A fire-tube is a type of boiler design where hot gases from a combustion process pass through tubes that are surrounded by water. This setup allows the heat from the gases to transfer to the water, producing steam. Fire-tube boilers are commonly used in various industries for heating and power generation due to their efficiency and relatively simple design. In a fire-tube boiler, the tubes are typically arranged in a horizontal configuration, allowing for effective heat exchange. These boilers are often favored for their ease of maintenance and lower initial costs compared to other types, such as water-tube boilers. They are widely used in applications ranging from small heating systems to large industrial processes.