When securing a seawater-cooled shell-and-tube heat exchanger for an extended period of time, what statement represents the recommended operating procedure?

Correct Answer: Option D — The seawater side of the heat exchanger should be drained by opening the drain valves, while insuring that the vent valves remain open while draining.

Opening both drain and vent valves ensures complete drainage of the seawater side. If vent valves remain closed, a vacuum may form, trapping corrosive seawater inside the cooler. Proper drainage prevents stagnant seawater from causing severe galvanic corrosion and pitting of the tube bundle during extended idle periods.