What is the purpose of a fusible plug in a boiler and how does it work?

The purpose of a fusible plug in a boiler is to provide a last-resort safety device to prevent catastrophic failure in the event of dangerously low water level. It works by melting at a predetermined temperature, allowing steam and water to escape and extinguish the fire, preventing overheating of the boiler's pressure-containing parts. A fusible plug is typically a threaded brass or bronze plug with a core made of a low-melting-point alloy, usually a lead-tin alloy. This plug is installed in....