Final answer:
True, the external self-closing stop valve in the liquid discharge opening must be checked for leakage at least every six months to ensure the safety and environmental integrity of the ship's cargo tank operations.
Step-by-step explanation:
True or False: The external self-closing stop valve in the liquid discharge opening must be checked for leakage through the valve at least once every six calendar months the cargo tank is in service. This statement is True. It is part of the safety and maintenance protocols for vessels that carry liquid cargo. Regular inspections ensure that the containment system remains intact, preventing any potential environmental or safety hazards.
On container ships, maintaining the integrity of cargo tanks is crucial, especially when considering the transfer and management of ballast water (BW). Container ships often adjust their ballast to maintain stability, transferring BW internally among tanks or using open ocean water to comply with management regulations. These precautions, while important for stability and regulatory compliance, also highlight the necessity of having all tank components, including the external self-closing stop valve, in good working condition to prevent leakage or catastrophic failure.
Any leakage in the discharge system could lead to a spillover or unwanted discharge, which is not only a breach of environmental protocols but could also impact the vessel's stability. Regular inspection schedules are critical in managing these risks. Specifically, the semiannual check of the stop valve ensures that the mechanism that controls the flow of the liquid cargo out of the tank maintains its functionality and does not allow unintended leakage, thus upholding the integrity of the ship's operations and the surrounding environment.