Water-tube boilers are a type of boiler where water circulates in tubes heated by combustion gases. This design allows for high-pressure steam generation and efficient heat transfer. They are commonly used in power plants and industrial applications due to their ability to produce steam quickly and handle high pressures. In a water-tube boiler, the tubes are typically arranged in a way that maximizes surface area for heat exchange. The hot gases pass around the tubes, heating the water inside. This system is often preferred over fire-tube boilers for large-scale operations because of its efficiency and safety in high-pressure environments.