The work of creating steam is done in the boiler, which consists of a double-walled casing enclosing several hundred copper or steel tubes through which hot exhaust gases are funneled from the firebox. Around these tubes, freshly injected water (or feedwater) circulates and begins heating. The hot water then flows to the back part of the boiler, called the barrel, where it is turned to steam against the crown sheet (the top) of the firebox.
Quick facts
Multi-tube boiler
Safety record
Worst explosion
First use in England
Insulating the boiler