Question 49 3AE02 - Third Assistant Engineer (Alt)

The Correct Answer is C **Explanation for C (Steam cylinder drain valve):** When securing (shutting down and preparing for maintenance or an extended idle period) a steam reciprocating pump, the primary goal is to prevent water accumulation (condensate) inside the steam cylinder. If condensate accumulates and the pump is restarted, it can cause "water hammer," leading to severe damage to the piston, cylinder walls, and valves. Therefore, the **steam cylinder drain valve** must be kept open *after* the steam supply has been secured and *while* the pump is cooling down. This ensures that any residual steam that condenses during the shutdown process can drain away completely. These valves are often left cracked open or fully open during securing until the system is completely cold. **Explanation why other options are incorrect:** * **A) Water cylinder drain valve:** While these might be opened briefly to confirm water system isolation or during deep maintenance, they should generally be closed once secured, especially if there is a risk of freezing or contamination, and they are not essential for preventing damage from internal steam condensation upon startup. * **B) Steam supply valve:** This valve **must** be closed when securing the pump to isolate the steam pressure source. Leaving it open would mean the pump is still live and potentially operating, or at minimum, leaking high-pressure steam into the cylinder. * **D) Steam exhaust valve:** This valve is typically closed or isolated after securing the pump (or the line it vents into is isolated). Leaving the exhaust fully open is unnecessary once the steam supply is cut off and can lead to atmospheric contamination or uncontrolled steam release if the supply valve leaks. The purpose of securing is isolation, which requires shutting off both the inlet (supply) and the outlet (exhaust).