Because the pressure is held in small-diameter tubes rather than a large shell, watertube boilers reach high pressures and capacities and respond quickly to load. Industrial units use a steam drum on top and a mud drum below, joined by banks of tubes in D, A or O arrangements. In heating, compact copper-finned and flexible watertube boilers are common for hot water.
Plant's two big watertube boilers carry the process load, the little firetube is just for the office building.
On a watertube boiler, drum level control is everything: low level burns tubes, high level ships water down the steam line.
Also heard as
- water tube
- WT boiler
Related terms
Firetube boiler
A boiler in which hot combustion gases run through tubes that are surrounded by the water being heated.
Drum
A large cylindrical vessel in a watertube boiler where steam separates from water or where sediment collects.
Carryover
Boiler water and the solids dissolved in it leaving with the steam instead of staying in the boiler.
Bag
A local bulge in a boiler tube, furnace or shell plate where overheated metal has been pushed out by pressure.