Vertical fire-tube boiler

A vertical fire-tube boiler or vertical multitubular boiler is a vertical boiler where the heating surface is composed of multiple small fire-tubes, arranged vertically.

These boilers were not common, owing to drawbacks with excessive wear in service. The more common form of vertical boiler, which was very similar in external appearance, instead used a single flue and water-filled cross-tubes. Another form used horizontal fire-tubes, even where this added complexity, such as the Cochran boiler.