The cast intermediate tube support was exposed to high flue gas temperatures with vanadium and sulphur in the flue gas stream. The normal design criteria per API-560 is to use a 50/50 chrome/nickel casting or 25/20 chrome/nickel casting with insulating castable as a shield. The question is this: On this "particular" project the end user tried something a little different: the end user specified a high temperature ceramic coating on a 25/20 chrome/nickel casting in lieu of the standard design practices (that I mentioned above) for reducing costs and a possible long term solution to the harsh environment on the intermediate tube supports. Has anyone had experience with using this, and has anyone seen published data on this solution?
MickeyMouse (Structural/Mechanical)