Fire Box: Place where fuel is burnt.
Grate : The fuel is burnt on this.
Baffles: Plates are used for directing the flow of flue gasses.
Chimney: For ensuring that spent flue gasses exit the boiler at reasonable height. It helps in creation of natural draught.
Damper: Regulates amount of air through chimney.
Headers: Pipes which are connected to tubes and drums.
Tubes: For enabling the transfer of heat from the flue gasses to water.
Shell: The cylindrical vessel which has water to be converted to steam.
Mountings: For guaranteeing safe and satisfactory performance
Safety Valve: It releases steam if pressure inside boiler exceeds certain design limits. It can be of dead weight, spring loaded and lever types.