Copper firebox in a steel boiler

[clippermaniac]

I've been thinking about using a steel shell with a copper firebox and flues for a loco boiler with a 5.5" diameter. I know this was not an uncommon practice in full scale especially in English locos and traction engines. Seems like one would have conductivity where it is most needed and less conductive material in the shell. Anyone ever try this and how were the results.
Jim

 

[GWRdriver]

Jim,
I've rarely see this question raised or discussed in any live steam publication, nor do I know of an instance where it has been used in a model boiler, but that doesn't mean that it hasn't been raised or used. There would be two issues, first how to seal the joint (assumed to be at the mud ring) between the two materials, and then what if any problems might arise from electrolytic action between dissimilar metals. One can say, well copper flues are used in steel shells all the time without problems with electrolysis, which is certainly true. This suggest that electrolysis wouldn't be a problem with this construction either, but there's no evidence a dissimilar firebox has been tried in models to go on so we don't know. One can say this though, if it was an outstanding idea we would have seen and heard of plenty of instances where it's been used, but we don't.

 

[SignalFailure]

Jim,

Not uncommon in 'proper' engines as you say - my guess is that it's usual to see copper+copper in models because it's much easier to bash one from copper sheet than it is to make it in steel. Post whatever you find out about it, it'll be interesting to read!

Paul