Question 708Steam Plants - Assistant Engineer

The correct answer is C) 110°F. During normal operation of a main propulsion turbine, the lube oil supply temperature to the bearings should be maintained at approximately 110°F. This temperature range is recommended to ensure proper lubrication and cooling of the turbine bearings, which is crucial for the safe and efficient operation of the main propulsion system. Temperatures that are too low or too high can lead to bearing damage and premature wear. The other options are incorrect because 60°F is too low for proper lubrication, 72°F is too low for a turbine system, and 135°F is too high and could potentially damage the bearings.