Boilers are one of the essential equipment onboard ships. Its purpose is to provide heating to the main diesel propulsion engine, to the bunker F.O. tanks (to make it less viscous for transfer purposes as well as easy ignition). The steam generated by the boiler can also be used for cleaning, and heating of the seawater in the freshwater generator thus evaporating it to make it potable water. There are two types of boiler mainly use in the Marine Industry, The water-tube boilers and the fire-tube boilers. The most common of which is the water-tube. In the water-tube type, water passes though lines of tube where it is heated by the use of a burner and a furnace.