Question 18Motor Plants - QMED

The correct answer is B) fire-tubes and stay-tubes. In a fire-tube auxiliary boiler, the tube sheets are connected by the fire-tubes and stay-tubes. The fire-tubes allow the hot gases from the furnace to pass through the boiler, transferring heat to the water. The stay-tubes provide structural support, connecting the tube sheets and keeping the boiler's shape. The other options are incorrect because: A) girder stays are not used to connect the tube sheets in a fire-tube boiler, C) the external boiler plating does not directly connect the tube sheets, and D) separate crown sheets are not a feature of the tube sheet design in this type of boiler.