Question 49Steam Plants - QMED

The correct answer is C) 120°F. During normal operation of a main propulsion turbine, the lube oil supply temperature to the bearings should be maintained at approximately 120°F. This temperature is within the recommended range specified by turbine manufacturers and industry standards to ensure proper lubrication and cooling of the turbine bearings. Temperatures below this range may result in insufficient lubrication, while temperatures above this range can lead to accelerated wear and damage to the bearings. The other options are incorrect because 60°F is too low for proper lubrication, 72°F is generally considered a comfortable room temperature rather than a turbine operating temperature, and 140°F is too high and could potentially cause damage to the turbine bearings.