True or False: The external self-closing stop valve must be checked for leakage at least once every six calendar months the cargo tank is in service.

The statement is indeed false because the NFPA 58 standard requires that the external self-closing stop valve be checked for leakage at least once every month when the cargo tank is in service. This frequent inspection is crucial to ensure safety and to prevent any dangerous leaks that could lead to harmful situations. In particular, these valves are critical in controlling the flow of liquefied petroleum gas and maintaining the integrity of the system. Regular checks every six months would not meet the safety standards set forth by NFPA 58, highlighting the importance of adherence to the recommended inspection schedule to safeguard against potential hazards associated with LP gas storage and transportation.