Listen, I have a question for anyone who can answer it. I’ve read that British steam locomotives, well some of them, had copper fireboxes. Anyone know the reason why?
Copper is more thermally conductive than steel. It certainly can’t rust, but I’m not sure if it’s still less susceptible to corrosion than steel. Those would be the good parts. On the downside, it costs more; and it’s not as strong. The latter might be negated by using thicker material, but see cost again. I think it would also be easier to form for an equal thickness.
Ed (one of anyone)
I did a Google search for locomotive copper firebox and below is one result. There are other results also.
Rich
Thanks for the answers, gentlemen! I know there was a British locomotive displayed at the B&O’s “Fair of the Iron Horse” in 1927, and that one had a copper firebox, to the amazement of the American railroaders. I was surprised to read of one built that “late” in the steam era still using copper instead of steel. Presumably there were others.
Speaking from experiance with model steam locomotives (11/2" scale). Copper firebox/boiler is the way to go. They are faster to get up to operating pressure, eaiser to control the fire in the firebox. And use much less coal than a steel firebox/boiler. I would think these same benefits would be found in the prototype too.
About forty years ago I was working with a boilermaker who had been in England with one of the U.S.Army Railway outfits during WWII. He mentioned that some British engines had copper fireboxes because of the better heat transfer and that they (the British) had a couple of men that went around to various shops just to do the welding on the copper fireboxes.
Interesting responses from everyone, and I thank you all. As far as corrosion resistance we have “living” proof of that on the Civil War battlefields here around Richmond, Va. On display are 12 pounder bronze “Napoleon” field guns, and aside from a green patina all are perfectly serviceable and capable of being fired at the age of 150. The Yorktown battlefield has bronze guns from the Revolution on exterior display and the same applies. Of course, bronze WAS a pretty expensive matierial to make cannon tubes from, but it was considered worth the expense just for the corrosion resistance, among other things.
Thank You.
Copper foreboxes were the norm in American Railroading for as long as most engines burned wood for fuel. With the changeover to coal it was noted that copper was no longer satisfactory. Wood soot and ash is soft but coal ash and cinders are very abrasive. Copper fireboxes just couldn’t stand up to a forced draft coal fire so steel came into use because of its superior resistance to abrasion.
Here’s a quick summary of the pro’s and cons of copper fireboxes compared to steel fireboxes.
Advantages:
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Copper is a superior conductor of heat (~6 greater than steel)
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Thicker plates give greater thread contact of staybolts
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Scale is less likely to develop due to greater expansion/contraction
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Copper is minimally affected by corrosive water
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Minimal corrosion or wastage
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Scrap value of copper is high
Disadvantages:
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Steel is much cheaper
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Steel plates are thinner, reducing weight
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The seams of the entire firebox can be welded, eliminating rivets and double thickness of plates (which retards heat transfer)
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No galvanic action between dissimilar metals
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Less expansion of steel reduces bending stress on staybolts
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Abrasive wear due to cinders is much higher with copper than steel
Hope that helps!
Danke shoen, Herr Rittmeister von Burgard!
Hi Firelock
About all said so far . Maybe a note to add : Lower heat transfer of steel caused problems when boilers originally designed for copper boxes were later equipped with steel boxes , still riveted at that time . Steel qualities were inadequate leading to frequent failures by ruptures firebox sheets, cracks usually starting from lower end at foundation ring . Why so ? As firebox sheets got heated by fire , metal could not expand freely because of restricting influence of staybolts and surrounding boiler sheets . In normal locomotive operation fire side of firebox sheets got roughly twice as hot as outer sheet to name a rule of thumb – clearly this meant tension to build up due to unequal thermal expansion . Fatal :
Thanks for the reponse, Juniatha. It amazes me that something we would think as a relatively simple piece of machinery such as a steam locomotive could have so many complicating factors. It just increases my respect for the designers and builders of the same who had nothing to go on but experience, mathematics and the metalugy of the time. No computer models or computer assisted design, just their own minds and guts. As a student of history a lesson I re-learn constantly is never underestimate the sophistication of the “old-timers”, they’ll surprise you every time!