What must be done if a steam boiler is operated in freezing conditions?

When operating a steam boiler in freezing conditions, it is crucial to ensure sufficient heating to prevent the freezing of water and components. This is because if water in the boiler or associated piping freezes, it can lead to serious damage, such as cracking or bursting of the pipes and boiler components. Maintaining a temperature that keeps water in a liquid state is vital for the safe and efficient operation of the boiler.

Proper heating prevents the formation of ice, which can obstruct water flow and create dangerous pressure buildups. Additionally, components such as pumps, valves, and gauges can be adversely affected by freezing temperatures, rendering them inoperative. By ensuring that the system is heated adequately, operators can protect the equipment and maintain its functionality.

Since the other options do not achieve the fundamental requirement of preventing freeze damage effectively, they are not viable alternatives. For example, allowing water to freeze would obviously lead to damage, using salt might introduce other problems including corrosion, and shutting down the boiler completely would not address the need to keep systems operating under low temperatures.